sub main

[mcm]

hi all

need to run a sub main from main cut out to cu. what size swa would people use the run is about 4m max. would a 16mm be ok or would 25mm be best.

thanks

 

[telectrix]

all depends on the current demand of the sub. 16mm protected by a 63A. ?

 

[mcm]

sub will be supplying

electric hob/oven 12kw
2 x ring mains
2 x lighting
1 x smoke alarm
3 x outside lights
1 x boiler

as the supply is single phase and being split for two cu i was going to instal a 63amp fuse for protection for sub cable and to stop overloading to main cut out fuse. does this sound ok?

thanks

 

[Timbo_1975]

I did a rewire in a house recently which involved a sub main (well it was really the primary main to a 18w CU) and was cheaper and easier to do it in Concentric. 25mm from a 63a switch fuse.

 

[telectrix]

sub will be supplying

electric hob/oven 12kw
2 x ring mains
2 x lighting
1 x smoke alarm
3 x outside lights
1 x boiler

as the supply is single phase and being split for two cu i was going to instal a 63amp fuse for protection for sub cable and to stop overloading to main cut out fuse. does this sound ok?
16mm SWA is well happy with a 63A fuse.

 

[mcm]

regarding the 63amp fuse does it have to be a double pole or will it be ok to put a 63amp mcb in a enclosure to protect the sub main cable.

thanks

 

[telectrix]

it's ok if the main board will handle the extra load. and if you,ve got a non RCD protected way ( you don't want a fault on the sub-main circuits taking out half the main CU> personally, i would split the tails into henley blocks and fit a D/P 63A fused isolator, then the sub main is independent of the main CU.