CPC not continuous on ring final circuit

[studentspark]

The CPC on a Kitchen RFC is not continuous.

It looks like some one has had a go at fixing it, by fusing it down to 20 A, and putting that circuit on an RCD. So I wonder if the break was not able to be located.

Each socket is earthed , via each leg. R2 readings are good, and Zs is good
Of course, the thing to do is look for the break and put right.

I will be returning to look for the fault, but I wonder how you would code it, and, if the break can't be found, Im wondering about the options.

Being a kitchen circuit, it is quite heavily loaded, so the fact that fusing its down to 20 A is not ideal.

Now in a EICR, I would say a broken CPC on a ring final is a C2.

But since it has been fused down to 20 amps, could you argue that it is two radials?
I know the Line and neutrals are still as a ring, but Im wondering, the load will be shared better if left connected.

I would think about separating them, on their own 20A MCB
However, there is no space to add another MCB so can't split the ring and put each leg its own 20A MCB. And earthing wise, its as it is now.

I would appreciated any thoughts

Thanks

 

[EFLImpudence]

I will be returning to look for the fault, but I wonder how you would code it, and, if the break can't be found, Im wondering about the options.
Being a kitchen circuit, it is quite heavily loaded, so the fact that fusing its down to 20 A is not ideal.

Maybe not ideal but electrically satisfactory.

Now in a EICR, I would say a broken CPC on a ring final is a C2.

It's not really a ring now as far as 433.1.204 is concerned.

But since it has been fused down to 20 amps, could you argue that it is two radials?
I know the Line and neutrals are still as a ring, but Im wondering, the load will be shared better if left connected.

You could argue that and you may as well leave it as it is.

I would think about separating them, on their own 20A MCB
However, there is no space to add another MCB so can't split the ring and put each leg its own 20A MCB. And earthing wise, its as it is now.

You can't then.

Locate the fault and see if it is practcal to repair it first.
It maybe just one disconnected conductor in a socket.

 

[flameport]

So I wonder if the break was not able to be located.

More likely that someone couldn't be bothered to locate it.

if the break can't be found,

It can be found, and either repaired, or if the fault is some piece of inaccessible cable that can't be replaced - L&N can be broken at that point instead, making it 2 radials.

there is no space to add another MCB

No other circuits that couldn't be combined?

 

[studentspark]

Not really any circuits to combine, its only a 6 way CU, and things are already doubled up

 

[JohnW2]

The CPC on a Kitchen RFC is not continuous. ..... Each socket is earthed , via each leg. ...

Do you mean that each socket has a path to earth (independently) via both 'legs' of the ring connected to it? If so, I son't quite see how the CPC ring cannot be continuous. Am I misunderstanding, or missing something?

Kind Regards, John

 

[John D v2.0]

It may not even need fusing down to 20a, if the loop impedence is low enough and the adiabatic passes it would be ok on a b32.

 

[Risteard]

It can't be satisfactory, even on a B20 circuit breaker, when there is clearly a fault and therefore it cannot be said with any confidence that an earth path will remain to all outlets. It is highly likely that there is simply fortuitous contact at present given the known fault.

 

[plugwash]

But since it has been fused down to 20 amps, could you argue that it is two radials?
I know the Line and neutrals are still as a ring, but Im wondering, the load will be shared better if left connected.

The load would indeed be better shared if left connected.

However IMO it is reckless to leave a circuit segment connected with an un-diagnosed fault. If the CPC is broken then there is a substantial chance that the other conductors in the cable are also compromised and/or that there is a loose wire flapping about that could easilly touch a live terminal.

So if the precise location of the fault cannot be located then IMO the only reasonable thing to do is to take the faulty segment out of service completely.

 

[John D v2.0]

If it was my house I'd find the fault and resolve it, but if testing finds its a valid circuit does that still make it non compliant by the regs? Or just bad workmanship?

 

[Risteard]

If it was my house I'd find the fault and resolve it, but if testing finds its a valid circuit does that still make it non compliant by the regs? Or just bad workmanship?

Not when there is a known fault. You can't possibly state with confidence that the cpc will remain in situ.

 

[John D v2.0]

Not when there is a known fault. You can't possibly state with confidence that the cpc will remain in situ.

I can't really say that 100% about any circuit, obviously it's more likely to have issues if you already are aware of an existing broken cpc, but without a copy of the regs in front of me i would find it hard to confirm what you are saying. Other than the workmanship reg.

 

[Risteard]

I can't really say that 100% about any circuit, obviously it's more likely to have issues if you already are aware of an existing broken cpc, but without a copy of the regs in front of me i would find it hard to confirm what you are saying. Other than the workmanship reg.

I really don't see how you could promote the use of a circuit with a known fault.

 

[John D v2.0]

the regs

the regs

I really don't see how you could promote the use of a circuit with a known fault.

As you can easily see, I'm not. I'm clearly asking a specific question about the regs, if you don't know the answer you can just say so

 

[sparkwright]

The obvious thing to do is try to find the fault, and inspect the wiring at all accessible connection points.

If it becomes apparent that a cable is damaged, and that cable can't be replaced practically, then that entire cable could be fully disconnected, and made into two radial circuits, either on one or two fuses/MCBs.

This would be fully acceptable.

You were concerned about a kitchen being on a 20 amp circuit, but you may be able to split it onto two 20 amp circuits.

You may be able to consider using a 25 amp MCB, though I'm not sure if this is recognised as being a standard circuit in such things as the On-Site Guide. (This is NOT intended to develop into a tirade about the regs and the OSG.)

 

[JohnW2]

You may be able to consider using a 25 amp MCB, though I'm not sure if this is recognised as being a standard circuit in such things as the On-Site Guide. (This is NOT intended to develop into a tirade about the regs and the OSG.)

If a circuit complies with all the relevant regs in BS7671, then it's surely fine - regardless of whether or not some other source recognises it a a "standard circuit" (which, unless I've missed it, is not a phrase or concept which exists in BS7671)?

Kind Regards, John