Cable Calc.

[scotsparky]

will double check it all still abit rough from last night when i did it

 

[Mark.W]

Or you could get him to move his house closer to the office

 

[saveloy]

The way I have always done it is to calculate the VD & CCC for the cable up to the office with a design current of 40A. I would then design the circuits in the office seperately so 3% for lighting and 5% for power. Hope that makes sense?

Thats exactly the way I do it. So would you agree with my calcs below as it appears that on the supply cable only there is already a VD of 11.2vd. I understand that part of the VD is a result of the lighting circuit draw (6A??) and that its quite posiible that the total current draw will probably not exceed say 32 A. But it just seems quite high! Am I missing something really obvious?

Design Current 40A. Length of run 100m.
16mm SWA

VD= (2.8 x 40A x 100m) = 11.2V to Submain

5% Vd for power 5% x 230v = 11.5v
3% for lighting 3% x 230 = 6.9v

 

[Mark.W]

Yeah that looks ok mate!