Circuit design - Outdoor radial

[Chris Ward]

Can anyone shed any light on this for me.

Im putting in a supply to an outbuilding to supply a 13a water heater & 3a light, but picking a socket up on the way. Im wiring it in 4.0mm pvc twin cable from the DB, then 4.0mm 3core armoured outside. There is a DP switch incorporated near the DB in order to isolate the outhouse power from inside. The route the circuit will take is this:

(-> = Cable between)

(main building)DB1 -> 32a RCBO -> 32a DP Switch -> (goes outside) Outdoor twin socket -> (into outhouse) Un Switched FCU to supply water heater (13a fuse) -> Switched FCU for lighting (3a Fuse)

Im pretty sure this meets requirements for 433.1 Radial final circuit. Anyone got any input?

 

[pushrod]

Seems pretty good to me, should the water heater not have a double pole isolation close at hand - you can get DP switched FCUs.

 

[telectrix]

sounds good to me. make sure the SWA is properly glanded, the armor earthed at the supply end. might be an idea to fit a double metalclad socket in the outbuilding to gland the SWA. then metalclad FCUs.

 

[Chris Ward]

Armoured will be glanded accordingly & armourings earthed, and the FCU for the water heater is now a DP switched unit. Thanks for that input, well spotted.

I had someone query the double socket fed direct from the 32a supply which cast a seed of doubt hence the post. But as we know the socket is limited to what can be plugged in.

 

[telectrix]

Armoured will be glanded accordingly & armourings earthed, and the FCU for the water heater is now a DP switched unit. Thanks for that input, well spotted.

I had someone query the double socket fed direct from the 32a supply which cast a seed of doubt hence the post. But as we know the socket is limited to what can be plugged in.

not a problem. if you think about it, a " standard " ring final has sockets direct off a 32A supply, albeit wired in 2.5mm x2, ( for a ring final ) THE 32a MCB protects the cable, whether it be 2 x 2.5mm in a ring, or 4mm in a radial.