Using Cpc In 16Mm T&e As Well As Separate 10Mm Earth.

[lyserman]

I am working on a 6 flat conversion which has a 3 phase supply so I am supplying two flats from each phase with a separate consumer unit for each flat.

The distribution for each flat is in 16mm T&E with a separate 10mm earth cable.

I was wondering is there anything intrinsically wrong in using the CPC from the T&E as well as the 10mm as the earth path?

It just seems a waste not to utilise the cpc.

Thanks,

Tony

 

[Evans Electric]

If I remember rightly the earth in a 16mm T/E  is OK  for a 60A HRC supply  if you do the math ( as they say in the US )

You'll get all the stuff about parallel paths now .

 

[SPECIAL LOCATION]

Using Cpc In 16Mm T&e As Well As Separate 10Mm Earth

Kerching will be the one to comment on this????

:innocent

 

[batty]

He's not allowed to anymore like Dave mentioning part p they have been banned.

If its PME does not have to be half the size of the neutral so 6mm wouldn't be large enough or am I talking rubbish again.

 

[m4tty]

I was under the impression that it shouldnt be left floating and needs to be tied down to earth. Could be talking rubbish tho

 

[batty]

You need to connect it both ends as well if you leave it disconnected and the cable gets damaged the CPC cannot function its a bit like leaving armouring disconnected on a SWA it has a function.

 

[Andy™]

only needs connected at both ends if its being used as a conductor. if it isnt, it only needs connected at supply end

 

[batty]

Agreed but it may as well function you can't  have to much CPC (ask Kerching)

 

[Andy™]

Agreed but it may as well function you can't  have to much CPC (ask Kerching)

yes. unless its to be made TT, but it isnt in this thread

 

[Sidewinder]

However, if it is to be used as a CPC, in parallel with another conductor, then EITHER, MUST be able to carry the full fault current at any point of their run.

 

[lyserman]

Thanks for the replies.

I agree the sums say that the cpc is large enough but as a distribution I was working on the 50% principal erring on the side of safety and it is TNS.

I was planning on connecting it at the supply end anyway so it could function as designed but could not find anything that precluded connection at both ends in conjunction with the 10mm.

Tony

 

[brman]

I am a bit confused. If it is TNS and the CPC meets the adiabatic then I don't see the problem. Why would you not connect it both ends like any other cpc?

Maybe I missunderstand the situation but you said these were distribution circuits, so we are talking about a cpc, not the main earthing conductor. (not that I think that would change the arguement on TNS) 

My question is why are you running a 10mm as well? I'd guess this is actually a bonding conductor so a different discussion to the cpc?

have I got the wrong end of the stick?

 

[batty]

Other thing is can you keep it all surface also otherwise an RCD may be required ?

 

[lyserman]

Excellent point Batty! The cable runs will be boxed in where they run up the walls. So I will be fitting 63A RCCBs as isolators for each flat.

The concensus from various sources seems to be each flat should be treated as a separate installation as far as bonding is concerned, hence the requirement for the 10mm earth.

The water and gas services into the property will be bonded to the MET with the landlord's supply and each flat will be bonded individually via the 10mm.

 

[batty]

If they are boxed in then RCD protection shouldn't be required as long as it obviously boxing in. Sometimes boxing in looks like part of a wall and to me this possibly would require RCD protection. Is RCCB time delay? 

 

[Sidewinder]

Remember that an RCCB has no over current protection

 

[batty]

What is an RCCB only ones I recognise are RCD and RCBO. Are they not an old version of RCD?

 

[Blue Duck]

That would be an elcb, rccb is just a different way... Craptree still call them Rccb's.

Oh and @op I would terminate the original CPC just in case someone decides to hang a picture on it.

 

[Evans Electric]

Residual Current Circuit Breaker   IIRC  Batts     Same thing really.

 

[Andy™]

What is an RCCB only ones I recognise are RCD and RCBO. Are they not an old version of RCD?

residul current circuit breaker. just a different name for an RCD