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

 

[Risteard]

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

Only if you use the Table. No reason why you can't calculate utilising the adiabatic equation and use reduced csa cpc.

 

[Spudnik]

Gotta love stripping T&E.

I use the cpc pull method, and yes, its generally the nearest wall that bears the brunt when it slips/snaps.

Anything 4mm and above gets the stanley.

 

[johnboy6083]

amything 4mm and above, i snip at the end between cores, and then pull cores apart by hand.

 

[nickblake]

did you know your more likely to cut yourself with a blunt knife than a sharp one , smacked my self in the nose and gave me a nose bleed once lol

 

[High Tower]

did you know your more likely to cut yourself with a blunt knife than a sharp one , smacked my self in the nose and gave me a nose bleed once lol

Not true, odds are you stand more chance of a cut with a sharp knife as it's less forgiving, however you are right in as much as a cut with a blunt knife does a he'll of a lot more damage

 

[martysparky]

amything 4mm and above, i snip at the end between cores, and then pull cores apart by hand.

Why not do this on smaller cable?

 

[johnboy6083]

coas its quicker to pull the CPC. I dont use side cutters, i use the ones above. I pinch the CPC with theflat bits of steel near the handles, so it doesnt slip, or cut the CPC

 

[Adam W]

I use pliers to pull the cpc - it grabs it but doesn't cut it so you don't smack yourself in the face unless the handles fall off.

 

[Des 56]

I was giving my brother a rollicking whilst he was stripping a 2.5mm in an airing cupboard
He wasn't concentrating so I believe I was responsible
Snap, bang, eye,cutters with small piece of cpc sticking out,ripped down his eye
He held his hand to the eye and when he took it away,for a very short moment I saw the damage as what appeared like a half cupfull of water streamed down his face,I mean half a cupfull,thats not exagerating
He lost the eye

The reason for the detail
Always direct the cutters away from you as you strip
A simple message,but vey important

How many of us can say that they havn't been whacked by the cutters stripping cable

 

[High Tower]

When pulling cpc to strip cable I always spread my arms and never towards me, so same motion as if you were using hedge shears

 

[Jon Bridges]

I use these

They work well on t&e and singles and saves punching yourself in the face.

 

[High Tower]

I use these

They work well on t&e and singles and saves punching yourself in the face.

Nah not for me!! far to sensible!! i much prefer the suspense and danger of wether or not im gunna give myself a slap

 

[Markc]

Three broken teeth for me. After 22 years I had got off lightly with nothing more than grazed knuckles then bang and I smack myself in the mouth with me cutters. Mouthful of teeth shards and and a gap where they used to be. Had to be in winter as well so when the cold air hit the now open nerves I nearly hit the ceiling. It only takes a moments laps of concentration. Still got some new ones fitted and haven't done it again.............as yet!

 

[Des 56]

Three broken teeth for me. After 22 years I had got off lightly with nothing more than grazed knuckles then bang and I smack myself in the mouth with me cutters. Mouthful of teeth shards and and a gap where they used to be. Had to be in winter as well so when the cold air hit the now open nerves I nearly hit the ceiling. It only takes a moments laps of concentration. Still got some new ones fitted and haven't done it again.............as yet!

What have you done ?
"mashed my melf miv my mutters",

 

[High Tower]

What have you done ?
"mashed my melf miv my mutters",

he he he