Earthing & Bonding - Part 3 : Supplementary Protective Equipotential Bonding

Part 3 covers supplementary equipotential bonding and the most common location it is required - bathrooms.

[ianprior]

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.

[GunnyRabbit]

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!!

[apartmentswales]

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

[basejumper]

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

[debbiepaton]

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

[mr.d]

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..

[shilks]

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.

[nlo]

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.

[PJB]

All of the video, are extremely good.  The explanations are easy to follow.

[jeremykemp]

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.

[ManUned]

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

[peto]

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.

[brianlopez]

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.

[davidmarsden]

Nice that you kept the hot to the Left on the bath and basin,

[Marco-mgtv]

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 ?

[BluesideUK]

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.

[lewisbrand]

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

[mkay]

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.

[hasanmaz]

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.

[jimslip]

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.