Bond sinks and mains water with plastic at start

[Sadsyndrome]

Hi sorry very long one. Please hop to bottom paragraph for short version. I’m just about to refurb bathroom in my 1986 house but bonding always confused me and I am still confused now! So my main incoming water pipe (extraneous) is Currently bonded To MET in 10mm and hot and cold pipes cross bonded near to main bond clamp. My gas pipe is also bonded to MET with 10mm. A stainless steel sink in small utility room is bonded ( I did that over 20 years ago) with the copper pipes as it has with plastic between pipes and sink. The bathroom has a shaver socket and Water based radiator with copper pipes, I see no signs of supplementary bonding.

i think bonding sinks is a very old requirement and I also believe water main with plastic incoming pipe no longer requires bonding.

But if the sink and main water is not bonded and there are plastic pipes section in and around the plumbing system what would happen if a fault condition eg cable touching copper pipe or sink occurred? The house is 1986 and all circuits protected by a single RCD 30ma but if the sink and some of the main Copper pipework is not earthed I guess the rcd wouldn’t detect leakage and would sit at mains voltage? Is that right? Only when someone came along and touched the pipe or sink would rcd hopefully trip (they can go wrong themselves).

I guess what I am asking is there a good reason NOT to have Steel sink and main water incomer bonded to MET? I know it’s not stipulated by regs but in this case I can see a benefit of doing it. Also given the lack of electrical equipment in bathroom and the fact the rcd protects all circuits, is the lack of supplementary bonding there OK?

 

[cliffed]

Yea old school sparkies would bond the water but the requirement now like you said, if it’s a plastic entry into building it now does not require bonding.
Mixture of metal & plastic piping is irrelevant.
The answer I got of the Niceic is that any metalwork regarding those pipes will for fortuitously earthed elsewhere by boiler, Imm heater, washing machine etc.
It’s not a extraneous part & no bonding required.

 

[mattg4321]

No bonding required so long as all circuits in the bathroom are 30ma rcd protected.

If not then supplementary bonding is required.

 

[LastManOnline]

but bonding always confused me and I am still confused now!

You are not alone on that one?

 

[UNG]

Mixture of metal & plastic piping is irrelevant.
The answer I got of the Niceic is that any metalwork regarding those pipes will for fortuitously earthed elsewhere by boiler, Imm heater, washing machine etc.

Given a washing machine is connected to the water pipe with a rubber hose how do the NICEIC think the washing machine fortuitously earth's the copper pipework

 

[Sadsyndrome]

thx all. i understand there is no longer a requirement to bond kitchen sink or water pipe if plastic entering building. but if this metal is not now extraneous (outside building) AND not exposed conductive part of part of electrical installation iit can sit there unbonded and become live in fault condition? Does this mean no overcurrent device (mcb) would operate neither earth leakage ( rcd). ONLY when somone grounded that faulty live metalwork would the fuse/ mcb or rcd operate? we laughed back in day when 15th edition said to bond everything but this does seem rather odd! I will leave the sink bond in then BUT is there a reason (safety) why I shouldnt? i appreciate its not in regs.

 

[DPG]

thx all. i understand there is no longer a requirement to bond kitchen sink or water pipe if plastic entering building. but if this metal is not now extraneous (outside building) AND not exposed conductive part of part of electrical installation iit can sit there unbonded and become live in fault condition? Does this mean no overcurrent device (mcb) would operate neither earth leakage ( rcd). ONLY when somone grounded that faulty live metalwork would the fuse/ mcb or rcd operate? we laughed back in day when 15th edition said to bond everything but this does seem rather odd! I will leave the sink bond in then BUT is there a reason (safety) why I shouldnt? i appreciate its not in regs.

Part of the problem is that by bonding bits of random metalwork, you are connecting them to the electrical system. Now admittedly this should never be a problem, but dont forget that the installation earth is not always at 0v when there is a fault condition, and the voltage on these metal parts will rise.

 

[Sadsyndrome]

Good point. Damned if we do damned if we do the then! I guess my question is which is the more likely fault condition..an earth fault on main installation which raises its potential and that of any bonded metalwork OR a fault within the installation (e.g. pipe touched by cable) which raises significantly the potential of the various non-bonded metalwork In the building.

Guess it’s all academic on my installation as everything is protected by 30ma rcd anyway (assuming rcd doesn’t fail at same time as fault condition occurs which is less likely than me winning euro millions tomorrow)

 

[DPG]

Good point. Damned if we do damned if we do the then! I guess my question is which is the more likely fault condition..an earth fault on main installation which raises its potential and that of any bonded metalwork OR a fault within the installation (e.g. pipe touched by cable) which raises significantly the potential of the various non-bonded metalwork In the building.

Guess it’s all academic on my installation as everything is protected by 30ma rcd anyway (assuming rcd doesn’t fail at same time as fault condition occurs which is less likely than me winning euro millions tomorrow)

I'd mention that faulty RCDs are not uncommon, but I wouldn't want to worry you ?

I gurss the important thing is to keep your electrical system safe and have it checked periodically. Also dont forget to test RCDs with the button every now and again.

 

[Sadsyndrome]

? I used to it all my own electrical work given I was a time served sparky once upon a time (mainly industrial though). I need to change cu now to increase number of RCD, I only have one at the moment, maybe add RCBOs and add a new circuit to shed. I was thinking of buying MFT but at £500 for a cheaper one and the fact that even after doing the job properly and testing it, it still doesn’t comply with building regs because I’m not certified means I’ve got to pay someone. Council want £477just to test! Thing is that these regs are here to improve safety but in reality how many people will just bung it in to save money. It does rankle a bit to think that I did 4-5 years of training/ studying and can’t legally change a cu myself without paying a lot to someone to test it! I wonder if I accidentally smashed the plastic cu enclosure with a hammer if I could legally change it as an emergency procedure??

 

[stevethesparks]

The more honest you are, the more likely to get caught. Nice to see the sheds still selling cheap CU's for the public to replace themselves. Does my nut in.

 

[Pete999]

Hi sorry very long one. Please hop to bottom paragraph for short version. I’m just about to refurb bathroom in my 1986 house but bonding always confused me and I am still confused now! So my main incoming water pipe (extraneous) is Currently bonded To MET in 10mm and hot and cold pipes cross bonded near to main bond clamp. My gas pipe is also bonded to MET with 10mm. A stainless steel sink in small utility room is bonded ( I did that over 20 years ago) with the copper pipes as it has with plastic between pipes and sink. The bathroom has a shaver socket and Water based radiator with copper pipes, I see no signs of supplementary bonding.

i think bonding sinks is a very old requirement and I also believe water main with plastic incoming pipe no longer requires bonding.

But if the sink and main water is not bonded and there are plastic pipes section in and around the plumbing system what would happen if a fault condition eg cable touching copper pipe or sink occurred? The house is 1986 and all circuits protected by a single RCD 30ma but if the sink and some of the main Copper pipework is not earthed I guess the rcd wouldn’t detect leakage and would sit at mains voltage? Is that right? Only when someone came along and touched the pipe or sink would rcd hopefully trip (they can go wrong themselves).

I guess what I am asking is there a good reason NOT to have Steel sink and main water incomer bonded to MET? I know it’s not stipulated by regs but in this case I can see a benefit of doing it. Also given the lack of electrical equipment in bathroom and the fact the rcd protects all circuits, is the lack of supplementary bonding there OK?

Have you tested the sink to see if it requires bonding?
'

 

[DPG]

Have you tested the sink to see if it requires bonding?
'

He does say the pipes are plastic to the sink, but fair point.

 

[Sadsyndrome]

He does say the pipes are plastic to the sink, but fair point.

I thought the regulation states kitchen sinks don’t require bonding? would a test be useful because things may well change in future especially with introduction of plastic pipe into copper pipe systems.

 

[DPG]

I thought the regulation states kitchen sinks don’t require bonding? would a test be useful because things may well change in future especially with introduction of plastic pipe into copper pipe systems.

They don't specifically need bonding. But any extraneous metal parts may need bonding. The sink is unlikely to be an extraneous conductive part.