I.T room

[ianmacd]

Nothing.

So either ring it in 2.5 t&e or conduit with 2.5 singles (with 4mm cpcs) radial or conduit with all 4mm radials?

 

[spinlondon]

If you used 2.5mm

 

[musicspark]

One of the anomolies of the Regs. I'm afraid. Probably be sorted next year with the amendment.

As I do not feel qualified to amend the regs myself, or indeed feel confident enough to come to a conclusion on what is clearly an ambiguous section, I would tend to err on the side of caution and use a 4mm single for the cpc

After all, why go to all the trouble of including 543.7 if 543.7.1.3(iii). is telling us to ignore the rest of 543.7

 

[spinlondon]

I think a lot of it comes down to cost.

Using singles, it might be cheaper to use a 4mm

 

[ianmacd]

If you used 2.5mm

 

[ianmacd]

If you used 2.5mm

 

[spinlondon]

I meant ring.

Yes I had assumed that.

 

[spinlondon]

Also doesn't the size of your proposed extra cpc depend on its installation method too?

Of course.

 

[ianmacd]

Of course.

So if you use a radial doesnt it there need to be 4mm if in conduit or 10mm if clipped direct?

 

[spinlondon]

So if you use a radial doesnt it there need to be 4mm if in conduit or 10mm if clipped direct?

Yes, if a single conductor is used.

 

[ianmacd]

OK then I do not understand what you said above then as when I suggested a 2.5mm ring you said it would need a 1.5mm seperate cpc. Why?

 

[spinlondon]

OK then I do not understand what you said above then as when I suggested a 2.5mm ring you said it would need a 1.5mm seperate cpc. Why?

Sorry, you're quite right it wouldn't require an extra CPC at all.

It's only on Radials that the extra CPC is required.

 

[musicspark]

according to 543.7.2.1(ii){c}

two radial circuits (same size conductors and CPC), each with it's own breaker (same size) with the CPCs connected togetherWet Fish

 

[ianmacd]

I.E. a broken ring for L & N

 

[musicspark]

well sort of; if each end of the ring had it's own 16a breaker

 

[ianmacd]

So a have-a-go diyers ring with a 16A at one and and in the 40A shower mcb the other wired in 1mm and 4mm?

 

[musicspark]

So a have-a-go diyers ring with a 16A at one and and in the 40A shower mcb the other wired in 1mm and 4mm?

well yes I agree, But it wasn't me what wrote the regs;\

 

[Andy™]

according to 543.7.2.1(ii){c}two radial circuits (same size conductors and CPC), each with it's own breaker (same size) with the CPCs connected togetherWet Fish

why exactly are people constantly saying you need a 4mm earth? if you actually read the regulation, you would see that a 4mm is only required on a single protective conductor (ii), and is only one of 5 ways to satisfy 543.7.1.3. there is nothing wrong with having a 2.5/1.5 T&E and an additional earth of 1.5mm from the end back to DB

 

[musicspark]

[quote name='Andy

 

[ianmacd]

[quote name='Andy