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EARTHING AND BONDING - SUPPLEMENTARY AND MAIN BONDING DIFFERENCES - HOW DO THEY WORK & KEEP US SAFE?
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- เผยแพร่เมื่อ 16 ส.ค. 2024
- We are frequently asked about bonding and earthing and what is supplementary bonding, so in this LearnElectrics video we will look at this important safety subject.
The sort of questions we are asked might include …
What is the difference between Earthing and bonding?
What is the difference between Main Bonding and Supplementary Bonding in a house?
And how does bonding protect me?
Determining the differences between earthing and bonding often causes a little confusion when new to the trade or looking on as a DIYer or handyman. Especially as they use the same green and yellow cables and don’t really seem to do anything.
It’s not uncommon to visit houses where the bonding has been removed by the householder because it “was in the way under the sink and anyway, nothing has happened by taking it off”. As electricians we should be reinstating these connections for the future safety of our customers.
It’s like seat belts or air bags in your car.
You don’t need them until you need them. And then you do!
To view all of our videos type in LearnElectrics all one word into the TH-cam search bar.
This is video No.182 on our TH-cam channel where we have videos on a wide range of electrical topics.
I wish the books were as simple as this Genius. Dave you are an excellent Teacher in the Electrical field
Thanks for the great feedback. I try my best, spread the word. Thanks for watching. Dave.
Wow! This is simple but revolutionary teaching. Like so many others ive also struggled in getting my head around this. After watching this once its unbelievably clearer and ive been to 2 different electrical training providers in the last couple of years. Goes to show how they fly through the basics expecting you to grasp the concepts. Thankyou so much ive also taken photos on my phone to put in my file under the earthing and bonding section.
Glad it was helpful. I try to make one video on one subject and teach it without assuming that ""everybody knows that""
Thanks for your comments and support, appreciated. Dave.
Amazing content, it's much clearer then in books 🙏
Happy to hear that. Appreciate your comments and thanks for watching. Lots more to come. Dave.
Thanks a lot for an in-depth explanation for dummies like myself. Love your channel❤
Happy to help and thanks for watching. We were all dummies once, don't under-rate yourself. Learn a little each day and even in one year your knowledge will be so much better. What will it be like in 5 years, 10 even. Dave.
Best videos I’ve come across. And I’ve watched a few. Explained simply and clearly. Last one I watched was earth fault loop impedance. Again another great explanation 👍
Thank you Bobby, and thanks for watching. appreciated, Dave.
Just looking through the comments and can’t agree more. The earth potential with main bonding is something I’ve always half understood. Knew its importance and understood about the earth fault path but couldn’t get my head round the difference in potentials. Actually can’t believe how simple it is. Very thankful for your video.
If it has helped, the video has done its job. Thank you.
Thank you ever so much better than class room to be honest 👍👌.
You would have enjoyed some of my classroom sessions. Love your colourful picture. dave.
I really found it hard to get my head around earthing arrangements in genral, this video was amazing and gave me a clear and better understanding on how each cpc system works. Thanks :)
Glad it helped, thank you. Dave.
This made loads more sense in helping to understand the potential difference of an exposed conductive part and extraneous in an earth fault when bonded.
QQ - to clarify, in the instance of an earth fault, all cpcs / bonding will become live with say 230 volts (as they are all at the same potential, and all connected to the MET) for the period of time it takes the protective device to operate?
e.g. 0.4 seconds
Correct. If you are touching two separate pieces of bonded metal work, left hand, right hand, say. Then they will both be at 230 volts. 230v left minus 230V right equals zero volts across the body.
Thanks for watching.
As always very informative and well executed.For any learner new to electrics these video would help tremendously.Thanks and keep them flowing 😃👍
You are welcome Martin. Your comments greatly appreciated. Thank you. Dave.
Just a brilliantly clear explanation of what was before this a bewildering jumble of words. I understand this now after the one watch! Of course, I will watch a few more times, but I grasped this tonight. I struggled with this before. Well done and thank you.👍
Glad it helped. the learning process never stops. lots more to come and over 200 videos on the channel and website.
great contents
Thank you, appreciated.
Another fantastic explanation. Thank you Dave
Very welcome and thanks for supporting the channel, appreciated.
Brilliant as always.
Glad you enjoyed it and thanks for watching. Dave.
Thanks again Dave, always Clear and precise well explained, keep up the good work.
Thanks, will do Anthony. Thanks for the support.
Thanks again , I read the regs then listen to you and get a better understanding
Excellent idea Andrew. The experts do say that combining learning methods is the best way to fix information in memory. Thanks for watching. Dave.
Thank you once more!
Appreciated. Thanks for watching. Dave.
You used 10 minutes to convey a world of information so simply and clearly.
Glad it was useful. I try and cover just one item or topic per video. Thanks for watching.
Best explanation 👌
Thanks for the feedback and thanks for watching. Dave.
Thank you very much, ur videos helps alot
Glad to hear that and thanks for watching, Dave.
Great video, learning lots. Thanks Dave.
Glad you enjoyed it, thanks for the support.
Well and clearly explained and visualised.EXCELKENT ,BIG THANK YOU.
You're very welcome Vachik, great feedback, thanks. Dave.
As always, just couldn't be explained any clearer, thank you
Great feedback, thank you.
Seriously mate, very very well explained!!! Thumbs up and subscribed xx
Thank you, great feedback and truly appreciated. Lots more to come. Dave.
Thank you another one for my mental toolbox.
Thanks Anthony. Every day is a learning day. Dave.
thanks for your very helpful video as always.
Great job by learn electric.
Thank you, really appreciated comments. Dave.
Thank you very clear and informative.
Glad it was helpful and thanks for watching.
Thinks dave your channel is geant school i m verry thinkfull because i find this channel
You are most welcome my friend. Thanks for the support. Dave.
Excellent, you explain very simple way with drawing.
Thank you, much appreciated, Dave.
With modern consumer units, and everything (generally) having additional protection being provided by default by a 30mA RCD/RCBO nowadays.
Supplementary bonding is becoming less common. To be honest it always was a bit of a faff and it looked unsightly, to run a 6mm earth around all the exposed & extraneous conductive parts in a high end (expensive) bathroom.
So supplementary bonding does seem to be a dying art.
Great video Dave👍
Agreed, I hated the good old dusty supplementary bonding tag that connected onto the rad copper pipe. When I re did my bathroom I reconnected it under the floor out of the way, all the copper pipe touch anyway so even if it was disconnected there would be a reading as all copper pipes touching
Agreed Mr B. Especially when the bathtub was one of those fancy jobs in the middle of the bathroom, nowhere near a wall.
Good idea, Thanks for the input. Dave.
@@kingofthetrowel1725 The point of them being exposed is so that they can be checked & serviced, hiding them under the floor prevents discovery when the next inspection is done. All screw terminals must be accessible as copper expands & retracts with the change of temperature & vibrations. RCD protection (assuming a sufficient continuity test proves this) nulls the need for sup bonding.
Inspections are becoming more & more necessary. It won't be long before it is required for a buyers report. So it may not matter now but it may in the future...cross that bridge later
Best explaination ever , and interesting
Thank you for the feedback and thanks for watching.
great video, well explained
Glad it helped Nigel. Thank you.
excellent video its very helpful do more explain and image. thank you
Glad it was helpful Azizur, thank you. Dave.
How comes you can explain in around 10 minutes what my tutor unfortunately does in weeks. !! This video was far more informative than sitting in a class. 👍 well done . Subscribed 👍
Glad it was helpful and thanks for watching. I try and get just one topic explained per video and always put your learning first. Lots more to come, Dave.
An RCD with a residual operating current of 30mA obviates the need for supplentary bonding since a shock situation will result in the disconnection of the circuit.
Absolutely correct. As it says in the video, they are both forms of additional protection, Thanks for watching. Appreciated.
@@learnelectrics4402This was an excellent video with clear English and no inane, superfluous, distracting muzak in the background. I like to consider myself a knowledgeable sparkie. I'm never too old to learn though and this was informative.
very clear explanation with good drawings you can publish book i will buy it
Thank you so much, a few have asked, but its not happened yet. Perhaps I should. Thanks for watching.
and just like that...I get bonding and earthing👌👍
If it helped, the videos done its job. Thanks for the comments.
Excellent video
Great feedback and great support. Thank you.
excellent as usual 👍
Thank you Brian. thanks for supporting the channel. Dave.
Great video I know too many sparks which struggle with this
Exactly Reece. Thanks for watching. Dave.
Thanks for the video. As an adult learner the topic of supplementary boding was difficult for me to grasp (no pun intended). I see from other comments about RCD protection etc that SB is not required on modern installations but an issue that still confuses me is how to determine whether a metal accessory is actually an extraneous conductive part or just a piece of metal?
Is it "earthy", is there a possibility of it making a connection with earth at some point - water pipes that go into the soil or touch it, for example. That would be an extraneous conductive part.
Now consider a metal shaving mirror. Would you bond that? Or the metal can of underarm deodorant? They are metal too, but they don't have a path to earth. Hope this comparison helps. Stick with it, it will make sense. Dave.
@@learnelectrics4402 Thanks for taking the time to reply. I understand what you are saying but what if it's not as clear cut as your two examples. Is there a test to see whether it is or is not an ECP?
Great video as usual. I do have a question about the reason for bonding though. I understand the point of bonding if you touch the cooker and kitchen sink taps simultaneously but are there any other reasons for bonding? I apologize that my question may seem basic and obvious but I always thought it was for if lighting struck.
Have a look at the video on the link below. Bonding is to prevent differences in potential between simultaneously accessible metal work during a fault. Lightning protection is a whole subject on its own. Hope this helps and it doesn't matter how basic the question, ask it.
th-cam.com/video/EYj9mvOfF_w/w-d-xo.html
@@learnelectrics4402 thanks so much
Generally good video. A bit of a hiccup at about 7 mins when you slipped into suggesting that 230V "would flow around...".
Q. What would you do with the supplementary bonding cable in say a bathroom if there were no exposed conductive parts but there were extraneous conductive parts? (I was asked this on interview at SEEBoard way back in 1988 and the three interviewers ended up disagreeing amongst themselves!)
For clarity, as there are no exposed conductive parts then there's no CPC available to connect to.
I can imagine that made for an interesting interview. I would have thought the interviewers would have decided on questions and answers beforehand. I'll look at 7 mins. Thanks. Dave.
Is there a path back to earth? That's what we are concerned with. Would you bond a metal shaving mirror, or a metal disabled handle next to the toilet? Great input, thanks.
What I don’t understand is why or how outbuildings have to have a separate earth path!A site I tested with a electrician noted as a code 2 that the large steel structure glass house with its own db supplied by swa from the main building & has a cpc bolted to the steel & connected to the db earth bar has no earth rod for all the steel work. I tried understanding but cannot work out what the issue is if the swa is providing a path & a cpc bolted on to the steel and connected to the earth bar in the db. What could be the issue here!
A lot depends where your feet are and what you are touching when a fault develops.
As an adult learner, thank you for such a clear explanation of a subject I struggled a bit to understand.
Quick question: My house has a TNS system where the main earth conductor is made of what appears aluminium without any sleeve.
Does it need replacing?
Thanks.
If its undamaged then no. Aluminium becomes brittle, if you try and move it it can start to crack.
@@learnelectrics4402 thx
Thanks, John 👍 brilliant.
I have a question
What is the relationship between fire alarms and surge protector devices?
Install the fire alarms as per manufacturer instructions. A quality fire alarm should not be affected by an spd as the spd is a passive device until it detects an over-voltage.
What's the bonding in the hot press called?
Not too sure what you mean here.
Hi. I have just come across a 10mm earth cable that runs from the water inlet to the CU that is buried along and under the bottom of the skirting board for a distance of 3.5 meters from a total distance of 4.5 meters. Is this permissible? Pardon my ignorance.
is it earthing or bonding? What edition of the Regs was it installed to? Lots of factors to consider. 4.5 metres is not an excessive length and at 10mm it will take well over 1000A of fault current if we are talking about a 0.4 second disconnection time. If your PFC is less than 1000A, the breaker will disconnect before the cable is damaged.
Have a look at this video, it will help.
th-cam.com/video/xtDId-g7GjU/w-d-xo.html
@@learnelectrics4402 Thanks Dave. Its an earth cable. And was installed before we arrived to complete other works. So we dont know when it was done. The householder has only recently moved in. After the previous owner died.
I will of course watch the linked video.
Thank you once again for the brilliant content you provide.
👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍👍
Nice video
Is Supplementary bonding regulatory if bathroom pipe work is plastic? I don't think so?.. or copper pipes connected with plastic push fit joints?
If there are "earthy" parts as per the video.
Take a look at this video which covers the very correct point you make. Thanks for the input, appreciated. Dave.
BONDING PLASTIC and COPPER PIPEWORK, on the link below
th-cam.com/video/EYj9mvOfF_w/w-d-xo.html
what if you grounded by being bare-foot and touch a bonded surface that has a ground fault on a supplementary grounded system?
If the installation is properly designed and constructed, the protective devices should operate before you are in danger.
Does a metal pipe (gas/water) coming up from the ground (so sort of 'earthed') still need to be earth bonded?
Take a look at the video on the link, it will help you to decide. Thanks,
th-cam.com/video/nLl1qgyB7Mk/w-d-xo.html
Great explanation, could you cover bonding at gas meters as I've seen never builds that aren't bonded in the gas box. It would be good to know why.
Great suggestion Lemmy, it's on the list now.
@@learnelectrics4402 top man
Just to clarify, when everything connected to the met rises in potential , would you receive a shock if u were to touch some metalwork that has risen in potential whilst you’re in contact with true earth??
Depending on the voltage difference, yes you would. Hope this helps.
Mostly an excellent training video item but I have to disagree about the potential on an appliance, in this case the cooker, during a fault. If the appliance is earthed, the casing will not rise to the full mains voltage (230V) but to a potential determined by the resistance of the supply circuit Ze + (R1), the circuit CPC and the earthing arrangement (R2). If these happen to be equal, then the potential on the appliance will be half the supply voltage. Ze + R1 and R2 form a potential divider and the applaince casing will be at R2/(R1+ R2) * 230 V. This is still a potentially dangerous voltage and the purpose of the main and supplementary bonding is to tie the potential of all the exposed conductive parts and extraneous conductive parts together as closely as possible to minimise the potential between them during a fault. The difference wiil depend on where the connection between the bonding and earthing conductor is made, but should always be of such a low resistance that any potential is non-hazardous.
Thanks for the input and thank you for watching.
Bonding becomes an issue in case of a PEN-fault. Then there will be almost full mains voltage at any earthed appliance and normal methods like earthing and RCDs do not prevent this. Of course spreading the voltage to the pipes is a double edged sword and could cause its own danger but is as a whole is safer than without bonding.
Hi there, I'm just about to sit my 2365 unit 203 exam. I was wondering if you recommend any videos/websites for example questions and answers? Thanks and keep doing what you're doing 👍🏻
Lee, not specifically on that unit but I can bet you'll get questions on the videos below, especially bathroom zones. What zone is the bath? for example. Why do we have prescribed safe zones? and so on. A little bit of studying every day is better than cramming it in the night before. And don't just answer practice questions in your head, write the question and the answer, it helps to make it stick.
Good luck. Dave.
Bathroom zones
th-cam.com/video/ZktUCaFSH6o/w-d-xo.html
Electrical safe zones
th-cam.com/video/lThW98NtKV8/w-d-xo.html
Earthing and bonding
th-cam.com/video/Fdqb2CEOENw/w-d-xo.html
@LEARN ELECTRICS thank you for taking the time to reply, I really appreciate it. I'm sure I'm stressing about nothing 🙃
I'm first to comment here, Dave
Much appreciated Daniel. Lots more to come.
How can there be 230v in cooker casing when the cooker CPC is connected surely MCB will trip meaning if you touch the water pipe you will not get 230 v across your body as the cooker MCB will have tripped do you mean if the cooker has no CPC connected or broken this will happen
Have another look at the video. We are talking about bonding with the cooker cpc connected. Dave.
Keep me right here I thought if the cooker CPC is connected to casing it would carry the fault current and would clear the fault trip rcbo so you could not get a 230 v from casing to water pipe as casing would be dead Cheers
Thank you for a clear explanation, in the example of the person at the cooker and touching a water pipe , if there was a plastic main entering the building , is it the case that this situation could exist ?
Have a look at the video on the link below, this will explain a lot.
Also, watch out for our video in two weeks about making decisions to bond or not and what resistance values to base your decisions on. Meanwhile ...
Bonding plastic and copper pipework
th-cam.com/video/EYj9mvOfF_w/w-d-xo.html
I'm first to watch it
That's good. thanks for watching.
A good set of videos ... but you should say 'mm squared'. I know very few electricians do because they are lazy. If you are educating, you need to be wordperfect
I think Dave is right. I’ve always been taught it is 2.5 square mm for example. If you look at a piece of 2.5 copper what Dave says is correct.
The conductor sizes are square mm, it is the surface area. Think about a 10mm twin and earth cooker cable. If it was 10mm squared it would have a surface area of 100 square mm, making each conductor almost 12mm in diameter. And 10mm conductor is not 12mm in diameter. The round surface area is 10 square mm. It confuses many but that is the way they write it in the regs book. Thanks for watching. Dave.
Thank you for your support. Yes, you are correct. Much appreciated, Dave.
Hi Dave ,Excellent as ever.Dave I was wandering in case of the cooker and the water pipe, instead of bonding the water pipe to the main earthing bar could we just connect it to the cooker's CPC as in supplementary bondig to save time and material? Big Thank You.
Not really.
The cpc is a cpc, the bonding cable is a bonding cable.
I know they all go back to the Earth bar but the boffins regard them as two separate cables with separate functions.
CPC is there to make an earth path during a fault.
Equipotential Bonding is to make all metalwork the same "equal potentential" by "bonding" them together.
Hope this helps, always try to follow the book.
@@learnelectrics4402 Thank you so much for your reply. I Appreciate that.Your programmes are much more helpful than the course I am enrolled with , but I don't give up and like to learn more.