@@YGELLYPIKER Good god yes sir... the one where i locked on and was only saved by falling off a fibreglass hopup when my legs let go... 5A non rcd'd BS3036 board, neutral switched by a DIYer sometime in the late triassic, I stupidly checked L-N and L-E ( not realizing N was actually live... and with the switch off, N-E test would've shown me 240rich chunky volts before i nearly darwinated)
2 in my life, once when I was a kid (i was into electronics from a young age) and the other a few years back when I didn't fully isolate and got a shock off a rogue boiler circuit. I now fully isolate and follow procedures more stringently.
So few comments about the District Network Operators being responsible for the PEN fault debacle! If they were not trying to save money by dropping the 3rd cable, this never would have arisen, not to mention us spending ages cross bonding in years past.
As very old electrician (11th edition) I have always been unhappy about the safety of PME systems, as bonded metalwork can become live in the event of failure of the common earth and neutral conductor. As you say the neutral current will find any return path it can if neccessary via dangerous routes. Another aspect of this problem is that failure of the neutral on a 3phase distribution causes a loss of balance resulting in excess voltages on some phases and low on the remaing phases. I have experienced damaged expensive equipment as a result of this problem.
This has just answered a problem I had recently. A loose neutral on the main incomer of a 3phase DB was intermediately giving me 400 volts down to earth on L1 and 50 volts on L2 and L3. My initial thought was that it was a supply issue as opposed to inside the DB. Great to hear this from a proper tradesman. 👍
Long have I had a problem with TN-C-S supplies. They are dangerous by design and an idiotic cost-cutting measure put into place a long time ago. The problem now is what can be done about it? I see only two options: either re-design a huge chunk of the network or make it manditory for installers or DNOs to install PEN fault protection for each PME supply.
I’m retired now but 15 years ago I was looking after a London shopping centre and our PAT was put out and the contractor that won it was doing the test for 35p an item . I did tell the client that was not a proper test but all that they wanted was the test results at the end
Thats not really going to do much if you have bonded pipework. The current will follow the path of least resistance and will always prefur a nice juicy gas pipe to a measley little spike. Especially when you consider that pipework will also be bonded in your neighbour's houses providing a 100% metallic path back to ground.
When it comes to Grenfell we know it started in a Hotpoint fridge freezer. They use a flammable foam insulation and then promptly use 0.5mm flex with a 13A fused plug. Doesn't take a genius to conclude a fault in the fridge case the appliance flex to overheat due to the wrong-sized fuse in the plug for the flex and then ignite the foam insulation. My sister has a Hotpoint fridge, came with 0.5mm flex cable and a moulded plug with a 13A fuse fitted. I replaced the flex with something more appropriate aka 1.0mm and a 7A fuse for safety. Hotpoint technical support claims there is not problem with 0.5mm cable being protected by a 13A fuse!!!
To be fair, a 13A fuse will provide adequate protection against a hard short circuit (the extra energy deposited at the site of the fault is pretty immaterial, either way the item is probably a write off). That's why its generally recommended nowadays to use 3 amp fuses for low loads, and 13 amp elsewhere. For a lowish powered appliance like a fridge (150 watt or less?) I would thought that a 3 amp fuse would be more than enough, even allowing for inrush currents each time the compressor starts up. I'm old school and prefer to also protect against the long, slow overload type of fault so have swapped out my fuses for the most appropriate size like you did. I didn't swap the cables though, since that gives them an excuse to void any warranty.
@@tonywatson1412 oh yes there is, as well as 1A, 2A and 10A. I have a bunch of all of them. Not the sort of thing you can get easily but the likes of RS and Farnell will sell you them no problem. Or these days Ebay is your friend. Really if you don't know what you are talking about it us better to keep your mouth shut rather than embarrassing yourself in public with your ignorance.
@@tonywatson1412 I will add all my C13 leads have been fitted with 10A fuses as technically the C13/C14 combination is only rated for 10A so using g a 13A fuse in the plug is dodgy
We all know some companies are offering cheap ECR’s and some customers saying the inspection took less than an hour to perform . As for pen faults I have recently watched a John Ward demonstration of pen faults on a test rig he has made . It’s a Very informative presentation. Makes you wonder if all metal service properties should be only now TT or TN-S
It get's a bit more complicated in the US with split phase 240/120 volt with neutral at the center tap. Under ideal conditions, the neutral conducts no current. But in practice, some current does flow in the neutral which is the amount of imbalance between the two lines leads, So if there is 20 amps in Line 1 and 25 amps in line 2, the neutral will have 5 amps back to the transformer. In a single 120 volt circuit, the individual neutral has the same current as the hot line going back to the panel. It is a bit more complicated system, but much safer because standard receptacle and lighting circuits are only at 120 volts. For large wattage circuits like a dryer or electric range, 240 volts is supplied through the two lone leads, L1 and L2. Keep in mind this is still single phase. Rather than an RCD for the whole panel, we use GFCIs on individual circuits. And where as the standard RCD trips at 3o ma, the HFCI trips at 5 ma. In the main panel in the home, there is a neutral bus and a separate equipment ground bus. The equipment ground bus is connected to a ground rod. A piece of incoming pipe can not be used for the equipment ground. However, what can get a bit confusing is that the neutral bus is bonded to the steel panel and only at the main panel, any sub panels can not have the neutral bus bonded. This is because of the possible difference in ground potential between the main panel and the sub panel. A few volts difference in ground potential between the panel location is not uncommon, but wired this way, it has no effect. The sub panel is fed with 4 wires. Line 1, line 2, neutral and equipment ground from the main panel equipment ground bus. We use TN-C-S, modified as stated above. In most cases, each home has its own transformer. The neutral at the utility transformer is also grounded with a ground rod. It is a bit more complicated, but there is nothing common from one residence to another, other than transformer primary supply . Separate neutrals and separate grounds. In theory, we use a bit more copper in the home. 12 AWG (~4 square mm) for 20 amp 120 volt circuits and 14 AWG (~2.5 square mm) for 15 amp circuits. Generally, for the same household device/appliance, we use double the current than at 240 volts. And we run at 60Hz vs 50Hz, which makes a difference in motor speeds, otherwise for most residential applications the difference in frequency is more of the theoretical debate rather than a practical one.
@@professorg8383I didn't know it was common for each home to have its own transformer in the US. Isn't that rather expensive? And it means you have high voltage going all the way to each home, which must have safety implications.
@@thomasdalton1508 There is pretty wide variation in residential areas, But from a numbers perspective, the vast majority of homes exist in older, grid style urban neighborhoods. Power distribution in these areas is done by overhead distribution. Pole mounted transformers with short primary feeds and secondary feeds supplied overhead to the individual homes. Typical high voltage feeds are in the 7,000 to 10,000 volt range and are usually just a single phase, bare conductor across a given utility pole run. (very low cost) Many tens of millions of homes follow this basic old layout in city neighborhoods. pretty densely populated. These old city neighborhoods were built over time by individuals and not as large developments. It is not unusual to see homes that are 100 years different in age on the same streets. Most all these neighborhoods have been around a very long time. Many of them, predating electrical distribution! Rural is much the same in distribution but homes are much more spread out. In suburban areas that were built as developments across a short period of time, some differences can be seen. But in many. the overhead distribution is still dominant. In suburban areas, homes are spread out much more than urban neighborhoods, but not as widely dispersed as rural. Pole mounted transformers are pretty cheap in comparison to ground pad mounted transformers. Connections to a pole mounted transformer can be completely exposed and they are very easy to install. So if you look at total cost of installation, they are far more economical. In fact virtually none of these homes has high voltage coming to it. The high voltage and the transformers are out.on the utility pole runs along the public roads. However, in rural areas, you can find high voltage on poles that are on the private property, especially when the homes are a far distance from the road. Ultimately, these go to a pole near the home and have a pole mounted transformer on it for that home. The power company has an easement for their lines. I own a big chunk of land that has several smaller rural properties alongside it. I have 9 HV poles on my property which branch off the HV line on the county road. There are 5 separate additional services that come off that line, feeding mine and neighboring homes. (I have 3 services) Each service has its own transformer. None of the homes are visible from each other, That is fairly typical in rural areas where things are spread out. But even in densely populated urban areas, homes are far enough apart that shared transformers wouldn't be practical. It is really only in newer subdivisions that the overhead approach is not the norm and in those cases, property lots are pretty good sized, What you often see here is a pad mounted transformer for each property. But in these situations, transformers are usually near the road and fed with a buried HV line dropped from the overhead lines along the road. It then is common to have a couple hundred feet of buried low voltage lines to the house. In the end, it is far more costly to get rid of the overhead lines. The transformer may be at least 4 or 5 times the cost, plus the cost of the buried HV cable costing way more plus the installation to bury it. Then the cost to run the buried low voltage lines to the house is way more costly than overhead, So, we avoid HV lines on private property, (except in some spread out rural situations) And pole mounted transformers are far cheaper just for the transformer, let alone the installation costs. Shared transformers really only make sense in condo style homes and apartment complexes. I think that on the whole, European residential neighborhoods, are much more compact than in the US. We do still have some city neighborhoods where buildings are built right next to each other, sometimes even sharing walls. These are very old neighborhoods and there really aren't that many left. New York City is the most densely populated US metro area, but most of European cities are more than twice a densely populated. European population tends to be more evenly distributed. But the US has many vast areas of much lower population density.
Most of Europe doesn't have this problem because we must have a ground rod or multiple ground rods, the grounding system resistance must be in the single digit Ohms.
@@mernokimuvek Using common utility piping for earth grounding is a very ancient way to do this. Ground rods are cheap and easy. That has been the US standard for a very long time.
Got a shock from fairy lights back as a teen ager in the 1980s! Damn things must have been over ten years at the time and covered in more black pvc tape than was fit for purpose. Made me learn really quickly to be safe around cables and electricity.
Neutral wire monitoring on the individual service level is being trialled or already in action (via smart meters) in Australia. Unless the earth electrode has improbably low loop impedance total loss of the neutral will still result in lethal taps etc with a decent load being on in the premises. Foundation earthing may be a partial answer but not a complete one for a lot of countries given soil conditions. The issue here is largely aged overhead service mains, joints at the premises end deteriorating particularly in coastal services and 50+ years of the slight wire sway causing strands in the mains to break at the premises end. As far as I know the underground services, consumer mains join the network above ground in an enclosure on the footpath, do not have any significant problems because of no movement and being typically newer anyway. In my state, Queensland, there are approximately 200 notified shocks a year due to neutral issues out of a population of about 5.4 million people. Fatalities are rare. In my opinion, sooner or later any country that implements TN-C-S in some form will have to introduce monitoring.
This place has an MDPE water main and a galvanic isolator on the steel pipe to the gas meter so this neutral fault isn't an issue here, although it's on a looped supply. Or so I thought. I've just spotted that the isolator in the gas pipe was removed when the regulator was changed back in 2009 - you can see where it was as I couldn't paint the wall behind it.
All the EICR's in the world could not of prevented the awful Glenfell tragedy as the key problem was the cladding system. The fire started in a fridge ( not part of EICR) , but really it could of started by anything , in any flat and the effect could of been the same. That cladding type was banned by the USA years previous to the UK.
As a UK sparkie living in Ireland, they have the PEN conductor fix. All installs are TN-C-S like the UK but every install has its own earth rod, so its PME multiplied many times over...
Unless you have extremely low impedance on the earth rod, that doesn't solve the problem. It may reduce it, but it doesn't solve it. How much an earth rod will help with current flowing through gas mains depends on the relative impedances of the earth rod and the gas main - unless the earth rod has much lower impedance, there will still be a lot of current flowing through the gas main. If you don't have earthing through a gas or water main and are more concerned about all the exposed metal in your home becoming live, an earth rod will only reduce the voltage that everything is live at and possibly not by very much. A 230V supply with a load of 20A and an earth rod with a 200 ohm impedance (which is what people usually aim for), the earth rod will only reduce the voltage from 230V to 217V. To get down to a relatively safe 50V, you would need an impedance of about 3 ohms. You aren't going to get that by sticking a metal rod in the ground. In some countries, it is routine to bury a bare copper wire going all the way around the perimeter of the building, attached to multiple earthing rods. That's the kind of thing you need to do if you want your own earthing to protect you in the event of a PEN fault.
@@thomasdalton1508in Romania we have TNCS and every building has to have its own grounding and guess what? It has to be under 4 ohms. It is insane, i know a case when a property has been build without foundation earthing on a mix of sandy soil. They used about 20 x 1,5 meter surface zinc electrodes and only got 13 ohms, they had no more property to drive electrodes in the soil. On top of that, shit zinc/galvanized electrodes corode in 5 to 10 years, even quicker if they divert curent due to electrolisys. In the country side here, TNCS is an utopia, nobody has earth rods below 4 ohms because its extremly expensive for them and no rcd's. They have all the equipment grounding bonded to the line neutral without any type of earthing, no gasline , no waterline ,no rods. And when the PEN falls everything metallic goes live at 230V. Its a nightmare this shit TNCS, all done to reduce costs at the sake of human lives.
@@thomasdalton1508it’s fairly trivial for a gas meter installer to measure the current through the gas pipe before disconnecting it, of course. Easier than temporarily bonding across, even.
It will reduce the voltage abit But main thing is it will at least reduce the current down if you have a 30ma rcd 😊. Its not perfect by anymeans at 200ohms@thomasdalton1508
It's a function of time over conductor durability, I think. In pre-1980s properties a lot of the PEN conductors will have been made of durable grades of copper (i.e: Sized with long-term oxidation taken into account) but since then - And the continual expectation that as little money as possible be stretched across the widest area - PEN conductors will have gotten thinner, been made of suboptimal materials and/or replaced with poor substitutes (TN-C installs versus the much safer but slightly costlier TN-C-S). And it all comes down to that ancient and sacred art of „saving mon£y“... 💰⚡🔥😔
We have now had 2 neighbouring properties and our own on our early 1970s estate in Rutland have a PEN failure in last 10 yrs, all due to other utilities damaging the outer PVC sheath exposing aluminium PEN this then corrodes over time often many yrs due galvanic corrosion In our case 10 yrs after BG Dug pavement up for neighbours steel gas pipe corrosion and fail you could see the reinstatement still where it failed Cable is only few inches under tarmac In all 3 cases, the PEN Failed under load of electric shower So we have a ticking tome bomb of aluminium cable and steel gas pipes (one such caused a tragic explosion in Birstall few yrs ago )
In Serbia we use 3 phase at 25A (17kW residential) and no device in home draws more than 16A. Stoves are 3 phase by default. Every circuit is balanced by roughly equal load on other phases. So we have 3 light circuits, in bathroom 1 phase is boiler, second is washing machine and 3rd electric heater. By design, Neutral has always significantly smaller current than 3 phases (in theory should be zero, btw my home never had it over 8A of Neutral current when literally everything else but one device was off). PEN is used in modern installation, old system was more similar to Norway. My home has combination of old and new system, where Neutral is grounded at the substation, and I have local grounding strip. There is a thin bridge of 1mm thick wire that bonds neutral and ground at the meter, but will blow if there is any fault at power distribution system. As the fuses are just 25A at the meter, it is impossible to have more than 25A of fault current, and 1mm wire will blow in order of 100s of Amp, which can be only the fault in distribution system.
@@TheChipmunk2008 I actually did it myself. I am electrical engineer, and here regulation enforcement is very loose. Redone whole main electrical distribution around meter. Before my work, there was just a 100A switch before the meter and there were 3 fuses rated at 50A after the meter. Interestingly, to the electric central heating went 5G6 cable that was fused AT THE CABLE WE END, not at the meter (it had tap off before main fuse after meter). If there was any damage to that cable (like screw or rodent) only the fuse protecting it was at the substation. That is why I have redone the whole thing. As for grounding, the top floor was PEN, lower had separated Neutral and Ground with grounding strip (house was upgraded over the years) That is why I decided to connect all ground to the local ground strip, and then make a small connection between ground and neutral just in case.
I also made an RCD fault defeat for internaly RCD protected EVSE. I use 20A bridge rectifier, connect positive and negative, and I am left with 2 anty parallel diodes in series, and I put it inline with PE. Boats use this trick to avoid galvanic corrosion, by allowing voltage difference of up to 1.2V, but still passing fault current. Then, on EVSE side I connect neutral and 'pe' with 40ohm resistor. With leakage currents up to 30mA, diode has voltage drop of 1.2V and external RCD is not tripped. But internal RCD inside EVSE would trip and not cause a blackout inside the house. And if there is big fault current, Diode by default fails short.
That is interesting@@Mladjasmilic, as you probably know from following Efixx, our main fuses are before the meter and not (officially) allowed to be touched by anyone but the power company.
I use stamps on ALL my tools and one's where you can hit it to put a mark in, I use a blow torch and melt it in the plastic. I also engrave my tools as well.
Went to look at a chalet, on a chalet park, that they said had 'some electrical problem'. Got hold of the doorknob and got a strong shock off that! Another job call to a house, just newly connected to mains. where the customer complained of shocks from the kitchen sink and taps, found that the electrical supply co. had connected live and neutral but not the main earth!
If you get a shock off of any front door component that wouldn't normally be connected to an electricity supply (If there's only a traditional doorbell, a smartlock is not very likely) - Especially in a property that gets very few visitors - This might indicate a drugs factory. Call the Police. 👍
Not surprised by the fact that £30000 worth of copper cables gone missing at the college in Dundalk pretty sure it melted down by the time the Irish and English police finds it location
It’s interesting that the PEN conductor is considered to be that vulnerable. The biggest net owner in Sweden has decided to go back to TNC instead of TNS, even though half of my course to be a fully qualified electrician addressed the problems with TNC conductors.
Probably alot of old cables and the use of 1phase supply that causes the problem. I mean, when they start making a device that breaks the PE in a EV installation in case you get a PEN fault, something is really wrong.. You should never break the PE, unless you live in the UK apparently 😅
TNC in the network but split within the installation to become TN-C-S (pretty common arrangement around the world)? That's really what the UK is doing just that they split the PEN outside of their installation on the supplier side. I'd be surprised if it was TNC all the way through.
the goeverment need to launch another Grant for changing the Gas Pipes and water pipes from metal to Plastic for the water pipe and for the gas they should produce a type of pipe metal copper with hard plastic covered on top an also the fuse boards should. be returned back to plastic one’s also no more metal conduit and all electrical metal materials they have to return to plastic i doesn’t mater fire rating or no if the property start burning out then even if you have metal parts still will be burned but you still need to change them because they will return to black completely is not to much difference here better to save life's by returning them all to plastic than rather asking HSE to take action no one cares for your life
Don't underestimate how bad shocks from capacitors can be... designs with a poorly spec'd, or flat out missing bleed resistor are all too prevalent and they can store a few joules of energy that can be dumped in microseconds. Worst of all would be the caps in a microwave as they are charged to a few 1000volts, and are quite large uF wise, so a serious amount of energy in a very short time. Those first aid defibrillators dotted around the place all have beefy (not all 'beefy' caps are physically big either) caps and its the energy stored in the caps (batteries power control circuits and power the caps via voltage multiplier circuits) which is, again, dumped in microseconds, and they can restart (or conversly stop) a human heart.....
Also, a capacitive shock can cause secondary injuries, ask any 80s TV engineer who got hit with the EHT and tore their hand open yanking their hand back out of the chassis....
1. They aren't bleed resistors. They are discharge resistors because they *discharge* the stored charge. 2. "Few 1000 volts." Do you mean a few kilovolts? We're supposed to be electricians, let's use the right terminology.
@@deang5622 bleed resistors was the term a few years ago... the second term might be language dependant This is kind of like them saying the ring main is a ring final'... nope, at introduction it was named 'a ring main'. A ring final circuit is a modern equivalent, and is valid, but ring main is still also valid. The one point where this has changed is earth vs cpc... (and i disagree with this change)... i think a NON earthed cpc should NOT be allowed to be g/y
Oh i've had plenty of zaps off a capacitor over the years - i'm more electronics than electrical so it's a hazard i'm often exposed to. The worst i've had was a particular big bulk cap charged to 400v DC, burnt 2 small holes in my thumb - hand smoking and a lovely smell of crispy human.
Boss pulled the wrong fuse for the wrong flat. Changed an entire ccu and got a shock from the very last wire! Never again trusted anyone else to prove dead! Learned the hard way.
As a non sparky can someone explain in laymans terms what an NCD is, sounds pretty concerning. Is an NCD when the eathing isnt sufficient enough and electric can potentially move through the water pipes but instead of going to Earth from the pipe straps it could instead go through the boiler then bridge across to the gass pipe?
in Romania we have TNCS and every building has to have its own earthing and guess what? It has to be under 4 ohms. It is insane, i know a case when a building has been build without foundation earthing on a mix of sandy soil. They used about 20 surface zinc electrodes of 1,5 meters and only got 13 ohms, they had no more property to drive electrodes in the soil. On top of that, zinc/galvanized electrodes corode in 5 to 10 years, even quicker if they divert curent due to electrolisys. In the country side here, TNCS is a dream, nobody has earth rods below 4 ohms because its extremly expensive for them and also no rcd's. They have all the equipment grounding bonded to the line neutral without any type of earthing, no gasline , no waterline ,no rods. And when the PEN falls everything metallic goes live at 230V. I experienced myself a missing PEN in the countryside when the bonding became live and i shocked myself when i wanted to wash my hands at the water heater. Its a nightmare TNCS, all done to reduce costs at the sake of human lives.
Will RCBOs on all circuit be fine for a TT earth system. Or does it need one main RCD and RCBOs? Also the earth rod. Does it need to be visual under an inspection lid?
hi joe in every installation in rep of ireland have an earth rod ran back to board even it is a tncs system is this not the same in the uk also all circuits are now covered by rcbo /rcd in installation
TNCS systems in the UK do not use an earth rod. The earthing and return path back to the source is provided by the neutral line of the incoming DNO supply.
okay i see that but why not put in an earth rod in the installation cost or is it something in the rules and if you are up grading from a tt system and old rod is still in good condition when testing why do you not use it as a back up thanks for getting back to me @@deang5622
@@deang5622 From what I've seen you do have a defacto electrode through plumbing bonds and earthed items such as water heaters but not guaranteed of course since given plastic pipes appearing. At least you are moving in the right direction with the recommendation of a dedicated electrode but it's still not mandatory.
SPOT ON ,WHEN I HAVE watched welders weld on subs to main line gas mains and 6inch diameter ,fitting ovens with 1 inch supplies , they did the welding over a bank holiday ,when the factory was empty of people .
France has things well worked out. Every house has a 500mA differential relay at the entry. And the earth conductors separarely earthed so not normally connected to the neutral. Any neutral-earth connection or break will trip the main differential device. Circuits within the house use two-pole MCBs after 30mA residual current devices.
Honestly, diverted neutral current is one reason I will tell anyone who listens that TN-C-S is NOT fit for purpose in older houses with shared metallic services. For anything but new build with NO metallic services other than electricity, TN-S or TT should be REQUIRED, the fact TN-C-S is now the default is because of utter lack of investment. Our system is actual TN-S, (the estate is late 1950s, and the network hasn't been messed with, our PEFC/PSC readings prove this, our substation is 50 yards that way *points* ) If the DNO ever declare 'tn-c-s' everywhere as some have, I'm TTing the lot... (and yes we can, I know where our services are and we have PE water and gas)
Trying to get my head around this. Why do you say TN-C-S OK on new build with all plastic services? Won't it just end up with all grounded metalwork in the house at 240V? And no RCD protection if you get a shock from that metalwork. Is it just relying on the fact that there's no good ground to get a shock to? It's interesting to see this is being considered an issue now. My house (20 years old with plastic services) is TN-C-S and I've never really liked the idea in the 20 years I've lived here, but I hadn't heard any professionals worrying about it until now.
@@AJB1 all at 240v relative to true earth, still totally ridiculous, but nobody gets electrocuted. TN-C-S tries to make the actual earth potential the bad guy
@@AJB1 If the new building has steel framing it has to be bonded to the earthing system. Slab foundations under wet areas, bathroom, laundry if present etc can give low enough impedance to be a hazard too so in many countries you'll find it is a requirement to bond the rebar too. Sure the plastic pipework is not conductive so eliminates that potential hazard but there's still plenty of other opportunities to get yourself across the earthing system and the physical ground in modern construction. The key thing is to maintain neutral integrity and with the apparent state of your electricity network causing faults in the network itself that just isn't happening. Monitoring with automatic disconnection of all wires may be the only practical way forward over there unless a bucket of money is emptied into fixing the network pre-emptively. It will be interesting to see how it's handled.
@@retrozmachine1189 thanks! Yes, that all makes sense. I was just wondering why @TheChipmunk2008 had said "For anything but new build with NO metallic services other than electricity, TN-S or TT should be REQUIRED", and wasn't sure why he didn't think it should be required for plastic services. Is that the shock risk being lower with grounded metal services, or the fire risk not being there as things won't carry on working but pushing current through the services? Or just that you'll notice the fault as everything will stop working?
Must admit, my jaw dropped to the floor when even thinking that (except in a metal case fault situation or where grounding is needed in a rectified low voltage DC bench power supply's negative terminal) that *any* of the mains phase wires would EVER been directly connected to earth - let alone to allow a lethal situation of NCDs (Neutral Current Diversions) to occur. Even in the older EEE textbooks, have never seen such a set-up in a diagram until the one you've shown here at the beginning of the video. Thought it was bad enough when they used in some mains power appliances (especially in home audio & TV appliances) to use some capacitors to act as an 'earth bridge' between phases in the appliance, where if the capacitor failed, it would 'fail-deadly' and cause electrocution of the user - but this is next level that most wouldn't even know and it would explain why certain power supply systems tend to act weird with ordinary appliances. The practice of direct Neutral-Earth connections should be banned, so that it deals with the root of the problem, not with just the consequences of such.
I'm wishing YT had put this vid in my feed as soon as it had been uploaded - Watching now (4 months later) and this is the very first time my attention has been drawn to the risk of NCD...And as a consumer in a property with a TN-C¹ supply, I would have thought we'd have been made aware of the risk and given *how to detect/what to do in the event of* advice. 🤔 (¹ - I _think_ that's what I have. CPC and N are bonded together at the DNO fuse I'm pretty sure of that, but though I have protective bonds on the water pipes and the (unused) gas main I can't positively say that I have any external earthing. My water supply is through plastic piping, so that wouldn't count.) As a consumer with no current (sorry! 🙃) electrical qualification and nothing beyond a consumer-grade multimeter to hand, are there any ways we can *safely* detect and then test for an NCD incident? One thing that immediately comes to my mind is a friends house (Where flickering lights are a common happening) which is on gas, and if there is an NCD at his then it would be better found sooner rather than later! ⚠
Using the diagram shown at 0:58, place a CT clamp on the earth wire between the supplier cutout and MET. If more than a couple dozen milliamps detected, trip a double-pole breaker that isolates the entire incoming supply.
Charging an electrolytic capacitor up to a few hundred volts and throwing it casually to your cricket playing colleague suddenly seems like a bad thing... it took less than a week for us to train him not to catch things...
I think its important to highlight that electric shocks are far from equal. If you are not touching a neutral or anything earthed then you are less likely to get killed but if you are touching a neutral or anything earthed you get a far more dangerous shock that can easily be fatal and incapacitate a person so they cannot move away etc. Perhaps you could do a safety video on this so people do not get complacent after getting away with receiving an electric shock. Just a suggestion after i go a really bad shock recently that i have no doubt could kill but i got way with no harm.
@@edc1569 if it's a real issue then it needs addressing . I am sure a heavier external pen fault devise could be designed and installed such as they use with older EV chargers.
@@edc1569 I think you are worried over nothing there. Most of the rest of the world implements some form of electrode with TN-C-S systems. In Australia it is standard practice by regulations to have the rod sticking out of the ground (in a location where it is not a hazard and not likely to be damaged of course) with the earth wire clamped onto it also exposed to the elements and given a coat of zinc paint where the wire is clamped. Been this way since mid '70s. Also standard practice for electricians to check the performance of the earth stake to earth bar resistance as part of their work verification procedures, takes only a couple of minutes given they already have everything taken apart anyway.
But the electrode in Australia is so short and the wire is only 6mm² which is shocking to me. My house in Malaysia has a total of 9m long rods drilled into the soil (3× 3m rod) and the bare wire is 25mm² with pvc pipe for mechanical protection, pretty much standard here except for poor families.
@@IAmThe_RA The minimum domestic installation rod here is 12mm dia copper clad steel driven no less than 1.2m into the ground. There'd be a story behind your installation requiring an arrangement that comprehensive.
The first action re open PEN faults is to ban combined neutral earths in new networks, using separate earth or TT systems instead. Multiple current paths are inevitable with CNE's & metal service pipes as John Ward (JW) so excellently demonstrated on his TH-cam video last week.
Sorry but I’m getting sick to death of hearing people saying the grenvell fire was caused or could have been caused by shoddy electrical work. The fact is it was caused by someone newspapers on top of a fridgfreezer that fell behind the fridge freezer and blocked the compressor which then overheated and caused the papers to burn and ignite. The owner of the flat were it started confirmed that to journalists at the seen . People should learn to get their facts straight.
Apropos theft of tools, I have stated elsewhere that if manufacturers were forced to serialize their high value products, in an indelible way, this would surely help?
Correction: Lord Rooker graduated with an undergraduate degree in engineering, the minimum recognised qualification to gain the title as “engineer” or “electrical engineer” is a bachelors degree (bEng) absolutely minimum. Therefore he is not an engineer and his qualifications are irrelevant in this case, his history in manufacturing engineering in fact would mean if he was an electrician, he’d have more of a foundation to talk about these systems.
My understanding is that engineer is not a protected title in the UK the way architect, solicitor, barrister or accountant is, so you don't even have to any qualification to call yourself an engineer
An undergraduate degree is a bachelors degree. You’re an undergraduate when studying for for it. It’s an undergraduate course. When you’ve completed it successfully you are awarded a bachelor of whatever. It distinguishes from postgraduate which is what you are when studying for a higher degree than bachelor. He also has a postgraduate degree, in Industrial Relations.
@@raymolony I think that the only official Engineer title in the UK would be Chartered Engineer which is only awarded if you become a full member of one of the Engineering institutions. Even so, I'm not sure if it's a criminal offence to use it if you're not registered as such. I was a UK Chartered Electrical Engineer until I retired. If I had kept up my membership and expensive subscription after I would still be. I was also a Professional Engineer (P.Eng.) in Ontario. That is a protected title in Ontario and many other, if not all, Canadian Provinces. The USA also has the same system I think but I'm not sure if it's in all States. In Ontario it's usually the Professional Engineers Association, now called Professional Engineers Ontario (PEO) who police the misuse of the title and also any mistakes, incompetence or other issues with members as well as awarding the title of P.Eng. I had to surrender my P.Eng. title when I left the Canada. I did some professional design for jobs in other provinces whilst based in Ontario but because each province has its own system I used P.Eng. (Ontario) as a title. Never seemed to be a problem. The use of the word "Engineer" didn't seem to be a problem as long as there was no "Professional" in front of it. I've even seen things like "Carpet Engineer" on the side of vans. Microsoft got into a designation argument with the association about the use of "Engineer" at one point but I think they came to an agreement of some sort. PEO can remove someone's right to practice Professional Engineering (and lose the title) for various reasons. Someone who uses the title without it being granted by the PEO can be prosecuted and fined in the criminal justice system but it's usually flagged up by the PEO. All this means that even as an individual you need insurance if you want to keep your house, car, savings and pensions in case you make an engineering cock-up. If someone gets hurt you will probably go to jail. Even if you've retired and given up your professional designation you can still be held responsible. That's not why I left Canada, but which was for strictly personal reasons. When I then moved into this old house I thought about doing re-wiring myself. That meant getting a UK certification, which wouldn't have been an insurmountable problem. I looked at that but then decided that it was expensive for one job and the actual work was hard. It was easier for me to use a qualified electrician to get certification then all I had to do was provide cups of tea and biscuits as well as offer unwelcome advice.
![SAFEPLANET - ดาวเคราะห์ [ THE PLANET ]](http://i.ytimg.com/vi/4X1XL3I_k3c/mqdefault.jpg)
Time to fess up - how many electric shocks have you had?
th-cam.com/users/liveGzh5oVA3Q-s
You think you have had a shock until you have the real shock
No one use fingers to find a switch wire at a pendant anymore ?
@@YGELLYPIKERno because I’m not a retard
@@YGELLYPIKER Good god yes sir... the one where i locked on and was only saved by falling off a fibreglass hopup when my legs let go... 5A non rcd'd BS3036 board, neutral switched by a DIYer sometime in the late triassic, I stupidly checked L-N and L-E ( not realizing N was actually live... and with the switch off, N-E test would've shown me 240rich chunky volts before i nearly darwinated)
2 in my life, once when I was a kid (i was into electronics from a young age) and the other a few years back when I didn't fully isolate and got a shock off a rogue boiler circuit. I now fully isolate and follow procedures more stringently.
So few comments about the District Network Operators being responsible for the PEN fault debacle! If they were not trying to save money by dropping the 3rd cable, this never would have arisen, not to mention us spending ages cross bonding in years past.
As very old electrician (11th edition) I have always been unhappy about the safety of PME systems, as bonded metalwork can become live in the event of failure of the common earth and neutral conductor. As you say the neutral current will find any return path it can if neccessary via dangerous routes. Another aspect of this problem is that failure of the neutral on a 3phase distribution causes a loss of balance resulting in excess voltages on some phases and low on the remaing phases. I have experienced damaged expensive equipment as a result of this problem.
This has just answered a problem I had recently. A loose neutral on the main incomer of a 3phase DB was intermediately giving me 400 volts down to earth on L1 and 50 volts on L2 and L3. My initial thought was that it was a supply issue as opposed to inside the DB. Great to hear this from a proper tradesman. 👍
Long have I had a problem with TN-C-S supplies. They are dangerous by design and an idiotic cost-cutting measure put into place a long time ago. The problem now is what can be done about it? I see only two options: either re-design a huge chunk of the network or make it manditory for installers or DNOs to install PEN fault protection for each PME supply.
He’s 100% right on the shortcomings and HSE not doing anything.
I’m retired now but 15 years ago I was looking after a London shopping centre and our PAT was put out and the contractor that won it was doing the test for 35p an item . I did tell the client that was
not a proper test but all that they wanted was the test results at the end
Malicious compliance
We are paying the price for a cheaper method of supplying the network, no surprise there, and guess what, nothing will be done.
This will be why the regs now advise/ recommend you to add TT spikes to existing installations regardless of current earthing type.
Thats not really going to do much if you have bonded pipework. The current will follow the path of least resistance and will always prefur a nice juicy gas pipe to a measley little spike. Especially when you consider that pipework will also be bonded in your neighbour's houses providing a 100% metallic path back to ground.
Where does it say that
Imagine advising every existing installation they should have an earth spike installed just because
It’s recommended in bs7671 amd 2 for TNCS systems
@@mastergx1Are not most gas pipes now plastic?
@@roystevenson1375yes, they replaced mine about 10 years ago
When it comes to Grenfell we know it started in a Hotpoint fridge freezer. They use a flammable foam insulation and then promptly use 0.5mm flex with a 13A fused plug. Doesn't take a genius to conclude a fault in the fridge case the appliance flex to overheat due to the wrong-sized fuse in the plug for the flex and then ignite the foam insulation. My sister has a Hotpoint fridge, came with 0.5mm flex cable and a moulded plug with a 13A fuse fitted. I replaced the flex with something more appropriate aka 1.0mm and a 7A fuse for safety. Hotpoint technical support claims there is not problem with 0.5mm cable being protected by a 13A fuse!!!
To be fair, a 13A fuse will provide adequate protection against a hard short circuit (the extra energy deposited at the site of the fault is pretty immaterial, either way the item is probably a write off). That's why its generally recommended nowadays to use 3 amp fuses for low loads, and 13 amp elsewhere. For a lowish powered appliance like a fridge (150 watt or less?) I would thought that a 3 amp fuse would be more than enough, even allowing for inrush currents each time the compressor starts up.
I'm old school and prefer to also protect against the long, slow overload type of fault so have swapped out my fuses for the most appropriate size like you did. I didn't swap the cables though, since that gives them an excuse to void any warranty.
No such thing as a 7amp fuse available for UK plugs
@@tonywatson1412 oh yes there is, as well as 1A, 2A and 10A. I have a bunch of all of them. Not the sort of thing you can get easily but the likes of RS and Farnell will sell you them no problem. Or these days Ebay is your friend. Really if you don't know what you are talking about it us better to keep your mouth shut rather than embarrassing yourself in public with your ignorance.
@@tonywatson1412 I will add all my C13 leads have been fitted with 10A fuses as technically the C13/C14 combination is only rated for 10A so using g a 13A fuse in the plug is dodgy
@@jonathanbuzzard1376 Never use eBay/Amazon fuses. Junk, the lots of them!
We all know some companies are offering cheap ECR’s and some customers saying the inspection took less than an hour to perform .
As for pen faults I have recently watched a John Ward demonstration of pen faults on a test rig he has made . It’s a Very informative presentation. Makes you wonder if all metal service properties should be only now TT or TN-S
It get's a bit more complicated in the US with split phase 240/120 volt with neutral at the center tap. Under ideal conditions, the neutral conducts no current. But in practice, some current does flow in the neutral which is the amount of imbalance between the two lines leads, So if there is 20 amps in Line 1 and 25 amps in line 2, the neutral will have 5 amps back to the transformer. In a single 120 volt circuit, the individual neutral has the same current as the hot line going back to the panel. It is a bit more complicated system, but much safer because standard receptacle and lighting circuits are only at 120 volts. For large wattage circuits like a dryer or electric range, 240 volts is supplied through the two lone leads, L1 and L2. Keep in mind this is still single phase.
Rather than an RCD for the whole panel, we use GFCIs on individual circuits. And where as the standard RCD trips at 3o ma, the HFCI trips at 5 ma.
In the main panel in the home, there is a neutral bus and a separate equipment ground bus. The equipment ground bus is connected to a ground rod. A piece of incoming pipe can not be used for the equipment ground. However, what can get a bit confusing is that the neutral bus is bonded to the steel panel and only at the main panel, any sub panels can not have the neutral bus bonded. This is because of the possible difference in ground potential between the main panel and the sub panel. A few volts difference in ground potential between the panel location is not uncommon, but wired this way, it has no effect. The sub panel is fed with 4 wires. Line 1, line 2, neutral and equipment ground from the main panel equipment ground bus. We use TN-C-S, modified as stated above. In most cases, each home has its own transformer. The neutral at the utility transformer is also grounded with a ground rod.
It is a bit more complicated, but there is nothing common from one residence to another, other than transformer primary supply . Separate neutrals and separate grounds.
In theory, we use a bit more copper in the home. 12 AWG (~4 square mm) for 20 amp 120 volt circuits and 14 AWG (~2.5 square mm) for 15 amp circuits. Generally, for the same household device/appliance, we use double the current than at 240 volts. And we run at 60Hz vs 50Hz, which makes a difference in motor speeds, otherwise for most residential applications the difference in frequency is more of the theoretical debate rather than a practical one.
@@professorg8383I didn't know it was common for each home to have its own transformer in the US. Isn't that rather expensive? And it means you have high voltage going all the way to each home, which must have safety implications.
@@thomasdalton1508 There is pretty wide variation in residential areas, But from a numbers perspective, the vast majority of homes exist in older, grid style urban neighborhoods. Power distribution in these areas is done by overhead distribution. Pole mounted transformers with short primary feeds and secondary feeds supplied overhead to the individual homes.
Typical high voltage feeds are in the 7,000 to 10,000 volt range and are usually just a single phase, bare conductor across a given utility pole run. (very low cost) Many tens of millions of homes follow this basic old layout in city neighborhoods. pretty densely populated. These old city neighborhoods were built over time by individuals and not as large developments. It is not unusual to see homes that are 100 years different in age on the same streets. Most all these neighborhoods have been around a very long time. Many of them, predating electrical distribution!
Rural is much the same in distribution but homes are much more spread out.
In suburban areas that were built as developments across a short period of time, some differences can be seen. But in many. the overhead distribution is still dominant. In suburban areas, homes are spread out much more than urban neighborhoods, but not as widely dispersed as rural.
Pole mounted transformers are pretty cheap in comparison to ground pad mounted transformers. Connections to a pole mounted transformer can be completely exposed and they are very easy to install. So if you look at total cost of installation, they are far more economical.
In fact virtually none of these homes has high voltage coming to it. The high voltage and the transformers are out.on the utility pole runs along the public roads. However, in rural areas, you can find high voltage on poles that are on the private property, especially when the homes are a far distance from the road. Ultimately, these go to a pole near the home and have a pole mounted transformer on it for that home. The power company has an easement for their lines. I own a big chunk of land that has several smaller rural properties alongside it. I have 9 HV poles on my property which branch off the HV line on the county road. There are 5 separate additional services that come off that line, feeding mine and neighboring homes. (I have 3 services) Each service has its own transformer. None of the homes are visible from each other,
That is fairly typical in rural areas where things are spread out. But even in densely populated urban areas, homes are far enough apart that shared transformers wouldn't be practical.
It is really only in newer subdivisions that the overhead approach is not the norm and in those cases, property lots are pretty good sized, What you often see here is a pad mounted transformer for each property. But in these situations, transformers are usually near the road and fed with a buried HV line dropped from the overhead lines along the road. It then is common to have a couple hundred feet of buried low voltage lines to the house. In the end, it is far more costly to get rid of the overhead lines. The transformer may be at least 4 or 5 times the cost, plus the cost of the buried HV cable costing way more plus the installation to bury it. Then the cost to run the buried low voltage lines to the house is way more costly than overhead,
So, we avoid HV lines on private property, (except in some spread out rural situations) And pole mounted transformers are far cheaper just for the transformer, let alone the installation costs. Shared transformers really only make sense in condo style homes and apartment complexes.
I think that on the whole, European residential neighborhoods, are much more compact than in the US. We do still have some city neighborhoods where buildings are built right next to each other, sometimes even sharing walls. These are very old neighborhoods and there really aren't that many left. New York City is the most densely populated US metro area, but most of European cities are more than twice a densely populated. European population tends to be more evenly distributed. But the US has many vast areas of much lower population density.
Most of Europe doesn't have this problem because we must have a ground rod or multiple ground rods, the grounding system resistance must be in the single digit Ohms.
@@mernokimuvek Using common utility piping for earth grounding is a very ancient way to do this. Ground rods are cheap and easy. That has been the US standard for a very long time.
Got a shock from fairy lights back as a teen ager in the 1980s! Damn things must have been over ten years at the time and covered in more black pvc tape than was fit for purpose. Made me learn really quickly to be safe around cables and electricity.
Neutral wire monitoring on the individual service level is being trialled or already in action (via smart meters) in Australia. Unless the earth electrode has improbably low loop impedance total loss of the neutral will still result in lethal taps etc with a decent load being on in the premises. Foundation earthing may be a partial answer but not a complete one for a lot of countries given soil conditions.
The issue here is largely aged overhead service mains, joints at the premises end deteriorating particularly in coastal services and 50+ years of the slight wire sway causing strands in the mains to break at the premises end. As far as I know the underground services, consumer mains join the network above ground in an enclosure on the footpath, do not have any significant problems because of no movement and being typically newer anyway. In my state, Queensland, there are approximately 200 notified shocks a year due to neutral issues out of a population of about 5.4 million people. Fatalities are rare.
In my opinion, sooner or later any country that implements TN-C-S in some form will have to introduce monitoring.
This place has an MDPE water main and a galvanic isolator on the steel pipe to the gas meter so this neutral fault isn't an issue here, although it's on a looped supply.
Or so I thought. I've just spotted that the isolator in the gas pipe was removed when the regulator was changed back in 2009 - you can see where it was as I couldn't paint the wall behind it.
All the EICR's in the world could not of prevented the awful Glenfell tragedy as the key problem was the cladding system. The fire started in a fridge ( not part of EICR) , but really it could of started by anything , in any flat and the effect could of been the same.
That cladding type was banned by the USA years previous to the UK.
As a UK sparkie living in Ireland, they have the PEN conductor fix. All installs are TN-C-S like the UK but every install has its own earth rod, so its PME multiplied many times over...
Unless you have extremely low impedance on the earth rod, that doesn't solve the problem. It may reduce it, but it doesn't solve it. How much an earth rod will help with current flowing through gas mains depends on the relative impedances of the earth rod and the gas main - unless the earth rod has much lower impedance, there will still be a lot of current flowing through the gas main. If you don't have earthing through a gas or water main and are more concerned about all the exposed metal in your home becoming live, an earth rod will only reduce the voltage that everything is live at and possibly not by very much. A 230V supply with a load of 20A and an earth rod with a 200 ohm impedance (which is what people usually aim for), the earth rod will only reduce the voltage from 230V to 217V. To get down to a relatively safe 50V, you would need an impedance of about 3 ohms. You aren't going to get that by sticking a metal rod in the ground.
In some countries, it is routine to bury a bare copper wire going all the way around the perimeter of the building, attached to multiple earthing rods. That's the kind of thing you need to do if you want your own earthing to protect you in the event of a PEN fault.
@@thomasdalton1508in Romania we have TNCS and every building has to have its own grounding and guess what? It has to be under 4 ohms. It is insane, i know a case when a property has been build without foundation earthing on a mix of sandy soil. They used about 20 x 1,5 meter surface zinc electrodes and only got 13 ohms, they had no more property to drive electrodes in the soil. On top of that, shit zinc/galvanized electrodes corode in 5 to 10 years, even quicker if they divert curent due to electrolisys. In the country side here, TNCS is an utopia, nobody has earth rods below 4 ohms because its extremly expensive for them and no rcd's. They have all the equipment grounding bonded to the line neutral without any type of earthing, no gasline , no waterline ,no rods. And when the PEN falls everything metallic goes live at 230V. Its a nightmare this shit TNCS, all done to reduce costs at the sake of human lives.
@@thomasdalton1508it’s fairly trivial for a gas meter installer to measure the current through the gas pipe before disconnecting it, of course. Easier than temporarily bonding across, even.
@@JasperJanssen Of course, but it isn't only a problem when a gas meter is being removed.
It will reduce the voltage abit
But main thing is it will at least reduce the current down if you have a 30ma rcd 😊.
Its not perfect by anymeans at 200ohms@thomasdalton1508
I'm wondering why Neutral Current Diversion is, suddenly, a problem after the thick end of 150 years of electrical distribution?
It's a function of time over conductor durability, I think. In pre-1980s properties a lot of the PEN conductors will have been made of durable grades of copper (i.e: Sized with long-term oxidation taken into account) but since then - And the continual expectation that as little money as possible be stretched across the widest area - PEN conductors will have gotten thinner, been made of suboptimal materials and/or replaced with poor substitutes (TN-C installs versus the much safer but slightly costlier TN-C-S). And it all comes down to that ancient and sacred art of „saving mon£y“... 💰⚡🔥😔
We have now had 2 neighbouring properties and our own on our early 1970s estate in Rutland have a PEN failure in last 10 yrs, all due to other utilities damaging the outer PVC sheath exposing aluminium PEN this then corrodes over time often many yrs due galvanic corrosion In our case 10 yrs after BG Dug pavement up for neighbours steel gas pipe corrosion and fail you could see the reinstatement still where it failed Cable is only few inches under tarmac In all 3 cases, the PEN Failed under load of electric shower
So we have a ticking tome bomb of aluminium cable and steel gas pipes (one such caused a tragic explosion in Birstall few yrs ago )
EDF fitted Smart Meters here in February.
Gas meter removed - no voltage check across the pipes and NO jump leads clipped on.
In Serbia we use 3 phase at 25A (17kW residential) and no device in home draws more than 16A. Stoves are 3 phase by default.
Every circuit is balanced by roughly equal load on other phases.
So we have 3 light circuits, in bathroom 1 phase is boiler, second is washing machine and 3rd electric heater.
By design, Neutral has always significantly smaller current than 3 phases (in theory should be zero, btw my home never had it over 8A of Neutral current when literally everything else but one device was off). PEN is used in modern installation, old system was more similar to Norway.
My home has combination of old and new system, where Neutral is grounded at the substation, and I have local grounding strip. There is a thin bridge of 1mm thick wire that bonds neutral and ground at the meter, but will blow if there is any fault at power distribution system. As the fuses are just 25A at the meter, it is impossible to have more than 25A of fault current, and 1mm wire will blow in order of 100s of Amp, which can be only the fault in distribution system.
Thank you, I love to hear how other countries' systems work. Using 1mm wire as the link is interesting and clever
@@TheChipmunk2008 I actually did it myself. I am electrical engineer, and here regulation enforcement is very loose. Redone whole main electrical distribution around meter.
Before my work, there was just a 100A switch before the meter and there were 3 fuses rated at 50A after the meter. Interestingly, to the electric central heating went 5G6 cable that was fused AT THE CABLE WE END, not at the meter (it had tap off before main fuse after meter). If there was any damage to that cable (like screw or rodent) only the fuse protecting it was at the substation.
That is why I have redone the whole thing.
As for grounding, the top floor was PEN, lower had separated Neutral and Ground with grounding strip (house was upgraded over the years) That is why I decided to connect all ground to the local ground strip, and then make a small connection between ground and neutral just in case.
I also made an RCD fault defeat for internaly RCD protected EVSE.
I use 20A bridge rectifier, connect positive and negative, and I am left with 2 anty parallel diodes in series, and I put it inline with PE. Boats use this trick to avoid galvanic corrosion, by allowing voltage difference of up to 1.2V, but still passing fault current.
Then, on EVSE side I connect neutral and 'pe' with 40ohm resistor. With leakage currents up to 30mA, diode has voltage drop of 1.2V and external RCD is not tripped. But internal RCD inside EVSE would trip and not cause a blackout inside the house. And if there is big fault current, Diode by default fails short.
That is interesting@@Mladjasmilic, as you probably know from following Efixx, our main fuses are before the meter and not (officially) allowed to be touched by anyone but the power company.
@@Mladjasmilic Yes,. re: the galvanic isolator, well known to me on boats. I wouldn't have thought of this.!
I use stamps on ALL my tools and one's where you can hit it to put a mark in, I use a blow torch and melt it in the plastic. I also engrave my tools as well.
Went to look at a chalet, on a chalet park, that they said had 'some electrical problem'. Got hold of the doorknob and got a strong shock off that! Another job call to a house, just newly connected to mains. where the customer complained of shocks from the kitchen sink and taps, found that the electrical supply co. had connected live and neutral but not the main earth!
If you get a shock off of any front door component that wouldn't normally be connected to an electricity supply (If there's only a traditional doorbell, a smartlock is not very likely) - Especially in a property that gets very few visitors - This might indicate a drugs factory. Call the Police. 👍
Not surprised by the fact that £30000 worth of copper cables gone missing at the college in Dundalk pretty sure it melted down by the time the Irish and English police finds it location
The Gov should reverse the supply Reg's making the supplier provide an effective Earth to every supply.
It’s interesting that the PEN conductor is considered to be that vulnerable. The biggest net owner in Sweden has decided to go back to TNC instead of TNS, even though half of my course to be a fully qualified electrician addressed the problems with TNC conductors.
Probably alot of old cables and the use of 1phase supply that causes the problem. I mean, when they start making a device that breaks the PE in a EV installation in case you get a PEN fault, something is really wrong.. You should never break the PE, unless you live in the UK apparently 😅
TNC in the network but split within the installation to become TN-C-S (pretty common arrangement around the world)? That's really what the UK is doing just that they split the PEN outside of their installation on the supplier side. I'd be surprised if it was TNC all the way through.
the goeverment need to launch another Grant for changing the Gas Pipes and water pipes from metal to Plastic for the water pipe and for the gas they should produce a type of pipe metal copper with hard plastic covered on top
an also the fuse boards should. be returned back to plastic one’s also no more metal conduit and all electrical metal materials they have to return to plastic i doesn’t mater fire rating or no if the property start burning out then even if you have metal parts still will be burned but you still need to change them because they will return to black completely is not to much difference here better to save life's by returning them all to plastic than rather asking HSE to take action no one cares for your life
That Lewden CU in the background looks like it has antennas. Is that for the Bluetooth AFDDs to do a firmware update?
Don't underestimate how bad shocks from capacitors can be... designs with a poorly spec'd, or flat out missing bleed resistor are all too prevalent and they can store a few joules of energy that can be dumped in microseconds.
Worst of all would be the caps in a microwave as they are charged to a few 1000volts, and are quite large uF wise, so a serious amount of energy in a very short time.
Those first aid defibrillators dotted around the place all have beefy (not all 'beefy' caps are physically big either) caps and its the energy stored in the caps (batteries power control circuits and power the caps via voltage multiplier circuits) which is, again, dumped in microseconds, and they can restart (or conversly stop) a human heart.....
Also, a capacitive shock can cause secondary injuries, ask any 80s TV engineer who got hit with the EHT and tore their hand open yanking their hand back out of the chassis....
1. They aren't bleed resistors. They are discharge resistors because they *discharge* the stored charge.
2. "Few 1000 volts."
Do you mean a few kilovolts?
We're supposed to be electricians, let's use the right terminology.
@@deang5622 bleed resistors was the term a few years ago... the second term might be language dependant
This is kind of like them saying the ring main is a ring final'... nope, at introduction it was named 'a ring main'. A ring final circuit is a modern equivalent, and is valid, but ring main is still also valid. The one point where this has changed is earth vs cpc... (and i disagree with this change)... i think a NON earthed cpc should NOT be allowed to be g/y
Oh i've had plenty of zaps off a capacitor over the years - i'm more electronics than electrical so it's a hazard i'm often exposed to.
The worst i've had was a particular big bulk cap charged to 400v DC, burnt 2 small holes in my thumb - hand smoking and a lovely smell of crispy human.
@@blower1 bet you went off sausages for a few weeks (mine was an incident with a still glowing hot camping stove and being distracted)
So should we be installing jump leads across gas meters?
Recently a solar install near us in central England had £13,000 of cable stolen the night after it was burried.
Boss pulled the wrong fuse for the wrong flat. Changed an entire ccu and got a shock from the very last wire! Never again trusted anyone else to prove dead! Learned the hard way.
As a non sparky can someone explain in laymans terms what an NCD is, sounds pretty concerning.
Is an NCD when the eathing isnt sufficient enough and electric can potentially move through the water pipes but instead of going to Earth from the pipe straps it could instead go through the boiler then bridge across to the gass pipe?
It’s a money saving exercise…always has been ..TN-s is the common sense approach to installations
in Romania we have TNCS and every building has to have its own earthing and guess what? It has to be under 4 ohms. It is insane, i know a case when a building has been build without foundation earthing on a mix of sandy soil. They used about 20 surface zinc electrodes of 1,5 meters and only got 13 ohms, they had no more property to drive electrodes in the soil. On top of that, zinc/galvanized electrodes corode in 5 to 10 years, even quicker if they divert curent due to electrolisys. In the country side here, TNCS is a dream, nobody has earth rods below 4 ohms because its extremly expensive for them and also no rcd's. They have all the equipment grounding bonded to the line neutral without any type of earthing, no gasline , no waterline ,no rods. And when the PEN falls everything metallic goes live at 230V. I experienced myself a missing PEN in the countryside when the bonding became live and i shocked myself when i wanted to wash my hands at the water heater. Its a nightmare TNCS, all done to reduce costs at the sake of human lives.
Will RCBOs on all circuit be fine for a TT earth system. Or does it need one main RCD and RCBOs?
Also the earth rod. Does it need to be visual under an inspection lid?
Hse haven't responded to my concerns on health and safety breaches by the main contractor Vinci
Stonking and transgressive have to be the words. Another great weekly news vid as always.
Thankfully I don’t have Combine Earth and Neutral cable as Earthing is done totally on my property and is independent of Neutral.
hi joe in every installation in rep of ireland have an earth rod ran back to board even it is a tncs system is this not the same in the uk also all circuits are now covered by rcbo /rcd in installation
TNCS systems in the UK do not use an earth rod. The earthing and return path back to the source is provided by the neutral line of the incoming DNO supply.
okay i see that but why not put in an earth rod in the installation cost or is it something in the rules and if you are up grading from a tt system and old rod is still in good condition when testing why do you not use it as a back up thanks for getting back to me
@@deang5622
@@deang5622 From what I've seen you do have a defacto electrode through plumbing bonds and earthed items such as water heaters but not guaranteed of course since given plastic pipes appearing. At least you are moving in the right direction with the recommendation of a dedicated electrode but it's still not mandatory.
How can natural gas enclosed in a pipe explode without the presence of oxygen, no matter how much the gas meter may be heated up?
SPOT ON ,WHEN I HAVE watched welders weld on subs to main line gas mains and 6inch diameter ,fitting ovens with 1 inch supplies , they did the welding over a bank holiday ,when the factory was empty of people .
France has things well worked out. Every house has a 500mA differential relay at the entry. And the earth conductors separarely earthed so not normally connected to the neutral. Any neutral-earth connection or break will trip the main differential device. Circuits within the house use two-pole MCBs after 30mA residual current devices.
Great video. Complex topics explained well with good clear presentation and visuals.
Honestly, diverted neutral current is one reason I will tell anyone who listens that TN-C-S is NOT fit for purpose in older houses with shared metallic services. For anything but new build with NO metallic services other than electricity, TN-S or TT should be REQUIRED, the fact TN-C-S is now the default is because of utter lack of investment. Our system is actual TN-S, (the estate is late 1950s, and the network hasn't been messed with, our PEFC/PSC readings prove this, our substation is 50 yards that way *points* )
If the DNO ever declare 'tn-c-s' everywhere as some have, I'm TTing the lot... (and yes we can, I know where our services are and we have PE water and gas)
Trying to get my head around this. Why do you say TN-C-S OK on new build with all plastic services? Won't it just end up with all grounded metalwork in the house at 240V? And no RCD protection if you get a shock from that metalwork. Is it just relying on the fact that there's no good ground to get a shock to?
It's interesting to see this is being considered an issue now. My house (20 years old with plastic services) is TN-C-S and I've never really liked the idea in the 20 years I've lived here, but I hadn't heard any professionals worrying about it until now.
@@AJB1 all at 240v relative to true earth, still totally ridiculous, but nobody gets electrocuted. TN-C-S tries to make the actual earth potential the bad guy
WHICH IT IS NOT, TNCS is CRAP
@@AJB1 If the new building has steel framing it has to be bonded to the earthing system. Slab foundations under wet areas, bathroom, laundry if present etc can give low enough impedance to be a hazard too so in many countries you'll find it is a requirement to bond the rebar too. Sure the plastic pipework is not conductive so eliminates that potential hazard but there's still plenty of other opportunities to get yourself across the earthing system and the physical ground in modern construction.
The key thing is to maintain neutral integrity and with the apparent state of your electricity network causing faults in the network itself that just isn't happening. Monitoring with automatic disconnection of all wires may be the only practical way forward over there unless a bucket of money is emptied into fixing the network pre-emptively. It will be interesting to see how it's handled.
@@retrozmachine1189 thanks! Yes, that all makes sense. I was just wondering why @TheChipmunk2008 had said "For anything but new build with NO metallic services other than electricity, TN-S or TT should be REQUIRED", and wasn't sure why he didn't think it should be required for plastic services. Is that the shock risk being lower with grounded metal services, or the fire risk not being there as things won't carry on working but pushing current through the services? Or just that you'll notice the fault as everything will stop working?
Could they design an add on pen fault detection unit like used with EV chargers .
I can see that coming in future editions of BS7671 if the DNO's don't buck up their ideas
Must admit, my jaw dropped to the floor when even thinking that (except in a metal case fault situation or where grounding is needed in a rectified low voltage DC bench power supply's negative terminal) that *any* of the mains phase wires would EVER been directly connected to earth - let alone to allow a lethal situation of NCDs (Neutral Current Diversions) to occur. Even in the older EEE textbooks, have never seen such a set-up in a diagram until the one you've shown here at the beginning of the video. Thought it was bad enough when they used in some mains power appliances (especially in home audio & TV appliances) to use some capacitors to act as an 'earth bridge' between phases in the appliance, where if the capacitor failed, it would 'fail-deadly' and cause electrocution of the user - but this is next level that most wouldn't even know and it would explain why certain power supply systems tend to act weird with ordinary appliances. The practice of direct Neutral-Earth connections should be banned, so that it deals with the root of the problem, not with just the consequences of such.
Why aren't they bonding each side of the gas meter
I'm wishing YT had put this vid in my feed as soon as it had been uploaded - Watching now (4 months later) and this is the very first time my attention has been drawn to the risk of NCD...And as a consumer in a property with a TN-C¹ supply, I would have thought we'd have been made aware of the risk and given *how to detect/what to do in the event of* advice. 🤔
(¹ - I _think_ that's what I have. CPC and N are bonded together at the DNO fuse I'm pretty sure of that, but though I have protective bonds on the water pipes and the (unused) gas main I can't positively say that I have any external earthing. My water supply is through plastic piping, so that wouldn't count.)
As a consumer with no current (sorry! 🙃) electrical qualification and nothing beyond a consumer-grade multimeter to hand, are there any ways we can *safely* detect and then test for an NCD incident? One thing that immediately comes to my mind is a friends house (Where flickering lights are a common happening) which is on gas, and if there is an NCD at his then it would be better found sooner rather than later! ⚠
Camembert and Campari must be the snuck in words !
In my experience, the HSE has not been a significant authority for years!
Try a good blast of medium power RF .. make you jump
Electrical safety Is the job of the electrical safety regulators. Parliament is not interest. It’s not their job.
Using the diagram shown at 0:58, place a CT clamp on the earth wire between the supplier cutout and MET. If more than a couple dozen milliamps detected, trip a double-pole breaker that isolates the entire incoming supply.
Does anyone wanna buy any cable? It’s tree core…
haha!
I sometimes see 3 - 4 amps on my earth connection.
How would you check for that pen fault?
Search John ward pen fault. Very informative video
Will they be closing more schools due to this…
Was it "camembert" and "gooey"?
I've received electrical shock couple of times, feeling is wired
Charging an electrolytic capacitor up to a few hundred volts and throwing it casually to your cricket playing colleague suddenly seems like a bad thing... it took less than a week for us to train him not to catch things...
As many gas pipes are now plastic, earthing of gas meters becomes more and more pointless, as does water pipes.
Diversions & importance
I think its important to highlight that electric shocks are far from equal. If you are not touching a neutral or anything earthed then you are less likely to get killed but if you are touching a neutral or anything earthed you get a far more dangerous shock that can easily be fatal and incapacitate a person so they cannot move away etc. Perhaps you could do a safety video on this so people do not get complacent after getting away with receiving an electric shock. Just a suggestion after i go a really bad shock recently that i have no doubt could kill but i got way with no harm.
Campari? Camembert? What are these things?
Anaversery 😊 I like it!
it gets on my nerves People Calling Anaverserys Birth days!
Two words = Costa del (Watford)?
Campari and camembert? You have very eclectic tastes, my man!
9 weeks or is it 10....still waiting for my prize
Only 9 weeks. Come back when its 9 months
Errr Gas Pipes are Yellow Plastic now in the majority of places if pipes were all metal still there would be a far better earth system .
Would fitting an external earth rod negate this as a TT combined with tncs
Need maintenance, and if we start driving them in regularly we’re going to have a lot of incidents and bodged installs
@@edc1569 if it's a real issue then it needs addressing . I am sure a heavier external pen fault devise could be designed and installed such as they use with older EV chargers.
@@edc1569 I think you are worried over nothing there. Most of the rest of the world implements some form of electrode with TN-C-S systems. In Australia it is standard practice by regulations to have the rod sticking out of the ground (in a location where it is not a hazard and not likely to be damaged of course) with the earth wire clamped onto it also exposed to the elements and given a coat of zinc paint where the wire is clamped. Been this way since mid '70s. Also standard practice for electricians to check the performance of the earth stake to earth bar resistance as part of their work verification procedures, takes only a couple of minutes given they already have everything taken apart anyway.
But the electrode in Australia is so short and the wire is only 6mm² which is shocking to me. My house in Malaysia has a total of 9m long rods drilled into the soil (3× 3m rod) and the bare wire is 25mm² with pvc pipe for mechanical protection, pretty much standard here except for poor families.
@@IAmThe_RA The minimum domestic installation rod here is 12mm dia copper clad steel driven no less than 1.2m into the ground. There'd be a story behind your installation requiring an arrangement that comprehensive.
Had 35 shocks by thirteen,gave up counting..
The first action re open PEN faults is to ban combined neutral earths in new networks, using separate earth or TT systems instead.
Multiple current paths are inevitable with CNE's & metal service pipes as John Ward (JW) so excellently demonstrated on his TH-cam video last week.
camemebert ang gooey this weeks words
I'd say stonking and camembert have been snuck in
glad i still got lead sheaths cable seperate earth
Sorry but I’m getting sick to death of hearing people saying the grenvell fire was caused or could have been caused by shoddy electrical work. The fact is it was caused by someone newspapers on top of a fridgfreezer that fell behind the fridge freezer and blocked the compressor which then overheated and caused the papers to burn and ignite. The owner of the flat were it started confirmed that to journalists at the seen . People should learn to get their facts straight.
Camembert & Campari?
Food ones campari and camembert
Gooey, Camembert
Boy Scouts and alien - two words
Stonking and transgressive are the competition words
If the trade thinks it needs new laws! Then what it realy needs is proper electricians
Transgressive, Triumphed, camembert, flinging, gooey or bombshell 😂😂its got to be one these....
blackpudding and camembert
Camonbert gooey
Apropos theft of tools, I have stated elsewhere that if manufacturers were forced to serialize their high value products, in an indelible way, this would surely help?
Can we not have gas pipepes conected to a simple alarm if they reached a certain voltage? Seems quite easy.
I'm going with transgressive and Camembert for the words!
When are you testing the new green 221 wago and inline wago gelbox?
Stonking and transgressive!
Greet news weekly as always Joe 👍
Camembert and gooey
How safe Spider main in the house
Transgressive and gooey
Black pudding and Guey. I’ll keep guessing till I get my prizes Joe 😂
Shmuggled
Camembert
Camambert and mythological
Camembert & Bombshell
Campari Gooey
Transgressive and Scrolling
Camambert flinging
Correction: Lord Rooker graduated with an undergraduate degree in engineering, the minimum recognised qualification to gain the title as “engineer” or “electrical engineer” is a bachelors degree (bEng) absolutely minimum. Therefore he is not an engineer and his qualifications are irrelevant in this case, his history in manufacturing engineering in fact would mean if he was an electrician, he’d have more of a foundation to talk about these systems.
My understanding is that engineer is not a protected title in the UK the way architect, solicitor, barrister or accountant is, so you don't even have to any qualification to call yourself an engineer
An undergraduate degree is a bachelors degree. You’re an undergraduate when studying for for it. It’s an undergraduate course. When you’ve completed it successfully you are awarded a bachelor of whatever.
It distinguishes from postgraduate which is what you are when studying for a higher degree than bachelor.
He also has a postgraduate degree, in Industrial Relations.
@@raymolony
I think that the only official Engineer title in the UK would be Chartered Engineer which is only awarded if you become a full member of one of the Engineering institutions. Even so, I'm not sure if it's a criminal offence to use it if you're not registered as such. I was a UK Chartered Electrical Engineer until I retired. If I had kept up my membership and expensive subscription after I would still be.
I was also a Professional Engineer (P.Eng.) in Ontario. That is a protected title in Ontario and many other, if not all, Canadian Provinces. The USA also has the same system I think but I'm not sure if it's in all States.
In Ontario it's usually the Professional Engineers Association, now called Professional Engineers Ontario (PEO) who police the misuse of the title and also any mistakes, incompetence or other issues with members as well as awarding the title of P.Eng.
I had to surrender my P.Eng. title when I left the Canada.
I did some professional design for jobs in other provinces whilst based in Ontario but because each province has its own system I used P.Eng. (Ontario) as a title. Never seemed to be a problem.
The use of the word "Engineer" didn't seem to be a problem as long as there was no "Professional" in front of it. I've even seen things like "Carpet Engineer" on the side of vans.
Microsoft got into a designation argument with the association about the use of "Engineer" at one point but I think they came to an agreement of some sort.
PEO can remove someone's right to practice Professional Engineering (and lose the title) for various reasons. Someone who uses the title without it being granted by the PEO can be prosecuted and fined in the criminal justice system but it's usually flagged up by the PEO.
All this means that even as an individual you need insurance if you want to keep your house, car, savings and pensions in case you make an engineering cock-up. If someone gets hurt you will probably go to jail.
Even if you've retired and given up your professional designation you can still be held responsible. That's not why I left Canada, but which was for strictly personal reasons.
When I then moved into this old house I thought about doing re-wiring myself. That meant getting a UK certification, which wouldn't have been an insurmountable problem. I looked at that but then decided that it was expensive for one job and the actual work was hard. It was easier for me to use a qualified electrician to get certification then all I had to do was provide cups of tea and biscuits as well as offer unwelcome advice.