earthing SWA cables

[cashnotakite]

quick question

i'm testing a board where there are 6 swa sub mains cables feeding dis boards. They are only 2 core so the armoured has been used as the earth.
for additional protection the banjos of the 6 SWA's has been linked out with one 6mm earth and taken to the boards earth bar.

does each SWA need its own earth and also the SWA's are 16mm so is a 6mm earth big enough?

is there anywhere in the regs or OSG where this is?

thanks in advance

 

[daniel hill]

i think of the top of my head it should be just more than half the size of the main conductor so should prob be 10mm mate

 

[Spudnik]

Is the db metalclad?

 

[havoone]

if the DBs are metal clad you should be able to use the swa of the cables as protective conductor providing they comply with Table 54.7, k1/k2x S.

 

[Mr. Mohammed]

technically the smallest earth conductor allowed is half the size of the supply conductor(s).

 

[mogga]

linkings ok but IMO each swa should have its own flying lead

 

[Risteard]

If it complies with the adiabatic equation then what's the problem? Cpcs don't have to be selected from the table.

But I would have thought a flylead should be taken from each cable.

 

[cashnotakite]

thanks very much everyone who gave me feedback on this

 

[RJS Contracts]

I was told by the NICEIC the other day that anything bigger than 10mm swa will need a seperate cpc. You cannot use the steel wire!!!

 

[mogga]

theres a table on forum somewhere Ill try n find it shows what swa armours require seperate earth

http://www.earthingnuts.co.uk/pdf/pvc_xlpe.pdf there you go RJS Your NICEIC man would probably be generalising