As an apprentice I appreciate videos like this, not only do you show the theory to it but then you show us a real world situation which is something I don't get in the classroom
You're a born trainer Cory, seriously. If you ever give up being on the job, take up a position to train others at a Tech or equivalent in the UK. Loved this! Oh, and Timmy _(Timmaaaa!)_ is eternally grateful 😂😂
brilliant, im currently on my level 2 training to be a spark and this helps me so much its one thing learning these things but its another to see it being done in real situations. your passion for the job really shines through aswell, i hope one day i will be as knowledgeable as you!
From watching your first video on artisan, following your music and watching oy channel. You’re are the master of all and learnt so much from you being an apprentice.
You say you're not a teacher Cory but you certainly have a talent for it. I'm not an electrician but find your videos fascinating. Unlike my old dad who, I swear, was immune to electricity the amount of times I saw him go: "oops, that one's live!" and walk away unscathed, I would not DIY but it's really handy to gain enough understanding to recognize a good electrician from a not so good. So thanks for the lessons, I am enlightened. 😄👍
An electrician that actually draws semi-decent circuit diagrams and actually sounds confident when writing equations up on the board; I am impressed. I truly am.
great video. whilst you were talking through the testing, i couldn't help but notice the labelling on the sockets - vacum and interwebs were my personal favourite 🤣
In Oregon US, two earth rods are required now. I got away without doing that when replacing the mains (consumer panel?) since I re-terminated the original wire. I am not licensed, but allowed to do the work as a homeowner if I do permits and inspections. Passed on replacing main panel.
And this right here is how you do a video for the Trades. Brings back both the pride and respect so often forgotten ✊👊 Very well executed, and much appreciated. And I'm confident in your success, no Doubt!!!!
Gerat video Cory, just finished my domestic installer course, and struggling to get my head round several concepts, you've made things a lot easier with these videos. And no-ones asked your peloton tag!
Great video!❤ We install alot of off grid systems Adding a genny gets intreasting.most victron inverters ypu can select eartth netrual relay as the bonding point. Confusingly cory... the battery regs say to keep the pme earth in island mode!😅 Lesson number 4: if an inverter/charger is powered by both a battery bank AND the grid (or a generator), this whole ground safety connection scenario is a lot more complicated, and is highly dependent of the specs of the components. Such as: • does the inverter have a neutral/ground connection inside? • does the generator have a neutral/ground connection inside? • are you installing the right ground connections without creating ground loops? But all of this would not change what happens for the ground connections for the AC output side of the system
Great Video Cory love your approach to teaching stuff. But I do find the 'Generator room' a bit of a laughing nightmare i.e. the Victron is mounted on combustable chipboard, below which are a stack of Battery Packs, all sitting next to an oil tank! and you're worry about getting an electric shock. I would either have the owner move the solar system to the otherside of the room, or build a fire wall between the solar system and the oil tank.
There are alot of fail safes and changes still to be made. This is more of a proof of concept phase at the minute, there are ALOT more batteries, and at least 2 more Inverters to come. Also, it’s in the remotest remote part of Dorset, and a good 70 metres from the house or nearest building, so at least if it goes pop, it’ll be a good distance from anything 🤣👍🏼
Working for a DNO we install these earth rods regularly, unfortunately if you cut one of those rods you will find they are copper coated steel rods😅 but love the way you explain the theory behind the earthing and bonding. Brilliant video.
Great video. Was wondering how “off grid” systems treat grid connections when there is a power outage. I’m in the thinking about it stage re and off grid/ ups style so will be interested in how you plan this out. If I decide to press the button then I’ll be giving you a shout.
My inverter has an island mode function which requires me to install a new cable between my house and garage so im going to install an earth nest whin i dig the trench then convert the house to TT hopefully get below 20 ohm
Great episode. As others point out, you’ve got a good teaching manner, not going to have students falling off the backs of their chairs because they’ve stopped following. Can you print a ‘vacuum’ sticker next time you are there? OCD etc.
If it's the same I've used @ 14:12 it's actually a copperplated steel rod. Had to do a temporary earthing and didn't get the rod all the way in so had to cut it off and noticed
not much classroom stuff really hits home with me straight away but your teachings do . bigup thanks and i look forward to the next vid . on a side note , what van did you get ? any good?
Hi Cory, many systems installed are in island/backup mode and as long as they are G99 compliant, do not require a separate earthing rod and can use the tncs earth. Here is the extract fyi : In island mode, an installation with EESS must comply with Regulation 21 of the ESQCR, and the PCE operates as a switched alternative to the grid. All live conductors, that is line(s) and neutral, that are to be powered in island mode must be disconnected from the grid. The installation may remain connected to the distributor’s means of earthing (where this is provided). Earthing arrangements for island mode operation In connected mode, an installation with a TN earthing arrangement (TN-C-S or TN-S) may use the distributor’s means of earthing. In a TT system, the consumer’s earth electrode is used - but care needs to be taken to ensure that this provides an earth of sufficient quality. However, when the installation moves to island mode, it is important to make special earthing provisions. Regulation 551.4.3.2.1 of BS 7671 states that, in TN systems, generators operating as a switched alternative to the public supply cannot continue to rely on the distributor’s means of earthing.
hi Bill, im curious on this one too. My system ( not installed yet) can go island mode everyday during a set period of time ( say 10:00 am - 15:00) . How can i have a separate earthing for only this period? ( does this mean i should not connect my battery / inverter to the main MET? or can i have 2 earth connections simultaneously ?
These setups are so strange to me being in Canada, the supply connection here doesn't bring in a ground at all just hot and neutral, we always have to install ground rods or a grounding plate on every job , and then bond that to the supply neutral only at the first means of disconnect (main breaker, main disconnect) and we're done that's the only arrangement....
Having the earth connected to the neutral of the incoming feed, or having a separate earth wire coming in on the incoming feed is a better strategy for earthing than using an earth rod. It is safer. Using am earth rod is the worst way to provide earthing. Firstly the earth rod gives much higher resistance/impedance than an earth wire, and secondly it is very much dependent on the moisture content of the soil, and that varies through out the year. So the Zs value is going to vary throughout the year through the seasons and hopefully it doesn't get too high.
In Belgium it's standard to have a TT-net, but the resistance should be less than 30 Ohms. (When taking the correct extra precautions, it can be between 30 and 100 Ohms.)
Ah that’s the video I wanted, I’m just doing the same thing for mine. What size earth cable did you use? I ran 25mm dam that’s a cable and a half In conduit. I want to see if I can go six rods deep just waiting for the adapter for my drill and hopping it can go that deep lol
you killed timmy! you b... loody did a good job of saving him! 😂😂 tbh, im not a sparkie but after this i now get the zs ze readings useage and the diff connection types (pme etc) bril cory! your a damn good teacher ! (and darn good sparkie too!)
Im no sparky, but watching other videos, it appeared to be that if the water pipe and gas pipework were bonded to the earthing, then there was a possibility of the system still being TNC-S by virtue of the fact you share supply lines with your neighbours whom quite likely are TNC-S. Is this negated when both the water and gas are supplied in alkathene (plastic) type pipework? Also, i thought the earthing rod had to be 10 metres away from all pipes or cables? All still seems to be a bit confusing. 🙂
I’m planning todo a off grid system. Solar & battery system. Biggest problem I have is I live in Finland and it’s practically winter half the year. How would I create enough power to be off grid fully?
Are there any kinetic energies around you? Wind, water streams, tide, sauna smoke? It would be a challenge, but with behavioural adaptation, and a lot of batteries, I think it would be possible. Maybe even via the route of electrolysis
Question : what if i am on a TNS system and Installing a Hybrid Inv / Solar + Battery. ( i will potentially use my supplier and go completely OFF-Grid only during the peak hours) .( in which case i will still need the existing earthing system) therefore, do i still need to install a separate earth Rod or connection to the MET is sufficient ?
Do you think there is a need for a 100mA Time delayed RCD before the CU as would be normal on a TT earthed system or is that protection not required here?
You're very intresting and precise in how you convey yourself! Im a Refrigeration engineer and want to become a Electrician! Your videos are so entertaining :D
Problamtic in my situation. I am mainly runnng offgrid but at times I need grid to charge and that activates the earth bond to the mains but grid disconnected there is no earth wire for AC out in the inverter and I can only ground the chassis to my own common earth bar which is connected to the copper vampire stake in the ground…. I hooked earth to an AC plug for now but if I go back to mains then that equipment has no Earth, hmmm.
On the other hand, with an off-grid system where the inverter is contained within the building, there is no potential between you and the generating equipment until you install the earth rod. So would an IT arrangement more practicable for off-grid generation?
'merican here .. I've got 3 ground/earth rods on my property from previous buildings, ... GOTTA have 'em here.... And, ... TBH... We NEVER "liked" little Timmy, .. BUT, .. Your calculations, way of explaining things/Edgumacating me, ... are TOP Notch, ... Well Done "Sir" , ... I salute you.......
Great question. In a usual situation it would be fine, and it’s rumoured the next regs update will encourage this ‘supplemented tnc-s’. But in an ‘off grid’ scenario, you must separate from the supply neutral and earth entirely.
A TT earth connected to an existing TNCS system is in effect just another earth point on the PME (TNCS being a PME arrangement). I think the reg's should encourage this - there are numerous advantages to having a local PME point (i.e. a TT earth) at a property - primarily it gives you another layer of protection if there is an earth fault on the DNO line....which can be a disaster with TNCS in scenario's where there is no other form of effective earthing via the utility bonding (plastic incoming water pipe, no mains gas at the property) Imagine a scenario where the incoming DNO earth is somehow broken, yet the live is still connected - with TNCS combined neutral earth, this will in effect make any externally conductive earthed appliances and your sinks, taps etc to be at mains potential! where there is no effective local earth to ground the floating potentials.
That's really interesting. Im looking at a hybrid system (without grid-tie) so imagine I'll need a local earth. I've got a load of 6mm wire for the panels' earth but is that thick enough for the external earth?
Hi Cory , when filling in your Zs for you circuits , would you add the R1+R2 to the 4.55 ohms and have worse case scenario or would you test Zs and obvs have a lower value. Some would argue Zs is irrelevant now with RCD protection.
Check T41.1 and 411.3.2.4. In the regs ( BS7671 ). The maximum Zs when using RCDs for fault protection in a TT system is based on 411.5.3 and Table 41.6 411.5.2 it does say that an appropriate overcurrent protective device may be used on a TT system for fault protection if the Zs value is permanently low.
Because in island mode the electrical system using the inverter is not connected to the grid. What you are always trying to do is provide a return path for the current to get back to the source from where it came. It has to do that, otherwise you don't have a circuit, and if you don't have a circuit then no current flows, and the breaker does not trip. If you are in island mode, that source is *not* the grid, so the grid earth wire does not help you in anyway whatsoever. Your earthing has to take the current back to the source from where it came. If there are batteries being charged by the solar panel and those batteries are providing power to the inverter, then the return path is back to the inverter (and ultimately back to the battery). If there are no batteries, solar panels only, then the fault current needs to return back to the inverter, and then it goes back to the solar panel. A circuit is required for current to flow. That's a closed loop from the source along the cables to the loads, back along the cables and back to that same source. The inverter acts as an AC voltage source.
Ok tha ks understand the physics there, but when not connected to the grid for supply you will still be connected to the provider earth? If, as in my instance, I can see my local transformer (30 yards away on a pole) and I know there is a provider earth below that, then am I adding anything by switching to a local TT other than probably increasing my earth resistance? Is there a worry about PEN faults with an off grind inverter? Can anyone explain the benefits / downside of just adding a local TT to your earthing without isolating from the provider earth? Feels like that would maintain lowest cost route back to source in all scenarios? Thanks
To answer your question. In addition to extraneous conductive parts being bonded to the main earth then the other two are: The requirements of ADS are met for the circuits All circuits within or passing through the location are protected by 30mA RCD (or RCBO/AFDD these days).
Awesome video, wish I had you as my teacher at college! When doing your ze test for the rod you mentioned you’re looking for a value below 100ohms. I always thought the TT highest value was 200ohms? Has something changed I’m not sure about?
Hiya. In an off grid system you wouldn’t have the return path to the transformer earth. The Victron inverter has a relay that bonds earth and neutral together thus providing your return path. Effectively you are creating a TN-S system. The relay opens when you connect to the grid.
It is not quite that. You might have a path to the earth of the transformer but it is not a return path for the current, as the current did not originate from that transformer. So whilst there may be a physical connection there, it doesn't provide a return path.
Hi Cory, Nice video 😊 What happens when next doors gas & water bonding is metal pipe work & linked to your properties TT supply & they are on a tncs supply ?
In this scenario I’d probably recommend a plastic pipe break be installed. This property had plastic incomers and it’s own partly off grid supplied so wasn’t an issue.
Cory Milwaukee Man Mac’s wipe board is out again shame you didn’t have a full set of colours. Maybe if you had the yellow one you could of been Timmy’s saving angel. 😂 Mockery is my only option because the Math went over my head 😊
Poor Timmy.I thought he had fallen down the well!! Now you telling us he is touching the frames of ungrounded electrical equipment. Where is Lassie when you need her?. Great tutorial Cory!! I always like your cardboard classroom. Groundrods are common here in the states with only one common path to ground at each site location. It felt like we came to the duscussion without a prelim. of why you are doing the change. When you say mains .do you mean electrical utility supplyer?. Your vlogs always require a second viewing. Seperate and apart from the two moons over Myhammi what kind of Van did you get?. Happy Easter,!!!!!
A potential upgrade might be an earthing mat - a big ol copper plate that gets buried. Understandably not as convenient but worth leaving as a note for the homeowner if they have earthworks planned. That rod is a good length!
Given that the impedance is down to less than 5 Ω in this case, no upgrade is worth it. The impedance is more than low enough to trip a breaker or RCD. But as an earthing solution where the resistance is coming out too high, yes, it is a good approach.
@@deang5622 I was thinking in terms of how many years of use rather than the immediate state electrically when it's still quite new. Degradation over time.
Everything is TT in France. Multiple rods and 10m long 0.5m deep buried bare copper chunky stranded cable is sometimes necessary to meet the test impedance, made by the Consuel (state quango) site visit inspection.
Great video Cory... I'm all Earthed Out now🤯 One thing though about Gas/Water bonding... you forgot about MDPE incomers 🤫 Oh, and by the way, that kewtech is anything but basic... recently helped my nephew get one which like you he loves and at a 'bag of sand plus the dreded' ain't cheap given his lack of income at the moment. Anyway great video and keep doing what your doing. Respect 👊
Hiya mate, I'm sure you were on another channel before this. Its great what you are teaching so I can learn it all from you ;) I'm a plumbing and heating engineer and just installed solar thermal. The customer has solar pv but they asked me about batteries. What batteries should they choose? I said there are a few TH-cam channels out there hut only a few like yours include the safety aspect and explain why we have to do it that way in England. So I want to share your channel with them. Do you have any recommendations please?
I see you haven't lost your angle drilling skills, Jordan must be proud. Another interesting learn with Cory. I've always thought sparks were the cleverest trades.
Great video mate love your content! One quick query though where does it state 100ohms or less for the zs of tt system as the maximum permitted zs for a tt is 200ohms?
The limit of 200 ohms is NOT the value of Zs. You are mixing up the total earth loop fault impedance with the impedance of the earth rod connection. The 200 ohm limit is on the impedance of the earth rod itself. Table 41.5 in the regs says the resistance should be as low as practical. There is no hard limit of 100 but obviously 100 is better than 150. And the key value is the Zs value for a 30mA RCD if the circuit is protected by RCD is 1667 ohms and that is Table 41.5 too.
Interesting work. Is there a requirement for measuring the earth rod resistance, and a minimum ohm value for it to be effective? Many farms are on TT network and I remember the gravel round the rod was not good at all.
Yes there is. IET says no more than 200 ohms. IET says this: Table 41.5 of BS 7671:2018+A1:2020 states that 1667 ohms is the maximum earth fault loop impedance value where an RCD with a rated residual operating current of 30 mA is used. However, it is important to take into account the ‘*’ referring to note 2, which states the resistance of the installation earth electrode should be as low as practicable and a value exceeding 200 ohms may not be stable. But what does not be stable actually mean? Note 2 of Table 41.5 refers to Regulation 542.2.4 of BS 7671:2018+A1:2020, which states ‘The type and embedded depth of an earth electrode shall be such that soil drying and freezing will not increase its resistance above the required value.’ The main factor affecting resistance to Earth of an earth rod is the depth of installation. It is appreciated that this information is difficult to obtain, but to mitigate the effects of the soil drying out, the earth electrode should be installed at a depth sufficient to reach the water table of the soil to remain effective. What effect does temperature have on soil resistivity? Temperature plays a big part in soil resistivity, when the ground freezes, the resistivity increases substantially. An earth electrode which is installed during moderate weather may become ineffective during winter. Table 1 indicates typical resistance values per metre for various temperatures for assumed conditions of 15.2% moisture content sandy loam. If the soil temperature varies from 20c to -5c, the resistivity increases 10 times, from 72 Ω/m to 790 Ω/m. This is why the note referring to 200 Ω may ‘not be stable’ is so important.
Not an electrician so genuine question… if we have RCD’s that trip if the line and neutral aren’t balanced, how come we actually need bonding anymore? If the current wasn’t all going elsewhere and not back down neutral then rcd would trip?
Cory, I was speaking to a fellow sparky the other day, and he said he went to change a socket front at a property which was off grid, with a solar battery array, and a back up generator to charge the batteries. He found there was no earth rod, and his tester wasn't picking any form of earth up. he spoke to the solar company as it is a recent install, and they said there is no requirement to provide a supply earth, which I found baffling, as surely that is extremely unsafe, and the RCD wouldn't operate?? Am I right?
Absolutely that is not true. There is a requirement to provide an earth, it sounds like a very dangerous install. If you would like me to take a closer look, email me some more info & pictures cory@oyelectrical.com
Not a sparkie and just curious, what protection in this case if someone digs up the concrete and cuts the new earth, would that kill Timmy ? and would it only get noticed on EICR?
No it wouldn't be because there is a 30mA RCD protecting the output of the inverter. So even if no earth connection, the RCD is going to trip when an earth fault occurs. If there is no RCD and the earth wire to the earth rod is broken, then yes, poor little Timmy gets a free ride to heaven. And yes it absolutely should be noticed and recorded on an EICR. It *must* be rectified.
Confused apprentice here, you said you had to disconnect the earth for the tncs system and connect the earth from the earth rod. Connect it where? in place of the TNCS earth? or just the earth bar and the neutral just hangs there empty in that terminal box?
So basically, disconnect the PME earth from the earth bar and make it safe, and then reconnect the new earth coming from the rod, back into that earth bar 🤓
@@corymac So you're going for a fully floating system with no connection between earth and neutral? That actually sounds like a good idea it's safer than earthed neutral but I don't believe it.
‘I’m feeling so American, I should probably check my cholesterol’ 😂😂😂😂
Lol haha
As an apprentice I appreciate videos like this, not only do you show the theory to it but then you show us a real world situation which is something I don't get in the classroom
Glad it helped mate!
This video is full of little gems. The labelling at 16:15. "interwebs" and "vacum", love it.
You're a born trainer Cory, seriously. If you ever give up being on the job, take up a position to train others at a Tech or equivalent in the UK. Loved this! Oh, and Timmy _(Timmaaaa!)_ is eternally grateful 😂😂
“Timaaaaa” 😂😂😂
You’re too kind
brilliant, im currently on my level 2 training to be a spark and this helps me so much its one thing learning these things but its another to see it being done in real situations. your passion for the job really shines through aswell, i hope one day i will be as knowledgeable as you!
Glad to help!
From watching your first video on artisan, following your music and watching oy channel. You’re are the master of all and learnt so much from you being an apprentice.
You are a fantastic presenter. Great clear electrical information and very engaging. Thank you
Wow, thank you!
You say you're not a teacher Cory but you certainly have a talent for it. I'm not an electrician but find your videos fascinating.
Unlike my old dad who, I swear, was immune to electricity the amount of times I saw him go: "oops, that one's live!" and walk away unscathed, I would not DIY but it's really handy to gain enough understanding to recognize a good electrician from a not so good.
So thanks for the lessons, I am enlightened. 😄👍
Thanks Jude!
An electrician that actually draws semi-decent circuit diagrams and actually sounds confident when writing equations up on the board; I am impressed. I truly am.
great video. whilst you were talking through the testing, i couldn't help but notice the labelling on the sockets - vacum and interwebs were my personal favourite 🤣
Really informative video! I'm no electrician but the way you've demoed this is 10/10
Glad you liked it!
In Oregon US, two earth rods are required now. I got away without doing that when replacing the mains (consumer panel?) since I re-terminated the original wire. I am not licensed, but allowed to do the work as a homeowner if I do permits and inspections. Passed on replacing main panel.
And this right here is how you do a video for the Trades. Brings back both the pride and respect so often forgotten ✊👊
Very well executed, and much appreciated. And I'm confident in your success, no Doubt!!!!
💯 thanks mate
Absolutely brilliant explanation! Videos are getting better and better. Please keep this kind of content coming.
More to come!
It’s good seeing the different ways things are done in different countries
Thanks! I like that too
Timmy should be internally grateful
Very interesting, this explenation helped a lot with validating every step I took in my solar installation, looking forward to the next video :0!
Glad it was helpful!
Gerat video Cory, just finished my domestic installer course, and struggling to get my head round several concepts, you've made things a lot easier with these videos.
And no-ones asked your peloton tag!
Great video!❤
We install alot of off grid systems Adding a genny gets intreasting.most victron inverters ypu can select eartth netrual relay as the bonding point.
Confusingly cory... the battery regs say to keep the pme earth in island mode!😅
Lesson number 4: if an inverter/charger is powered by both a battery bank AND the grid (or a generator), this whole ground safety connection scenario is a lot more complicated, and is highly dependent of the specs of the components.
Such as:
• does the inverter have a neutral/ground connection inside?
• does the generator have a neutral/ground connection inside?
• are you installing the right ground connections without creating ground loops?
But all of this would not change what happens for the ground connections for the AC output side of the system
Good man, i can thank you enough for your video(s). This was one of the clearest explanations on earth fault loop impedance. Thanks mate.
Glad it helped!
Great Video Cory love your approach to teaching stuff. But I do find the 'Generator room' a bit of a laughing nightmare i.e. the Victron is mounted on combustable chipboard, below which are a stack of Battery Packs, all sitting next to an oil tank! and you're worry about getting an electric shock. I would either have the owner move the solar system to the otherside of the room, or build a fire wall between the solar system and the oil tank.
There are alot of fail safes and changes still to be made. This is more of a proof of concept phase at the minute, there are ALOT more batteries, and at least 2 more
Inverters to come. Also, it’s in the remotest remote part of Dorset, and a good 70 metres from the house or nearest building, so at least if it goes pop, it’ll be a good distance from anything 🤣👍🏼
But fair points
Working for a DNO we install these earth rods regularly, unfortunately if you cut one of those rods you will find they are copper coated steel rods😅 but love the way you explain the theory behind the earthing and bonding. Brilliant video.
Great video. Was wondering how “off grid” systems treat grid connections when there is a power outage. I’m in the thinking about it stage re and off grid/ ups style so will be interested in how you plan this out. If I decide to press the button then I’ll be giving you a shout.
My inverter has an island mode function which requires me to install a new cable between my house and garage so im going to install an earth nest whin i dig the trench then convert the house to TT hopefully get below 20 ohm
Brilliant - I have a smaller Multiplus II here and was wondering about the earthing if I chose to not use it on grid/ess mode. Masterclass.
Great episode. As others point out, you’ve got a good teaching manner, not going to have students falling off the backs of their chairs because they’ve stopped following. Can you print a ‘vacuum’ sticker next time you are there? OCD etc.
Thanks Ian! 😂
If it's the same I've used @ 14:12 it's actually a copperplated steel rod. Had to do a temporary earthing and didn't get the rod all the way in so had to cut it off and noticed
not much classroom stuff really hits home with me straight away but your teachings do . bigup thanks and i look forward to the next vid . on a side note , what van did you get ? any good?
So glad to hear it! I ended up keeping the caddy, budget with moving houses and areas ( you’ll see soon 😉 ) restricted me.
Hi Cory, many systems installed are in island/backup mode and as long as they are G99 compliant, do not require a separate earthing rod and can use the tncs earth. Here is the extract fyi :
In island mode, an installation with EESS must comply with Regulation 21 of the ESQCR, and the PCE operates as a switched alternative to the grid. All live conductors, that is line(s) and neutral, that are to be powered in island mode must be disconnected from the grid. The installation may remain connected to the distributor’s means of earthing (where this is provided).
Earthing arrangements for island mode operation
In connected mode, an installation with a TN earthing arrangement (TN-C-S or TN-S) may use the distributor’s means of earthing. In a TT system, the consumer’s earth electrode is used - but care needs to be taken to ensure that this provides an earth of sufficient quality.
However, when the installation moves to island mode, it is important to make special earthing provisions.
Regulation 551.4.3.2.1 of BS 7671 states that, in TN systems, generators operating as a switched alternative to the public supply cannot continue to rely on the distributor’s means of earthing.
hi Bill, im curious on this one too. My system ( not installed yet) can go island mode everyday during a set period of time ( say 10:00 am - 15:00) . How can i have a separate earthing for only this period? ( does this mean i should not connect my battery / inverter to the main MET? or can i have 2 earth connections simultaneously ?
I think "To Live and Die in LA" was your best song. But "Dance Hall Days" was great, too.
These setups are so strange to me being in Canada, the supply connection here doesn't bring in a ground at all just hot and neutral, we always have to install ground rods or a grounding plate on every job , and then bond that to the supply neutral only at the first means of disconnect (main breaker, main disconnect) and we're done that's the only arrangement....
Having the earth connected to the neutral of the incoming feed, or having a separate earth wire coming in on the incoming feed is a better strategy for earthing than using an earth rod.
It is safer.
Using am earth rod is the worst way to provide earthing.
Firstly the earth rod gives much higher resistance/impedance than an earth wire, and secondly it is very much dependent on the moisture content of the soil, and that varies through out the year. So the Zs value is going to vary throughout the year through the seasons and hopefully it doesn't get too high.
Always great to watch a Corey video drop...been a while since your last upload...Great work mate🙂
Thanks Dude 👍 , more to come
As someone who is about to start electrical in college your videos are so helpful
Glad to hear it!!
Love this channel, learning and having a bit of fun, I like Timmy he needs to stick around 😀😀
Glad you enjoyed it!
In Belgium it's standard to have a TT-net, but the resistance should be less than 30 Ohms. (When taking the correct extra precautions, it can be between 30 and 100 Ohms.)
Great video and explanation on why we do what we do .Thanks Cory
Thanks for watching!
@@corymac always 👌
Ah that’s the video I wanted, I’m just doing the same thing for mine. What size earth cable did you use? I ran 25mm dam that’s a cable and a half In conduit. I want to see if I can go six rods deep just waiting for the adapter for my drill and hopping it can go that deep lol
Excellent video my friend! Great training techers 😉👊🏼
😉 Thanks mate!
you killed timmy! you b... loody did a good job of saving him! 😂😂
tbh, im not a sparkie but after this i now get the zs ze readings useage and the diff connection types (pme etc) bril cory! your a damn good teacher ! (and darn good sparkie too!)
Thanks Geoff!!!
At what point are you bonding the new earth to the inverter neutral or is that done in the inverter
That’s done at the inverter 👍🏼👍🏼
8:42 oh no timmy 😢 😂😂great video mate.
Your uploads make my day, thanks for your work 👏🏼
Happy to hear that!! It’s absolutely my pleasure
Im no sparky, but watching other videos, it appeared to be that if the water pipe and gas pipework were bonded to the earthing, then there was a possibility of the system still being TNC-S by virtue of the fact you share supply lines with your neighbours whom quite likely are TNC-S. Is this negated when both the water and gas are supplied in alkathene (plastic) type pipework? Also, i thought the earthing rod had to be 10 metres away from all pipes or cables? All still seems to be a bit confusing. 🙂
brilliant video Cory. Cheers from NL
I’m planning todo a off grid system. Solar & battery system. Biggest problem I have is I live in Finland and it’s practically winter half the year.
How would I create enough power to be off grid fully?
Are there any kinetic energies around you? Wind, water streams, tide, sauna smoke? It would be a challenge, but with behavioural adaptation, and a lot of batteries, I think it would be possible. Maybe even via the route of electrolysis
Build a nuclear reactor in your basement?
8:42 😂😂
Brilliant video!! Cory love your content!!
Question : what if i am on a TNS system and Installing a Hybrid Inv / Solar + Battery. ( i will potentially use my supplier and go completely OFF-Grid only during the peak hours) .( in which case i will still need the existing earthing system) therefore, do i still need to install a separate earth Rod or connection to the MET is sufficient ?
watchin in progress ... loving the whiteboard explanation. i'm a layman and it helped me a bunch. thanks :)
Do you think there is a need for a 100mA Time delayed RCD before the CU as would be normal on a TT earthed system or is that protection not required here?
Great video. Thanks for fully breaking it down .
You're very intresting and precise in how you convey yourself! Im a Refrigeration engineer and want to become a Electrician! Your videos are so entertaining :D
Problamtic in my situation. I am mainly runnng offgrid but at times I need grid to charge and that activates the earth bond to the mains but grid disconnected there is no earth wire for AC out in the inverter and I can only ground the chassis to my own common earth bar which is connected to the copper vampire stake in the ground…. I hooked earth to an AC plug for now but if I go back to mains then that equipment has no Earth, hmmm.
On the other hand, with an off-grid system where the inverter is contained within the building, there is no potential between you and the generating equipment until you install the earth rod. So would an IT arrangement more practicable for off-grid generation?
'merican here .. I've got 3 ground/earth rods on my property from previous buildings, ... GOTTA have 'em here.... And, ... TBH... We NEVER "liked" little Timmy, .. BUT, .. Your calculations, way of explaining things/Edgumacating me, ... are TOP Notch, ... Well Done "Sir" , ... I salute you.......
🦅 ⚡️ 🫡
Another great video Corey! Fun to watch and learning at the same time 👍
Glad to hear it!
Love your vlogs they are always something different and educational, Thank you.
Another great video. You and that whiteboard is like being back a college, just not as boring. How is Timmy? hope he recovered.
He’s a little shaken up, but doing well overall
Fortunately he only touched 49.999 volts.
Excellent content and explanation. More please.
More to come!
What would happen if you added the TT but kept the TNCS system connected as well?
Great question. In a usual situation it would be fine, and it’s rumoured the next regs update will encourage this ‘supplemented tnc-s’. But in an ‘off grid’ scenario, you must separate from the supply neutral and earth entirely.
Look at our MEN system in Australia. We have our Neutral from the Transformer tied to Earth & We also have an Earth Rod.
A TT earth connected to an existing TNCS system is in effect just another earth point on the PME (TNCS being a PME arrangement).
I think the reg's should encourage this - there are numerous advantages to having a local PME point (i.e. a TT earth) at a property - primarily it gives you another layer of protection if there is an earth fault on the DNO line....which can be a disaster with TNCS in scenario's where there is no other form of effective earthing via the utility bonding (plastic incoming water pipe, no mains gas at the property)
Imagine a scenario where the incoming DNO earth is somehow broken, yet the live is still connected - with TNCS combined neutral earth, this will in effect make any externally conductive earthed appliances and your sinks, taps etc to be at mains potential! where there is no effective local earth to ground the floating potentials.
Great video Corey! Followed you from the start at artisan. You really excel in explaining things and would be a great trainer in future! Keep it up.
Thanks a lot Danny 😁👍
That's really interesting. Im looking at a hybrid system (without grid-tie) so imagine I'll need a local earth.
I've got a load of 6mm wire for the panels' earth but is that thick enough for the external earth?
Fantastic Cory! Theory and practice. And cool real world "stuff". I look forward to the next episode. Cheers
Thank you for the explanation very interesting
You’re welcome Dave!
Hi Cory , when filling in your Zs for you circuits , would you add the R1+R2 to the 4.55 ohms and have worse case scenario or would you test Zs and obvs have a lower value. Some would argue Zs is irrelevant now with RCD protection.
Check T41.1 and 411.3.2.4. In the regs ( BS7671 ).
The maximum Zs when using RCDs for fault protection in a TT system is based on 411.5.3 and Table 41.6 411.5.2 it does say that an appropriate overcurrent protective device may be used on a TT system for fault protection if the Zs value is permanently low.
@16:17 - What's a Vacum?
It's a partial vacuum: it's missing something...
Love the video, didn't really get a clear understanding of the why ie why is the provider earth not appropriate when you are in island mode??
Because in island mode the electrical system using the inverter is not connected to the grid.
What you are always trying to do is provide a return path for the current to get back to the source from where it came. It has to do that, otherwise you don't have a circuit, and if you don't have a circuit then no current flows, and the breaker does not trip.
If you are in island mode, that source is *not* the grid, so the grid earth wire does not help you in anyway whatsoever.
Your earthing has to take the current back to the source from where it came.
If there are batteries being charged by the solar panel and those batteries are providing power to the inverter, then the return path is back to the inverter (and ultimately back to the battery).
If there are no batteries, solar panels only, then the fault current needs to return back to the inverter, and then it goes back to the solar panel.
A circuit is required for current to flow.
That's a closed loop from the source along the cables to the loads, back along the cables and back to that same source.
The inverter acts as an AC voltage source.
Ok tha ks understand the physics there, but when not connected to the grid for supply you will still be connected to the provider earth? If, as in my instance, I can see my local transformer (30 yards away on a pole) and I know there is a provider earth below that, then am I adding anything by switching to a local TT other than probably increasing my earth resistance? Is there a worry about PEN faults with an off grind inverter? Can anyone explain the benefits / downside of just adding a local TT to your earthing without isolating from the provider earth? Feels like that would maintain lowest cost route back to source in all scenarios? Thanks
I love Kewtech, what do you think of it? Tell me 👇🏼
I should get 1 r they more helpful than the megger n if so I’ll get rid of my 1741+ ⚡️💤
I got one after seeing you using it happily, I have the model down from yours. But still, no regrets. Great kit
Really interesting video Cory. As others have said, you would make a great trainer.
Lunch break videos are sorted for a while, thanks keep up the good work 👍
I hope it’s a decent lunch 🥙
Well done Cory nice episode , please give more details of work, because someone follow u mate
To answer your question. In addition to extraneous conductive parts being bonded to the main earth then the other two are:
The requirements of ADS are met for the circuits
All circuits within or passing through the location are protected by 30mA RCD (or RCBO/AFDD these days).
Nice one as always Cory love watching your content 👏😎🇮🇪
Awesome thank you!
Interesting topic! Have a question if you don't mind, are you changing from tncs to tt system?
In this video I am indeed!
Awesome video, wish I had you as my teacher at college!
When doing your ze test for the rod you mentioned you’re looking for a value below 100ohms. I always thought the TT highest value was 200ohms? Has something changed I’m not sure about?
Hiya. In an off grid system you wouldn’t have the return path to the transformer earth. The Victron inverter has a relay that bonds earth and neutral together thus providing your return path. Effectively you are creating a TN-S system. The relay opens when you connect to the grid.
It is not quite that. You might have a path to the earth of the transformer but it is not a return path for the current, as the current did not originate from that transformer.
So whilst there may be a physical connection there, it doesn't provide a return path.
@4:02 Pauline in „The League Of Gentlemen“ has pens, too... 🤣🤣
Hi Cory,
Nice video 😊
What happens when next doors gas & water bonding is metal pipe work & linked to your properties TT supply & they are on a tncs supply ?
Or this ‘TT’ system is close enough to the transformer earthing to be affected by it?
In this scenario I’d probably recommend a plastic pipe break be installed. This property had plastic incomers and it’s own partly off grid supplied so wasn’t an issue.
Cory Milwaukee Man Mac’s wipe board is out again shame you didn’t have a full set of colours. Maybe if you had the yellow one you could of been Timmy’s saving angel. 😂 Mockery is my only option because the Math went over my head 😊
Poor Timmy.I thought he had fallen down the well!! Now you telling us he is touching the frames of ungrounded electrical equipment. Where is Lassie when you need her?. Great tutorial Cory!! I always like your cardboard classroom. Groundrods are common here in the states with only one common path to ground at each site location. It felt like we came to the duscussion without a prelim. of why you are doing the change. When you say mains .do you mean electrical utility supplyer?. Your vlogs always require a second viewing. Seperate and apart from the two moons over Myhammi what kind of Van did you get?. Happy Easter,!!!!!
A potential upgrade might be an earthing mat - a big ol copper plate that gets buried. Understandably not as convenient but worth leaving as a note for the homeowner if they have earthworks planned.
That rod is a good length!
Check out a Condudisc!
Given that the impedance is down to less than 5 Ω in this case, no upgrade is worth it.
The impedance is more than low enough to trip a breaker or RCD.
But as an earthing solution where the resistance is coming out too high, yes, it is a good approach.
A potential upgrade would be increasing the supply voltage from 230 to 400 😭🤩🤩🤩
@@deang5622 I was thinking in terms of how many years of use rather than the immediate state electrically when it's still quite new. Degradation over time.
Everything is TT in France. Multiple rods and 10m long 0.5m deep buried bare copper chunky stranded cable is sometimes necessary to meet the test impedance, made by the Consuel (state quango) site visit inspection.
That is totally crap.
Great video Cory... I'm all Earthed Out now🤯
One thing though about Gas/Water bonding... you forgot about MDPE incomers 🤫
Oh, and by the way, that kewtech is anything but basic... recently helped my nephew get one which like you he loves and at a 'bag of sand plus the dreded' ain't cheap given his lack of income at the moment.
Anyway great video and keep doing what your doing. Respect 👊
Great point!
The incomers here didn’t apply, they were all plastic
Amazing content,do keep it up Cory.
Appreciate it!
Fantastic work and a great explanation. Keep it up.
Hiya mate, I'm sure you were on another channel before this. Its great what you are teaching so I can learn it all from you ;) I'm a plumbing and heating engineer and just installed solar thermal. The customer has solar pv but they asked me about batteries. What batteries should they choose?
I said there are a few TH-cam channels out there hut only a few like yours include the safety aspect and explain why we have to do it that way in England. So I want to share your channel with them. Do you have any recommendations please?
Awesome bro! Learn a lot from your vids, soon starting my own small Electric business in Belgium :)
Go for it! You won’t regret it
I see you haven't lost your angle drilling skills, Jordan must be proud. Another interesting learn with Cory. I've always thought sparks were the cleverest trades.
Absolutely, as a spark I agree entirely 😁🤓😉
Great video mate love your content! One quick query though where does it state 100ohms or less for the zs of tt system as the maximum permitted zs for a tt is 200ohms?
The limit of 200 ohms is NOT the value of Zs. You are mixing up the total earth loop fault impedance with the impedance of the earth rod connection.
The 200 ohm limit is on the impedance of the earth rod itself.
Table 41.5 in the regs says the resistance should be as low as practical. There is no hard limit of 100 but obviously 100 is better than 150.
And the key value is the Zs value for a 30mA RCD if the circuit is protected by RCD is 1667 ohms and that is Table 41.5 too.
Interesting work. Is there a requirement for measuring the earth rod resistance, and a minimum ohm value for it to be effective? Many farms are on TT network and I remember the gravel round the rod was not good at all.
Yes there is. IET says no more than 200 ohms. IET says this:
Table 41.5 of BS 7671:2018+A1:2020 states that 1667 ohms is the maximum earth fault loop impedance value where an RCD with a rated residual operating current of 30 mA is used. However, it is important to take into account the ‘*’ referring to note 2, which states the resistance of the installation earth electrode should be as low as practicable and a value exceeding 200 ohms may not be stable. But what does not be stable actually mean?
Note 2 of Table 41.5 refers to Regulation 542.2.4 of BS 7671:2018+A1:2020, which states ‘The type and embedded depth of an earth electrode shall be such that soil drying and freezing will not increase its resistance above the required value.’
The main factor affecting resistance to Earth of an earth rod is the depth of installation. It is appreciated that this information is difficult to obtain, but to mitigate the effects of the soil drying out, the earth electrode should be installed at a depth sufficient to reach the water table of the soil to remain effective.
What effect does temperature have on soil resistivity?
Temperature plays a big part in soil resistivity, when the ground freezes, the resistivity increases substantially. An earth electrode which is installed during moderate weather may become ineffective during winter.
Table 1 indicates typical resistance values per metre for various temperatures for assumed conditions of 15.2% moisture content sandy loam. If the soil temperature varies from 20c to -5c, the resistivity increases 10 times, from 72 Ω/m to 790 Ω/m. This is why the note referring to 200 Ω may ‘not be stable’ is so important.
Great content as always keep it up !
What made you go for the kewtech kt66dl? I was considering it myself but wasn't sure.
Another cracking video Cory. Educational and interesting. I bet Jordan misses you at Artisan. 😂
Hope so! 😉
Not an electrician so genuine question… if we have RCD’s that trip if the line and neutral aren’t balanced, how come we actually need bonding anymore? If the current wasn’t all going elsewhere and not back down neutral then rcd would trip?
Absolutely excellent video!
Thank you very much!
Cory, I was speaking to a fellow sparky the other day, and he said he went to change a socket front at a property which was off grid, with a solar battery array, and a back up generator to charge the batteries. He found there was no earth rod, and his tester wasn't picking any form of earth up. he spoke to the solar company as it is a recent install, and they said there is no requirement to provide a supply earth, which I found baffling, as surely that is extremely unsafe, and the RCD wouldn't operate?? Am I right?
Absolutely that is not true. There is a requirement to provide an earth, it sounds like a very dangerous install. If you would like me to take a closer look, email me some more info & pictures cory@oyelectrical.com
Cory, if you ever want to change career and become a trainer, you’d smash it. A proper natural at explaining things well.
Not a sparkie and just curious, what protection in this case if someone digs up the concrete and cuts the new earth, would that kill Timmy ? and would it only get noticed on EICR?
No it wouldn't be because there is a 30mA RCD protecting the output of the inverter. So even if no earth connection, the RCD is going to trip when an earth fault occurs.
If there is no RCD and the earth wire to the earth rod is broken, then yes, poor little Timmy gets a free ride to heaven.
And yes it absolutely should be noticed and recorded on an EICR.
It *must* be rectified.
Hi from down under, its interesting watching how the UK system are completed
I’ll have to come down and see how you do things 😁🏄🏻♂️
@@corymac sounds good
How are you finding the Tech XL I’m thinking of getting one as my Pro PAC is a little too heavy.
Confused apprentice here, you said you had to disconnect the earth for the tncs system and connect the earth from the earth rod. Connect it where? in place of the TNCS earth? or just the earth bar and the neutral just hangs there empty in that terminal box?
So basically, disconnect the PME earth from the earth bar and make it safe, and then reconnect the new earth coming from the rod, back into that earth bar 🤓
@@corymac So you're going for a fully floating system with no connection between earth and neutral? That actually sounds like a good idea it's safer than earthed neutral but I don't believe it.
@@petehiggins33 No it is not floating.
@@deang5622 Of course it isn't, I don't know what I was thinking.
@@petehiggins33 It's difficult to get your head around these things unless proper and complete diagrams are presented, which they rarely are.