Garage Wiring Problem

[tombrooker84]

Hello Guys,

I've been asked to install a new consumer unit, power and lighting circuit into a grage. The feed from the garage is currently fed from 3 single core 4mm wires running underground in a conduit, into a rewireable 30amp fuse.

I have tested all the 4mm wires and all are ok. What i plan to do is to install a 5 way board in the garage RCD protected (only running two circuits but customer said he would not be prepared to upgrade the cable but to leave some blank ways incase he would one day)) with one 20amp breaker for power and one 6 amp for lighting.

However it is the supply from to the board I am concerned about as it is already a submain. The rewireable fuse board is fed from a 10mm armoured from an switched fused isolator, where the tails are split. Can I leave the re -wireable fuse in and feed it from there as before or do i need to upgrade the fuse to an mcb by splitting the armoured cable into henley blocksand then into a 1 way fuse board.

Also only a 10mm earth going to the rewirebale fuse board. I am going to tt the fuse board in garage by installing an eartrh spike, do i need to upgrade the earth to 16mm at the rewireable board?

Sorry if I seem a bit hazy but been working in a maintenance position for the last few years, and just started to get back into domestic work.

Kind regards

Tom

 

[DurhamSparky]

one option is to RCD the supply cables from the CU..! rather than loop out the Current rewirable straight to the gargae box loop it into a standalone RCBO rated at 20 housed in a ip44 rated enclosure (get cheaper than the one i have shown at local wholesalers) and then allow it to run to garage to fit a 5 way CU, as if only using 2 ways (cant see customer stumping up more cash to extend more than he has) your covered for both RCD on circuits and RCD on Supply Cable!!

i based my thingy on this

2 Way Insulated Consumer Unit
20 Amp 30mA RCBO - Contactum
2 Way Insulated Enclosure - IP30 2 Module

 

[pushrod]

Also only a 10mm earth going to the rewirebale fuse board. I am going to tt the fuse board in garage by installing an eartrh spike, do i need to upgrade the earth to 16mm at the rewireable board?


Tom

If you have a 10mm line to the rewireable submain board, can't see why you would need a bigger than 10mm cpc for the distribution circuit, table 54.7 of BRB. (unless i'm not understanding your post)

 

[tombrooker84]

Cheers guys,

I was under the impression that I did not need to RCD the supply cable as it is mechanically protected by the conduit, so therefore I was just going to RCD the board in the garage, so that if anything in the garage trips you don't have to trapse all through the house to reset it. And also I have not tested the rewireable fuse board so do not know if anything on that board would cause nuiscance tripping or be at fault e.t.c if i was to install an rcd/ rcbo on it, I thought bny splitting the cable i would not be responsible for the rewirebale board?

Thanks for the advice on the supply earth as well.

What do you think is the best way of spliiting the armoured? I was thinking about running it into an adaptable metal box with Henley blocks inside?

 

[daniel hill]

as rcd goes you cud put a 100 mA in the house and use a 30 mA in the out house
or am i wrong