Steel Bath how to earth.

[bernardgreen]

If you agree with the new regs that an RCD with a possible failure rate of 7% mitigates omitting supplementary bonding than you might decide not to do it

The RCD will not protect against a shock to a person touching true ground and something connected or bonded to the "earth" CPC when the CPC derived from the neutral goes above true ground potential due to a network neutral failure / fault.

So if a 7% failure rate of RCD's is "permitted" then the far lower risk of a bouncing neutral can also be accepted by the regulations. Not much consolation for the person injured by that once before death occurance.

 

[homemaker]

Yeah the unmarked one is for the shower.

so shall i use the bolt and nut and earth it to the hot and cold pipes.

 

[JohnW2]

If you agree with the new regs that an RCD with a possible failure rate of 7% mitigates omitting supplementary bonding than you might decide not to do it

It seems to me that the most important condition for the ommission of supplementary bonding in bathrooms is that given in 701.415.2(vi) - i.e. the requirement that all extraneous-conductive-parts are effectively connected to the the MPB. What that is saying, amongst other things, is that if all the e-c-ps are effectively bonded together anyway, they do not need extra bts of local G/Y to bond them together.

Although 701.415.2(v) does, indeed, state that RCD protection is also needed in order to allow supplementary bonding to be omitted,I'm not entirely sure that I really understand the thinking behind that. I'm certainly not denying that RCD protection is a good idea for a bathroom, but I'm not sure why its absence should cause one to have to locally bond e-p-cs which are already (as required by 701.415.2(vi) effectively bonded together. Perhaps I'm missing something.

Kind Regards, John

 

[EFLImpudence]

It seems to me that the most important condition for the ommission of supplementary bonding in bathrooms is that given in 701.415.2(vi) - i.e. the requirement that all extraneous-conductive-parts are effectively connected to the the MPB. What that is saying, amongst other things, is that if all the e-c-ps are effectively bonded together anyway, they do not need extra bts of local G/Y to bond them together.

Yes. Does that not mean that supplementary bonding is not necessary when the e-c-ps are already bonded - i.e. by bonding elsewhere.

Although 701.415.2(v) does, indeed, state that RCD protection is also needed in order to allow supplementary bonding to be omitted,I'm not entirely sure that I really understand the thinking behind that. I'm certainly not denying that RCD protection is a good idea for a bathroom, but I'm not sure why its absence should cause one to have to locally bond e-p-cs which are already (as required by 701.415.2(vi) effectively bonded together. Perhaps I'm missing something.

This surely means that without RCDs bonding may be needed - if above conditions are not met - but with an RCD it may be omitted - even if above conditions are not met.

 

[EFLImpudence]

The RCD will not protect against a shock to a person touching true ground and something connected or bonded to the "earth" CPC when the CPC derived from the neutral goes above true ground potential due to a network neutral failure / fault.

Do you mean by this that the RCD will not operate, i.e. disconnect supply?

 

[ban-all-sheds]

so shall i use the bolt and nut and earth it to the hot and cold pipes.

Dunno - is the bath an extraneous-conductive-part or not?

BTW - it's bonding, not earthing.

 

[JohnW2]

Yes. Does that not mean that supplementary bonding is not necessary when the e-c-ps are already bonded - i.e. by bonding elsewhere.

Exactly. 701.415.2(vi) appears to be saying that if all the e-p-cs are already adequately connected together (electrically), they don't need to be additionally connected together locally (by 'supplementary bonding') - which seems to me to be little more than a statement of the obvious, for any location.

This surely means that without RCDs bonding may be needed - if above conditions are not met - but with an RCD it may be omitted - even if above conditions are not met.

No - and that's my point. 701.415.2 says that supplementary bonding can anly be omitted only if all three of 701.415.2(iv), 701.415.2(v) and 701.415.2(vi) are satisfied. In other words, if there is no RCD protection (i.e.701.415.2(v) not satisfied), then you have to have supplementary bonding even if all the e-p-cs present are already adequately connected together (electrically). That is what I was suggesting appears very illogical - do you agree?

Kind Regards, John.

 

[JohnW2]

Dunno - is the bath an extraneous-conductive-part or not?
BTW - it's bonding, not earthing.

That's an interesting one. It probably isn't an e-c-p, and therefore probably doesn't need bonding. However, if (as has been suggested by some in other threads), the main purpose of connecting a G/Y to the bath would be to cause an RCD to operate should a source of electricity touch the bath, then I think that would mean that the purpose of the G/Y was earthing, not bonding, wouldn't it?

Kind Regards, John.

 

[ban-all-sheds]

Here we go again.

 

[matt1e]

Here we go again.

you took the words out off my mouth

 

[JohnW2]

Here we go again.

you took the words out off my mouth

It weren't me that started it m'lud - it was BAS who wrote "it's bonding, not earthing"

Kind Regards, John.

 

[Paul_C]

The RCD will not protect against a shock to a person touching true ground and something connected or bonded to the "earth" CPC when the CPC derived from the neutral goes above true ground potential due to a network neutral failure / fault.

Do you mean by this that the RCD will not operate, i.e. disconnect supply?

How could it? In the scenario Bernard outlined the current which is resulting in a shock is not passing through the RCD, and even if you opened that RCD manually, it would not remove the potential (relative to true earth) on the supply neutral. You could turn off the whole installation at the main switch and it still wouldn't prevent the shock.

 

[Paul_C]

It weren't me that started it m'lud - it was BAS who wrote "it's bonding, not earthing"

Quiz time: Where would you find this phrase?

The extraneous fixed metalwork required to be bonded and earthed in these circumstances includes the following:

(i) Baths and exposed metal pipes, radiators, sinks and tanks, in the absence of metal-to-metal joints of negligible electrical resistance.

 

[EFLImpudence]

The RCD will not protect against a shock to a person touching true ground and something connected or bonded to the "earth" CPC when the CPC derived from the neutral goes above true ground potential due to a network neutral failure / fault.

Do you mean by this that the RCD will not operate, i.e. disconnect supply?

How could it? In the scenario Bernard outlined the current which is resulting in a shock is not passing through the RCD, and even if you opened that RCD manually, it would not remove the potential (relative to true earth) on the supply neutral. You could turn off the whole installation at the main switch and it still wouldn't prevent the shock.

Sorry, I didn't read it carefully enough - I didn't realise there were no lives involved.

 

[EFLImpudence]

so shall i use the bolt and nut and earth it to the hot and cold pipes.

The first reply to your question cannot be improved.