Part 3 covers supplementary equipotential bonding and the most common location it is required - bathrooms. Earthing part 1 : • Earthing & Bonding - P... Main bonding part 2: • Earthing & Bonding - P... Website: xo4.uk/?sPp
Thanks JW for your clear and concise videos, always informative with plenty of detailed explanation of every subject covered. From a working electrician with 49 years experience in industrial commercial and domestic installations, still learning.
Great videos!! I'm pretty new to the game recently passing all of my required exams and these videos are a real bonus.. Not only for additional information but, for revision and clarity.. Please!! Keep them coming!! Thanks!!
Youl George you think have problems there look at wat they have go through over here in the u.s.. just get that electricain lic. they have to deal with 3 - 4 years of schooling.
Boilers when I was working on the 17th Edition Wiring Regs were always bonded as the integrity of the pipework "could not be relied upon" this was due to washers and corrosion of pipe joints at the Boiler and NICEIC Inspectors were keen to see such work completed. With the introduction of RCD;s I personally see no need to have any Supplementary Bonding within an Installation. So very interesting to listen to you John Mr Spence Eng
I've came across this argument myself. But I don't think it holds water - literally. The pipework is solid copper with either brass compression fittings or soldered joints. We could use plastic joints - but not within 1m of the boiler. In terms of corrosion of the pipework or its fittings (or the internal parts of the boiler) these would almost certainly fail to contain water/gas before they fail to be sufficiently conductive. Now frankly the customer is going to notice (and do something about) an escape of gas or water long before they notice the failure of a chain of earth clamps and wires. And of course we can look at the boiler itself as a class 1 appliance. It is compliant with BS EN 60335-1 and therefore all conductive external parts ( including the places where the incoming pipes are connected ) are connected to the CPC. This arrangement isn't subject to the judgment of some previous tradesman but inherent in the design of the boiler and validated by the notified body (as gas appliances are subject to the notified body process). Quite simply the internal bonding between those pipes is probably more reliable (even in the presence of corrosion) than any electrical termination within the wiring installation itself.
John, You mentioned underfloor heating for the bathroom. If the Underfloor Heating is under the floor tiles - is the Underfloor Heating then considered outside the Bathroom. Similarly - if there is a resistive switch for switching the lights mounted behind a tile - then is this also considered to b e outside the Bathroom. Resistive switches in my opinion are a much neatere switching method compared to the banarl ceiling mounted pull light switch. Taptile is the type of resisitve switch i am refering to. BTW - Great knowledge shared.
Hi John, got a quick question hope u dont mind answering it. Is it ok if u dont link the shower and the light fitting in the figure u showed in your video since they are already linked in the fuse box on the earth terminal. Thanks
The electrical connection cpc is connected in the shower and at the consumer unit but this is talking about providing an additional connection & bonding the pipe. Since the pipe connection in a shower is often plastic you could end up with a brief potential difference between the shower and the pipe. Or not brief in some situations. I lived in a house that didn't have and rcd once and when the shower went wrong the was 140v between the shower handle and the pipe. The current wasn't enough to burn the fuse wire but would be enough to possibly kill
Thank you so much for your great great videos . If possible , please do more films like" "TN-C-S Danger-Broken Pen Conductor" and "Shared or Borrowed Neutral ... ". Thanks again and God bless you.
Fantastic and well structured series. Question to John; I have refurbished house with all plumbing in plastic. But I have copper tails to help tap and boiler connections. Would these copper tails need bonding?
Shouldn’t the pipes already be bonded though from the main bonding? And say before it came into the bathroom it was plastic and then copper do you need to earth the pipe?
Great videos as always John, could you please clarify the following, you said that pipes in a bathroom need bonding but pipes at a boiler do not as they are already bonded. If this is the case then I am assuming that given a property has the combi boiler, then there is no reason to ever have to bond the pipes going into a bathroom? Looking forward to a reply, thanks
Hi Jonn In IEE regulation 701.415.2 (v) states all sup bonding may be omitted providing "All final circuits of the location have additional protection by means of an RCD in accordance with regulation 701.411.3.3" Does that mean each relevant individual circuit in the consumer unit feeding the bathroom has an RCD or 1 overall RCD protecting the whole bank or MCB`s Thanks
From the part 2 video, if the main water supply in to the building is plastic but the house water distribution is via copper pipes earth bonding to the water supply is not required. All wastes are in plastic. So am I correct in assuming that supplementary earth bonding is also not required as all pipework is effectively isolated from earth.
Hello John. Top video. I have an old house, which was rewired professionally in 2000. Hagar Split load distribution board. The plumbing is 99% plastic. incoming blue plastic, then a brass stop cock under the sink then Hep20 throughout. the heating system is also plastic apart from the LPG gas supply, the first 3m of flow and return are copper. And yup, these pipes are supplementation bonded ha. We built an extension to get a proper size bath. again all plastic pipe, apart from chrome stand pipes next to the bath ! We asked a local electrician to do an EICR as we may let as my job is relocating. the electrician has recommended we bond the bath stand pipe !!!! I have taken from your tutorial that this is not required as long as all circuits are RCD protected. fitting a dual load RCD protected board would be less intrusive that bonding the bath taps. Would appreciate your opinion. Thanks
I was called to a problem with a tagging (anti-theft) system installation in a chain DIY store that kept alarming at random. I could find no fault in the installation it's self, but I got a belt when I touched the steel door-frame of the building whilst leaning on the tubular steel collision-protection bars set in the ground outside the door. Metered it at 230vac! The steel frame of the building was connected to the floor re-bar, (as part of the lightning-protection?); the local building earth was such high impedance (O/C) that everything structural/metallic in it was floating. Company electrician informed, store shut until it was fixed, fault then disappeared.
Hi went to job in a block of flats and tennent said he was getting a shock of the taps in his bathroom when he had no shoes on and touched the taps I did confirm this when I arrived at the property I then decided to isolate this by turning all the power of to the property but the fault was still there and still could get a shock of the taps and pipe work under bath I noticed there was a old lighting conduit under the bath for what I believe is the flat below I then went and knocked on the flat down stairs and got assess to the property and isolated there lights and the pipe worked in the bathroom can now be touched and not be electrocuted I'm confused as to why the rcd in both properties did not operate have u ever come across this scenario ?
jason green If the current was less than 30mA the RCD would not trip, but it is still possible for a person to feel it as a shock, particularly in a wet location like a bathroom.
Hi JW, if you're saying that the cpc under the boiler is superfluous, then I don't see why it's necessary to bond the hot to the cold in the bathroom where a combi is concerned; they too are joined at the metal plate? I am a newbie though.
Hi John, in regards to supplementary bonding, what is the purpose of it? I understand it's to keep everything at the same potential. But if all extraneous pipes ect are bonded to the same MET as the electrical installation how can they be potentially different? Appologies if the question seems daft, I'm still learning. Thanks.
Rob, someone could have installed a section of plastic pipe or a plastic push-fit connector since the original bonding was installed. I have just found this in my 1974 house where the original bathroom was de-bonded due to plastic water pipes
totally agree John, however the definition of 'extraneous conductive part' is a common sense application not a rule book exam thing. So basically I agree with your analysis
I if you don’t have a wandering lead when you’re doing the earth bonding continuity test is it acceptable to conduct the test by probing onto say the earth terminal on the back of an electric cooker and then on the gas pipe to witch a gas cooker is connected ? , as all the earth conductors are connected to the earth bar in the CU this will still give you continuity, ? You could also probe onto the main water pipe into the boiler ? Would this be an acceptable way of conducting the test?
Yeah, the cpc's are very low resistance and are negligible against the values you are interested in. If pipework resistance to MET is >23k ohm then no need to bond, less than that then you do.
Curious.... our house it being rebuilt. No cables or earth are connected to the supply. I just did a resistance check between the pipes buried in the walls leading to rads and the main earth terminal in the meter box and I measured 44k ohms. Bonding needed? Obviously the whole place will be rcd protected
Superb instructional video John - very well put together and use of training resources. Couple of questions: how important is it to allow for inspection of the bonding after the work is completed? i.e. what happens if you make the bonds (to the central heating pipes) under the floorboards in the bathroom: is it essential that someone should be able to 'lift and inspect'? Also can you confirm that it is okay to make the bonds to the pipes at the bathroom door (from the landing) rather than from inside the bathroom itself - again this is due to inaccessibility post completion of the works (everything tiled over). Many thanks for a great job.
+BluesideUK Connections do need to be accessible for future inspection, so under the floorboards would not be acceptable. Connections can be done outside the bathroom such as in an adjacent cupboard, or in the loft space above, etc. Also consider that it often isn't necessary to connect to every pipe - if the hot and cold supplies are in metal throughout they may already be connected together via a mixer tap on the bath or basin, and although there are 2 pipes to a radiator, they are already connected via the radiator itself.
Thanks again! To clarify I have a radiator in my bathroom that is fed by two copper (central heating) pipes that enter from the landing and go under the bathroom door and then up into each leg of the radiator. I've just refurbished the bathroom ceramic tiling all walls and laminating tiling the floors - so re-access would involve 'breaking things'! All of the hot and water plumbing for bath and basin has been converted from copper to plastic, so only the radiator remains with copper pipes. If I need to bond the radiator to an earth (which is readily availble in the loft) then I'd rather avoid having the straps and wires visible hence why I was thinking about doing this either under the bathroom floorboards or at the point of entry on the landing.
Hi there I'm very new to this and was wondering what would be the concern of finding a repair to a water pipe in a bath room using a plastic connector id assume this would break the earthing circuit but if the rest was bonded correctly could this be in fact dangerous??
Not likely to be dangerous - if the bonding was connected before the plastic, then it just means that the rest of the pipes after are not bonded, but as they would be isolated from the others they would not then need bonding anyway. With bonding after the plastic part the piece before the plastic won't be bonded, but that would only be of concern if that section was accessible - if concealed such as under the bath then it would not be a problem. In newer installations, most bathrooms don't require bonding at all.
John Ward thank you for your reply it's very helpful ....I was wondering have you done any videos of how to decomission electrical appliances, components and associated wiring ??
Perhaps I'm missing something but why would we need to provide bonding between the pendant/light fitting and the shower, given that both these will have CPCs attached which lead back to the earth bar in the board, and are hence already connected? Thanks JW, one of the very best youtube electrical instructional channels, by far. I have learned a heck of a lot from your content, and been able to 'flesh out' a lot of what I've learned in the lvl 2 diploma and studying for my 18th edition exam
Hi folk can anyone give advice on this for me. My plumber replaced a radiator and used plastic pipe to do this. Should the plastic sections be bridged with earth cable?. Help required please.
Hi John. My house was wired in 1998, all wiring is the red and black . I have an electrical shower with a 10mm twin and earth supply new colours. installed in about 2011. All lighting circuits within the consumer unit are NOT on an RCD, where as the rest of the house is on RCD . Does this mean the I have to bond the shower to the Lighting circuit within the bathroom? and if so does it have to be a 10mm cable? The lights are within 3 meter high ceiling as it is a Victorian property. Thanks in advance.
@ M Kay. Hi I have the same problem. On the video at 28:51 there is a table of earth cable sizes, I saw mine being a 4 mm earth cable. (The most common size). Did you sort your problem?.
@@frank1847 I asked but got no answer... I have not done anything about it. I have a 10mm twin and earth for the shower so the actual shower is ok, just the lights are not bonded as per the video. The switch is a pull cord so i personally do not see the issue, Just thought I would ask... However there is no law to bring anything up to code but just wondered.
@@mkay6089 @M Kay, Hi again. I think the idea is to link the lights with the shower earth as per the video. But I agree with you with a pull cord there is no issue,
@@rayc1503 Hi, Thank you for the reply. Yes the shower is RCD protected as explained. All switches are pull cord ( Shower power and lights) Many thanks again.
Working out the resistance you said 1667 ohms if there is an rcd which is based on 50v divided by 30mA. When you did the calculation for a over current device you mentioned a 6amp circuit but then did the caluclation at 30A, why was that please? Also are you measuring back to the MET?
50 volts is the maximum acceptable voltage on exposed conductive parts before the device trips.Type B circuit breakers need at least 5x the rated current to trip within the required time, so 30A for a 6A circuit breaker.
As a homeowner I am still slightly unclear as to why it's necessary to link an earth conductor from the bathroom shower and light to waterpipes if the waterpipes are already bonded to earth elsewhere in the house such as at the entry stopcock. I would have thought that if any live conductor touched a waterpipe anywhere - including inside the shower - the current would run straight to earth. I know I'm missing something here..
Two things - bonding them at the location keeps the resistance between the various parts to the lowest possible value. Although copper pipes have a low resistance, it's not zero, so relying on bonding elsewhere would result in a higher resistance between the parts, and a higher voltage on them when a fault occurs. The other is that pipes elsewhere can be altered, cut, plastic joints installed, whole pipes replaced with plastic and so on by people unaware of the consequences of them being used as protective bonding.
Hi John can you please confirm me for existing installation if bonding to gas water pipes are less than 6mm, what code should I use for EICR certificate please, because you are the only great man I can make clear in my mind?
That would depend on the earthing arrangement. For TN-CS, yes it would need to be 10mm so 6mm would be undersized. However, 6mm could be perfectly adequate in a TN-S system and in some situations, even 2.5mm could be fine if it was TT.
I’m still yet to see a valid scenario where a shock could occur if a) the main bonding is in place and b) the CPC,s are connected together in the CU in a dwelling ?
Thanks very much JW. I have a couple of questions relating to extraneous conductive parts. Where the water supply pipe enters the building, is plastic and does not require bonding (as per 18th Ed changes,) there is not much guidance on this, but is it safe to say that omitting all bonding to the copper pipes is essential now because these water pipes are no longer extraneous? There's also loads of push fit fittings to copper pipes breaking the continuity of these pipes, so do they need bonding between also? Thanks in advance!
If items are not extraneous conductive parts they don't need bonding. Plastic isn't conductive, and pieces of copper pipe entirely within the building won't be introducing any potential, so neither require bonding, and never did.
@@jwflame Thank you for your advice, you have answered a very valuable question. I am now at ease. That's the trouble with being an electrician, the lack of information. We're so lucky to have people like you to educate us and thanks once again for reaching out.
Hi John, I worked in the era where you didn't need paper qualifications, and where everything including the cutlery was earthed. I've not worked in this field for 30 years, so equipotential bonding is fairly new to me. My interpretation was that all metalwork in the bathroom was bonded together, so it's all at the same potential with none of it being connected to the main in coming earth, but then you mention extraneous conductive parts. This is where I get confused as you mentioned extraneous parts when you were talking about the main bonding. So is any part of the equipotential bonding connected to the main earth bonding. My bathroom has everything bonded to the main bonding cable, even the bath. I was told that this was dangerous as there are to many paths to earth and that none of the E P bonding should be connected to anything else, but then the shower pipe is earthed to the light fitting which in turn goes back to the main earthing circuit. Please can you help.
+luckyglyn You have the concept correct - bonding together to keep items at the same potential. However it's not just because it's metal - it needs to be metal/conductive and capable of introducing a potential from outside the room. So water pipes, earthing wires from circuits supplying the room, heating pipes and cast iron waste pipes would be bonded as they enter from outside the room. Towel rails, radiators, toilet roll holders, door handles and a metal wall cabinet would not.as they are totally contained within the bathroom. Connecting to the main earthing for the building is not required as that is typically outside of the room and unrelated to keeping everything in the room at the same potential. However it will usually end up connected via the individual lighting circuits, shower circuit, etc.
So would it be advisable to disconnect any bonding cables in the bathroom that go back to the main earthing point, for safety reasons, and just leave the other cables in place. Thank you. Brilliant videos John.
This always baffles me as to how you would become live before touching one of these extraneous conductive parts in the first place!! Please, if somebody could give me an example of this would be amazing thank you.
Funny how much of the Electrical Regulations are based on folk law and old wives tales. 240V AC is run in domestic bathrooms to power sockets in Australia but are far too dangerous to run in the English equivalent. That said there is some money to be made from keeping the "stories" alive. Thanks for explaining.
+John Ward So in other words not like the regulations for accessible exposed parts where there are diagrams of exactly how many cm in various directions are considered accessible (think overhead power lines, big electrical rooms etc.)
You have strange rules in uk. Ok. This video was the first time I heard of such a thing as an electric shower. Here in Finland, the shower will always have hot and cold water and the water temperature is adjusted by the mixer valve. The hot water is distributed throughout the house from one boiler. In Finnish building, water pipes and boiler (boiler is usually electric, geothermal, oil burner or wood chip burner but never gas) must be grounded. Normally it is done at the boiler where branches the hot and cold pipes, the same way as your photo that was pointless. ;) However, nowadays metal pipes are no longer used in residential buildings or perhaps in the heat distribution rooms. Other required items to be separately grounded are, ventilation pipes, concrete Reinforcing bars, metal cable routes and TV-antenna. All equipotential bonding is carried out via the grounding and every new house have ground electrode, three phases and separate PE and N, 230/400V. Older houses have three phases and PEN, otherwise the same.
The main reason for electric showers in the UK is that most dwellings have a cold water storage tank in the roof, and this pressurises the whole system for domestic hot and cold water. This means that the water pressure in upstairs bathrooms may be too low to provide a sufficient rapid flow of water in a shower. However, an electric shower connected directly to the incoming water supply of the house will have a much higher water pressure and so be more effective in operation. From what you say, I would guess that the water system in Finnish dwellings is pressurised to mains pressure and that there is no cold water storage tank - or at least not one that is vented to the atmosphere. One other solution in the UK is to have a shower pump to raise the water pressure. The pump operates automatically when the mixer valve is turned on. It has two low pressure feeds of hot and cold water.
This is a good video but does contain some contradictions. Could someone please answer the following: 1. Does the supplementary bonding conductor have to be a single continuous conductor; like when a Main Bonding conductor is used for both gas and water? 2. 6:50 why bond Class II equipment as surely they are not exposed because their external surface is not metallic/ they are double insulated? 3. 11:00 How is it possible to terminate a 4mm2 conductor in a light, which has terminations designed for 1.5 mm2 conductors? 4. 15:12 why does the bath metal waste pipe need supplementary bonding - surely it would require Main Bonding as it is extraneous to the building? 5. Shower and light joined with supplementary bonding - do you also have to join to the light switch? Shaver socket? Extractor fan? etc. 15:55 and 31:00 Why don’t you include to the electric towel rail? 6. What instrument do you use to measure up to 1,667 Ohms? Most low resistance ohm meters only measure up to 99.9 Ohms.
Whether you're legally are allowed to or not, It seems inadvisable, having the first notice of a fault being a shock is not good practice. Then there's the edge cases with a break to the neutral, or a neutral fault in one area combined with a live fault in another where an RCD wouldn't save you, and it's still absolutely needed
@@AngDavies I cant see any extra bonding to the gas pipe or incoming water.....all the pipes under the boiler are earth to each other but not to anything else, it seems.......time for an electrician?
@@tobybarker6808 the bonding should be at the isolation valve to the building (stopcock), not at the boiler itself if I understand JW correctly, so check that first if you know where it is?(also to verify it's not plastic)
@@tobybarker6808 pipes with no continuous electrical path back to the pipe in the ground are not dangerous (i.e., if there is a break caused by an elbow, it doesn't matter) Only things that are earthed through some path other than the main protective conductor at the consumer unit need bonding (i.e they're electrically connected to something buried In The ground) If they're just disconnected pieces of metal they don't need ( and shouldn't have) an earth wire, unless they're at risk of becoming live through contact with mains circuitry. Any pipes downstream of a plastic elbow/pipe, wouldn't need bonding, even if metal, unless they then went underground again, because the elbow/pipe broke the secondary path to earth, and thus danger. Tldr: bonding is not to earth something, it is to prevent something that is *already* earthed through other means from being dangerous, if that secondary connection to earth is broken, the need for bonding is lost
All electric circuits will have their earths connected at the fuse box so why would a bathroom light need to be earth bonded to a shower? .......... presumably to cater for risk of a loose earth wire?
The concept to to keep all of the conductive parts at the same potential by connecting them together within the room. Although they may be connected together at the fuse box / consumer unit, that may be a significant distance away, and the resistance of the wiring could result in voltage differences between the various parts. The further away the connections are, the more likely it is that the voltage on those parts will be different.
No, as the chassis of the boilers have an integral equpotential point. As long as the gas and water pipes are bonded with 10 mm² wire. Under the 18th edition if you have m.d.p.e pipe (plastic) downstream of the water stopcock or gas meter bonding isn't required. This would only be the case if all circuits at the consumer unit RCD protected.
The RCD requirement is regarding the ommision of supplementary bonding conductors, it is nothing to do with main protective bonding conductors. If your service pipework is extraneous, bond it, if it is not, don't.
Amazing how things change or shall I say the theory , I was taught that mechanical joints are not electrical joints hence the equipotential bonding . Ask the plumber to make all his pipe joints soldered 🤣
I just had a EIC report telling me that the water and gas pipes need bonding, just as John points out is completely pointless as they all go into a chunk of metal called the gas boiler.
Yeah, any extraneous service pupewoek would need to be bonded. You can't just rely on the cpc of the boiler as a main protecrtive bonding conductor as it will almost certainly be undersized and in the wrong position to meet the regulation for bonding service pipework.
I think a lot of boiler installers provide the links to cover their ass. It's cheap insurance for them. They can show they provided the links but if the electrician actually used them isn't their problem.
