Feeding a Shed Cu from the main CU

[robbo777]

Hi I am putting a Small 2 way CU in a shed to feed 3 x double sockets and 2 x florescent lights. The run from the Main CU is 30m

I am wiring it in conduit and I will be using 4mm singles to supply it with a 20A Breaker at the main, is this ok?

Many Thanks

 

[robbo777]

Thank you for clearing that up robbo. How far is the lorry/shed from the main CU? Just wondering if 4mm will be adequate as you are feeding it from a 32A supply. Have you done the VD calcs?
Also, regarding the bonding, what spinlondon said.

The shed is just under 30m away from the main CU I have looked at table 4D1 Ref Method B and 4mm will carry 32A the voltage drop on that was 4.47% (10.5v) which is within the 5% drop allowed.
I can always Reduce this to 20A as there will never be that kind of power going through it, all he has in there is a chop saw, table saw and a few battery chargers and these will never all be being used at the same time.

I will do that with the bonding then and take a 10mm back to the MET

Many thanks

 

[Guitarist]

Have you allowed for the fact that your conduit cables are rated differently to your armoured in your calcs, plus did you say there will be several running together in the conduit, hence temperature factors? Just thinking aloud as it is an assessment job...

 

[robbo777]

Have you allowed for the fact that your conduit cables are rated differently to your armoured in your calcs, plus did you say there will be several running together in the conduit, hence temperature factors? Just thinking aloud as it is an assessment job...

I hadn't no, thanks for pointing that out. i will use a 20A in the main CU.

Many thanks

 

[robbo777]

I hadn't no, thanks for pointing that out. i will use a 20A in the main CU.

Many thanks

Which I was going to use in the first place as I thought it was a bit close but someone mentioned in one of the earlier posts that I could go 32A but they wouldn't have known to take the other factors into consideration either.

I bet you have quite a vivid image of this installation now thank you for all of your comments.

 

[Guitarist]

I feel like I know it well :smiley2:
Hope all goes well with the assessment