What cable size

[dma.electrical]

I have a 25m run with the cable being clipped to a wall. it will be an swa. the md is 83.04A. i'm having a brain meltdown day and in need of a little reminder of how to do this. my brain is telling me 16mm 3c swa would be fine.

 

[wallyanker]

Haven't got my books with me i think:

Pick a size cable that is just above max demand, then apply any de-rating factors, eg, grouping, temp, etc.

mv/a/m x length x Ib then divide 1000 (this is for volt drop)

Make sure you protective device is suitably rated to protect the cable.

Hope this helps

 

[Guest123]

The thing to remember is whilst the VD of the sub-main may be within limits, the outgoing circuits from the new sub-board may not be.

Take into account total VD from the origin to the end of any final circuits supplied form the new sub-board.