Undersize CPC

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binky

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Hi all, have just been doing PIR on old property where CPC in 2.5mm FTE is 1mm. 2 issues arise from this:-

1/ what fault code is appropriate (if any)

2/ does circuit need re-wiring? I seem to re-call having read an article about this somewhere but can't find it, so any assisstance greatly appreciated.

 

M107

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Well I seem to remember reading something along the lines of if the ocpd is a 3036, the circuit shouldn't be extended or the 1mm cpc used (so in effect a rewire).

I'd code it as 2 (requires improvement)

 

hamlettphil

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at work we rewire in these cases, i know it could be a lot different in contactor world, ie the people not wanting to pay for a rewire.

 

cheggers

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I would code 2 this if it was a 30amp 3036. you could down rate to 20amp 3036 and this would comply or a 32A mcb and this would comply. Does not require rewire unless you are short of work .LOL

 

The Godfather

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Code 4

But consider 434-03-03.

I might also add, there is a reference to the 1mm cable at the rear of the Part P document, with considerations to some of the afore mentioned issues.

Possible upgrading of Fuseboard or rewire (Consider 434-03-03)

Don

 

binky

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I would code 2 this if it was a 30amp 3036. you could down rate to 20amp 3036 and this would comply or a 32A mcb and this would comply. Does not require rewire unless you are short of work .LOL
:^O , not short of work, and don't fancy re-wire - 3 storeys, lots of junk, occupied:( :( .

Anyway, have found reference in handbook stating that 1mm is not suitable for 30A ring main protected by re-wirable fuse, due to potential thermal effects during fault conditions. Being ever helpful NICEIC doesn't suggest what is a suitable remedy, but I'm planning to fuse down to 20A or 16A MCB with RCD protection which should reduce responce times to faults and provide additional protection (PIR is preliminary to changing CU). Zs readings on circuits were pretty low so should be no foreseable problems.

Thanks for the replies :)

 

binky

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at work we rewire in these cases, i know it could be a lot different in contactor world, ie the people not wanting to pay for a rewire.
I would re-wire by choice but I'm short on time, and off on holiday soon, apart from the money aspect.

Maybe that's why I'm poor:_|

 

binky

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Just as a check I telephoned NICEIC today, and downsizing to 20A MCB is prefectly acceptable. Man on phone also says Type S RCDs for TT systems no longer required if fitting 17th board with twin 30Ma RCDs, given usual provisos like meter tails not buried etc as per new regs

 

extension15

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Mmm......

Just my thoughts, but:

A good Zs (from all outlets)?

And correct size fuse/mcb fitted (and bonding in place)...

:p

 

extension15

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Evenin` all.Would concur, ext. :D As long as all else is ok and within readings, I`d be code 4. (As GF also suggested!)
Evening KME..

I've marked this down as Code 4 many a inspection..

:D

 
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