Lighting Circuit - Mixed CPC Sizes!

[shocksmith222]

Hi All,

I am a newbie to the forum so please be gentle!

Today I have come across a recently rewired house and I noticed that the installing sparky has indicated on the Install Certificate that the lighting circuit is T&E 2 core 1.5mm and CPC 1.5mm. However, I have noticed that in fact there appears to be several runs where T&E 2 core 1.5mm and CPC 1.0mm has been used instead.

From a testing point of view it is fine and Max Zs is well within the Regs guidelines. I am just wondering 2 things and despite checking my regs cant find any 100% answer.

1. For the certificate - should it actually have been issued stating the smaller T&E 2 core 1.5mm and CPC 1.0mm rather than as it is now T&E 2 core 1.5mm and CPC 1.5mm?

2a) Am I obliged to advise the client that the T&E 2 core 1.5mm and CPC 1.0mm should now be replaced with the same cable as used in the majority of the lighting circuit, that is T&E 2 core 1.5mm and CPC 1.5mm
OR
2b) Can I simply leave it as it is and just advise the client that there is a mix of CPC size on the lighting circuit. Afterall the safety disconnect of the circuit is fine anyway.

Thanks to all in advance for your views.

 

[Sintra]

Hi All,

I am a newbie to the forum so please be gentle!

Today I have come across a recently rewired house and I noticed that the installing sparky has indicated on the Install Certificate that the lighting circuit is T&E 2 core 1.5mm and CPC 1.5mm. However, I have noticed that in fact there appears to be several runs where T&E 2 core 1.5mm and CPC 1.0mm has been used instead.



From a testing point of view it is fine and Max Zs is well within the Regs guidelines. I am just wondering 2 things and despite checking my regs cant find any 100% answer.

1. For the certificate - should it actually have been issued stating the smaller T&E 2 core 1.5mm and CPC 1.0mm rather than as it is now T&E 2 core 1.5mm and CPC 1.5mm?

2a) Am I obliged to advise the client that the T&E 2 core 1.5mm and CPC 1.0mm should now be replaced with the same cable as used in the majority of the lighting circuit, that is T&E 2 core 1.5mm and CPC 1.5mm
OR
2b) Can I simply leave it as it is and just advise the client that there is a mix of CPC size on the lighting circuit. Afterall the safety disconnect of the circuit is fine anyway.

Thanks to all in advance for your views.

I didn't know that you could get 1.5mm T&E with a 1.5mm cpc I thought all 1.5mm T&E had a 1mm cpc.

 

[Risteard]

I didn't know that you could get 1.5mm T&E with a 1.5mm cpc I thought all 1.5mm T&E had a 1mm cpc.

Same here.

But in answer to the hypothetical question, I would list the smallest csa present for the cpc.

 

[brs73]

1.5 and then go for a pint and relax a bit .

 

[pennywise]

You can't get it go with the smaller Csa.

 

[MarcT]

As pennywise said, record the smallest value. it's quite common to see mixed conductor sizes. One common practice was to wire the circuit in 1.5 and use 1.0 f or the switch drops.

 

[jenkers]

Hi - I've got the same issue at the moment: I'm, doing a pvc conduit installation using 1.5mm single core cpc on the lighting circuits in conduit (no supplier could get me 1mm single core), however there are places where I am going over to 1.5mm/1mm twin & earth outside conduit, where it seems sensible to do so. Is this OK?
(First post! - whew)

 

[kingeri]

Hi - I've got the same issue at the moment: I'm, doing a pvc conduit installation using 1.5mm single core cpc on the lighting circuits in conduit (no supplier could get me 1mm single core), however there are places where I am going over to 1.5mm/1mm twin & earth outside conduit, where it seems sensible to do so. Is this OK?
(First post! - whew)

It's fine! Just record the smallest CSA on the cert, and you could also note the differing sizes too. If Zs are OK then what's the issue?