SWA cables

[martynb01132]

Hi all looking for help on this one, if Im running SWA cables what is the minimum line size before I have to run a seprate earth, cheers Martyn

 

[Darkwood]

Its not as straight forward as giving a simple answer as it depends on cores as well as size meaning it dosnt follow a predictable path, im sure someone else can point you to the relevent table as i havent got it to hand.

 

[martynb01132]

Cheers I working for a company who insist we dont need to run a separate earth on any swa cable from 10mm upwards I think we do, generally the voltage is 400v 3 line supplies.

 

[Darkwood]

Cheers I working for a company who insist we dont need to run a separate earth on any swa cable from 10mm upwards I think we do, generally the voltage is 400v 3 line supplies.

i would question the kind of company you work for as they are clearly wrong in saying this you can work it out from the calculations in the regs as as i said before its size and core dependant but as you get to the larger swa cables then it becomes a requirement all the time im sure someone else will direct you to the table i spoke of.
Are you sure they didnt say 10mm or less?

 

[martynb01132]

No I seen them put in 240s with no separte earths

 

[andekoch]

the answer is in one of the NICEIC newsletters that are available from their site, I cant remember off hand but I think it was ok to use the armour as the CPC for line less than 6mm. Check the article though

 

[sparks1234]

the answer is in one of the NICEIC newsletters that are available from their site, I cant remember off hand but I think it was ok to use the armour as the CPC for line less than 6mm. Check the article though

You can go a lot higher than that, just trying to find it on the web and if find it i will post it

Found it

steel wire armour as the earth conductor | GadSolutions,Electrical services,testing and excellence.

 

[martynb01132]

Thanks for your help

 

[quince80]

i've seen some meaty swa's pulled in without a cpc to a point that i have had to question my own contractor manager whether a additional cpc should be pulled in. what he told me was they use the 'amtec' programme for the cable calc's. this could be used as a legal document if it ever went that far.

 

[andyb]

You can go a lot higher than that, just trying to find it on the web and if find it i will post it

Found it

steel wire armour as the earth conductor | GadSolutions,Electrical services,testing and excellence.

I think the csa of this tables refers to the steel, the copper equivilent is much smaller but can still be used.

From memory 70'C cable you are allright up to about 150 3 core and 400 4 core.

90'C cable is a bit more tricky, with 4 core ok up to 70mm but 3&2 core not so straight forward.

I will try and find something to post.

Try this from earthingnuts

http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf