What size mcb?

[nabby68]

Hi Fellas,
I intend to run a length of 4mm 3 core swa from the cu in my house down to my outhouse which is approx 35 m away. This will supply a mini cu with 3 circuits 1 lighting (10 x 50 w) and two 20 amp radials for sockets each radial has 3 sockets on each. It will be used for a band to practice and the heating side in winter will be with portable gas heaters nothing heavy duty will be used and just some table lamps. What size mcb should the circuit to the outhouse be protected by? I originally thought 32a bought have calculated (inc volt drop) that 20a maybe needed to protect the 4mm swa?

 

[ban-all-sheds]

The cable will take 32A, so as long as your actual load doesn't exceed 23A you'll be OK on a 32A breaker, EFLI value permitting.

OOI, given the effort in laying a run of SWA (properly), why are you bothering with 4mm² and not future proofing it with 10mm² so that when the band becomes successful you can install a hot tub for the groupies?

 

[nabby68]

The cable will take 32A, so as long as your actual load doesn't exceed 23A you'll be OK on a 32A breaker, EFLI value permitting

thanks ban. dont understand when you say the cable will take 32a but dont exceed 23a?

OOI, given the effort in laying a run of SWA (properly), why are you bothering with 4mm² and not future proofing it with 10mm² so that when the band becomes successful you can install a hot tub for the groupies?

i wish!!! The cost was a factor in this and if we ever do become that succesful hopefully the diff between 4mm and 10mm swa will be the least of my worries!

 

[ban-all-sheds]

thanks ban. dont understand when you say the cable will take 32a but dont exceed 23a?

I thought you said you'd done the voltage drop calculations?

 

[nabby68]

sorry ban, yes your right. just re-read your post