The right cable size?

[kibble19]

Hi all,

I need a hand with getting the correct size of cable. I have a 300m run, with a 50kv load. It will be buried direct in the ground.
I have calculated it at 70mm 4core SWA with a 50mm separate earth (belts and braces), is this right?
Also, what would I have to back this up with, 60947-2, 125A?

 

[SYKRAPS]

For a 125a supply

Donny cables recommend 95mm allowing for a 5% volt drop or 150mm for a 3% volt drop, but you would need to confirm as you cannot add all of your criteria

Cable Size Calculator :: Doncaster Cables - Manufacturers and Suppliers of Cables Meeting British and European Specifications

 

[kibble19]

Thanks for reply, it would be 5%, as power circuit and not 3% for lighting.
It's to supply a house (staff quarters) from a sub main board in the factory, protected by 300a three phase.
would you suggest 50mm seprate earth as well?

 

[malcolmsanford]

Sky how did you get 125amps mate. I assume the 50Kv is actually 50kva and I assumed something that size would be 3 phase so got a load with a PF of 1 of 72-73 amps

 

[Guest55]

do you mean 50KVA as your load ?
have you converted it into amps per phase as the basis of Ib ?
what was it ?

 

[Guest55]

with a whopping run of 300mtrs the cable will be sized exclusively to volt drop really.
it will end up big enough to carry 3 - 4 times the load.

 

[SYKRAPS]

Sky how did you get 125amps mate. I assume the 50Kv is actually 50kva and I assumed something that size would be 3 phase so got a load with a PF of 1 of 72-73 amps

Just a presumption fron the 125a? at the end of the post, thought the OP wanted scope for expansion

 

[kibble19]

All the client said was it needed to carry 50kv for a house.

 

[SYKRAPS]

Yes I know, I read into the post more than I should have done.......still recovering from last nights ale.

My mistake

 

[scotsparky]

50KV for a house?? what is it Edinburgh castle?

 

[Adam W]

All the client said was it needed to carry 50kv for a house.

I'd get that in writing before trying to supply 50kv to a house.

 

[kibble19]

It's not just a house, he is having other stuff up there, like a log cabin etc.

 

[Adam W]

Are you planning to tap off at the transformer, or take the 50kv to the log cabin as well?

 

[HandySparks]

Thanks for reply, it would be 5%, as power circuit and not 3% for lighting.
It's to supply a house (staff quarters) from a sub main board in the factory, protected by 300a three phase.
would you suggest 50mm seprate earth as well?

Unless the house has no electric lighting, I would expect to size for a 3% volt drop.

 

[kibble19]

Haven't worked out yet, what to put at the house side. Will probably split the house levels across each phase.