Reduced csa of cpc in T&E

[dook]

Evening all,

Sorry to bother you guys with possibly a very simple question but something I've never been clear on is why the csa of the cpc in twin and earth is smaller.

I've just started my electrical career and my fellow colleagues argued over the reasoning when I asked them!

Any info to help me understand this more would be gratefully appreciated.

Also, does any body run a reduced cpc csa when running circuits in singles?

Cheers!

 

[Risteard]

Cost...

 

[telectrix]

hmm, got me thinking. i can't think of any reason except that it's purely a manufacturing issue, as with the reduced csa of the cpc, it allows the outer sheath to partially wrap round the Line & Neutral. As for singles asfar as I know we all use same size cpc because we can

 

[johnboy6083]

when running in larger cables for submains, it is common to run reduced CSA CPC then too. I see it all the time in industrial and commercial jobs

 

[beaver74]

it is becouse the earth conductor if calculated properly will not have accessive current flowing through for long it so can be a smaller csa and also the cost also has it place here

 

[Adam W]

Basically it doesn't need to be the same size as the live conductors, so it isn't. Again, to save wonga.

S = √I²t÷k

 

[telectrix]

thought it was made smaller so it snapped when you stripped it and your cutters hit you in the face

 

[danzor]

thought it was made smaller so it snapped when you stripped it and your cutters hit you in the face

Ah still have my scar from this!

 

[Guest123]

Ah still have my scar from this!

I was thinking the same thing........above my right eyebrow.

 

[telectrix]

tried to strip nwith a stanley knife once, slashed my wrist. when will they realise us sparkys should not be let loose with sharp things

 

[dook]

thanks to all you guys for your responses! Scratching the newly painted wall with my cutters is a favourite of mine when it snaps!

 

[sparkylad]

Basically it doesn't need to be the same size as the live conductors, so it isn't. Again, to save wonga.

S = √I²t÷k

Adiabatic.

I agree with N S on this one


sparkylad

 

[Risteard]

thought it was made smaller so it snapped when you stripped it and your cutters hit you in the face

When I was an Apprentice I ended up with a pair of snips in my eye over this. Fortunately after a few hours in Casualty there was no permanent damage...

 

[High Tower]

hmm, got me thinking. i can't think of any reason except that it's purely a manufacturing issue, as with the reduced csa of the cpc, it allows the outer sheath to partially wrap round the Line & Neutral. As for singles asfar as I know we all use same size cpc because we can

Up to a certain CSS yes or 2.5mm however when installing 75mm swa we don't use 75mm cpc unless a core is used

 

[ezzzekiel]

mine was trimming resting on my leg when stanley decided to follow his own route