volt drop outbuilding

[Jackflash]

Hi,

Looking to supply power to two outbuilding sheds to be used as an office (no electric heating required). one is 60m from supply source and another is 10m further on.

I'm currently debating what size supply / cable to install taking volt drop into account.

Ideally in unit 1 i'd have
-16a radial socket circuit
- 6a lighting circuit (1.3A Ib)
- 16a circuit to supply unit 2 sockets and fcu for lighting

This would give me a design current of 25.3A

Any ideas on what the best way would be to do this???? The volt drop gets a bit wild on a run this length.

Any thoughts much appreciated.

 

[telectrix]

6mm or 10mm would be my guess, leaning toward the 6mm and keep the load sensible. obviously , if there's a possibility of heating then go for 10mm. need to balance load/cost.

 

[jaydee81]

would allow for electric heating using a design current of 32 amp 60m run comes out as 16mm with volt drop of 5.57 volts

 

[telectrix]

16mm? be cheaper to get a new supply in. LOL.

 

[jaydee81]

just using doncaster cable calculator that what it came up with

 

[Jackflash]

The units have got log burners so heating isn't an issue. Perhaps i could use 10mm swa and daisy chain the 2 units and have individual cu's in each.

 

[Octopus]

Just make sure that when you quote, you state the maximum load, so when they later change their minds, as customers do, they will have to fork out for a new supply cable!

 

[Jackflash]

To work out the total volt drop, would i first work out the volt drop on the swa run to the 1st unit (60m) using full design current for both units 26.3A then add the volt drop of the second leg (10m) using the Ib of the 2nd unit (12.6A) then add the volt drop for the furthest lighting point in unit 2. Then add them all together and make sure it's less than 3% 6.9v. Is this right?

Does my design current sound a bit high? each unit is having 3 sockets and 3 lights. Sockets are for basic office stationary and domestic appliences only.
I've calculated it using 90% of lighting (2.3A)
100% of 1st socket circuit (16A)
50% of 2nd socket circuit. (8A)
26.3A
=====

 

[SirKit Breaker]

Dont forget to account for the derating factors! How is the cable to be installed? Dug in underground, pegged to the washing line? etc etc.

Cheers.............Howard