Cable Calc

[IAmSparkytus!]

Hello

Existing 69kva supply with the board 100m from the incoming supply (within a shopping centre).

Three phase board supplying lighting and power circuits.

Cable ran along a corridor on cable tray/ladder.

Online Cable calculators saying the run is OK for 25mm 4core but when I’ve used the BBB, it’s coming out at over 3% VD.

anyone care to do their own calc for me and let me know what they come up with?

Thanks

 

[westward10]

Your volt drop must take into consideration the final circuits from the distribution board, a rule of thumb is 2% for the submain. I don't need to calculate to know it isn't big enough to comply assuming the protective device is 100A.

 

[IAmSparkytus!]

What figure are you getting? Yes all that’s fitted at the minute is an existing fuse board at the end of an 85m cable which is fed from the 100A fuses (not sure if 88s or 1361s if that matters?)

Additional 15m of cable to be added to get the new board where it needs to be

Switched fused isolator with more 100A fuses inside to be used to extend the cable.

 

[DefyG]

Just done a quick/rough calc on app I have on phone and it shows >4% at FL.
Do you need all the capacity available? If you can reduced it with (say 63A fuses) it might comply?