Cable calc for meter tails?!!

[ukpablo]

ok, need a lil help.

Cu approx 40 metres from meter.

in a block of flats.

total demand is 132A therefore after diversity

132A x 0.4 = 52.8 A (approx)

cable run in tray in cable duct in free air.

100A cutout fuse in place at mo. currently in 25mm armoured! is this enough?

lil rusty on this one as this is a sub main cable so is there a difference?

 

[Johno]

I know this isn't the technical answer you wanted, but I would say 25mm2 (as 40m run) armoured on 63A fuse/MCB would be enough for any flat I have ever been to.

As for diversity, I think there is more common sense than calculations required.

I have just read the post again and am unsure of the situation.

How is it 132A x 0.4 because as far as I know there is no set rule for diveristy like that, it works like 100% of 1st shower and then 30% after, and 100% of socket circuit and then 10% after, etc

 

[ukpablo]

this is just a quick way for rule of thumb by multiplying by 0.4 for domestic.

 

[telectrix]

don't think current load is a problem. be more concerned with calculating volt drop

 

[morph]

3.5 v VD
does that sound right ?

based on 52.8 A

 

[KINKY]

3.5 v VD
does that sound right ?

based on 52.8 A

It will not be that high.

Sounds ok to me 25mm.

If you can wait till tomo i shall get the Amtech out and do a calc for you.

 

[morph]

i used 1.2 multiplying factor as one should

40x52x(0.72+0.72)x1.2 / 1000 = 3.6 volts

but i would be interested in the calc provided by your software
thanks

 

[J@mes]

I get 3.64v drop on 25mm, 40M run, in a void, multicore General PVC cable on a 63A but with 52A load - using cable-mate programme.

 

[morph]

life in the old dog yet then LOL

 

[ukpablo]

cheers guys................just wanted other opinions on this