Conduit cabling sizes

[cliffed]

Helping out a fellow spark, 2nd fixing,nice school extension.
Have the regs changed,concerning cpc sizes with cables.
It’s all been specificed by consultant,the circuits are radials,which is a good thing.
Bit confused about the sizing of the cpc,obviously single cabling,4.0mm live & neutral,the strange thing is that the cpc is 2.5mm.
I always thought this should be 4.0mm,it this situation.

 

[Pete999]

Helping out a fellow spark, 2nd fixing,nice school extension.
Have the regs changed,concerning cpc sizes with cables.
It’s all been specificed by consultant,the circuits are radials,which is a good thing.
Bit confused about the sizing of the cpc,obviously single cabling,4.0mm live & neutral,the strange thing is that the cpc is 2.5mm.
I always thought this should be 4.0mm,it this situation.

Ant?

 

[Ian1981]

Helping out a fellow spark, 2nd fixing,nice school extension.
Have the regs changed,concerning cpc sizes with cables.
It’s all been specificed by consultant,the circuits are radials,which is a good thing.
Bit confused about the sizing of the cpc,obviously single cabling,4.0mm live & neutral,the strange thing is that the cpc is 2.5mm.
I always thought this should be 4.0mm,it this situation.

A cpc can be calculated by regulation 543.1.3 or selected via table 54.7 543.1.4.
FYI I’ve been installing galv conduit containment and wiring in singles to a MOD armoury new build, in which the consultant has stipulated 4mm live conductors and 2.5mm cpc for the ring finals.
And I kid you not there’s 2 sockets on each ring, 8 ring circuits in total!
Just means a lot more 25 and 32mm galv conduit to bend and install

 

[cliffed]

Ant?

What?

 

[cliffed]

A cpc can be calculated by regulation 543.1.3 or selected via table 54.7 543.1.4.
FYI I’ve been installing galv conduit containment and wiring in singles to a MOD armoury new build, in which the consultant has stipulated 4mm live conductors and 2.5mm cpc for the ring finals.
And I kid you not there’s 2 sockets on each ring, 8 ring circuits in total!
Just means a lot more 25 and 32mm galv conduit to bend and install

Ok,in my day,the cpc should have been the same size as live.
T/e cable being a composite cable,allowing for the cpc to be reduced.

 

[Pete999]

What?

Sorry Anthonybragg works on a lot of Schools, was just wonder what his take on the question was/is, should have been more explicit sorry.

 

[cliffed]

Cheers

 

[westward10]

The fact it is a school is irrelevant.

 

[Strima]

If your using galv why are you running a separate CPC?

 

[Ian1981]

Ok,in my day,the cpc should have been the same size as live.
T/e cable being a composite cable,allowing for the cpc to be reduced.

Like I say there’s no regulation that says you must have a cpc the same size as the live conductors.

 

[Ian1981]

If your using galv why are you running a separate CPC?

Because it’s been specified by an outside consultant/designer

 

[Strima]

Because it’s been specified by an outside consultant/designer

I should have quoted the OP, sorry I'm being a knob...

As for the MOD, I know exactly what their 'consultants' are like.

 

[Ian1981]

I should have quoted the OP, sorry I'm being a knob...

As for the MOD, I know exactly what their 'consultants' are like.

Don’t worry I didn’t think your being anything.
The OP is in the same boat tho, it’s been specified by an outside consultant, they know all!!! Depending on what there computer software tells them anyway

 

[Toneyz]

Sorry Anthonybragg works on a lot of Schools, was just wonder what his take on the question was/is, should have been more explicit sorry.

A majority of our projects there is an electrical consultant who does the design mostly nowadays it is a basket with LSF T & E etc. with conduit drops down walls. When in the few cases it is all trunking and conduit with singles they usually use the cpc size of that of T & E. They obviously use a computer design programme to check.

 

[cliffed]

Ok ,in this day & age,never just relied on the conduit for earth,always installed a cpc.