Help with Garage Electrics please.

[Danno7]

Hello
I am new here so apologies if this is the wrong place for this thread or it has been asked before.

I am upgrading my Garage electrics and would like some advice please.

It is detached and is currently fed via 6mm SWA from the RCD side of my Consumer unit.
I want to renew electrics in garage to:
4 Double metal clad Sockets
2 Fluorescent Light units
2 Metal clad Switches (2 way lighting)
A new Metal 4 way Consumer unit.

My questions are regarding the consumer unit.
1) Do i need to buy a dedicated "Garage" Consumer unit or can i buy a Metal Consumer unit and install my own MCB's ?
2) Do i need a RCD built into the Consumer unit or is the RCD on my Household C/U adequate ?
3) In the future i will be adding security lights and Garden lights. Should i buy a 4 way unit or do you think a 2way would do ?
4) I know i need 6A for lights, 16A for the sockets but will another 6A be ok for the outside/Security lights ?

I want a 4 way unit just to isolate the internal lights from the outside lights for maintainence etc.
It is also going to be installed by a competant Part P qualified person.

Hope i've given enough info but if not, i'll try to give more when asked.

Thanks.

[mark_the_spark]

1) Do i need to buy a dedicated "Garage" Consumer unit or can i buy a Metal Consumer unit and install my own MCB's ?
Nope any C.U. will be fine, I take it its not going to subjected to rain etc...
2) Do i need a RCD built into the Consumer unit or is the RCD on my Household C/U adequate ?
So long as there is an RCD it should be fine, although you might want to take into consideration nucience tripping if something does wrong
3) In the future i will be adding security lights and Garden lights. Should i buy a 4 way unit or do you think a 2way would do ?
Id get a 7-10 way, not a lot of difference in price
4) I know i need 6A for lights, 16A for the sockets but will another 6A be ok for the outside/Security lights ?
Yep, that will be fine

Also please note that when working outside of your equipotential zone (your house) your electrical supplier will sometimes insist on a TT system being installed (your meant to tell them haha) and the garage earthing being seperated from the house earthing.

PS what size MCB are you using from your house C.U.? 20a?

[Danno7]

The SWA is coming off of a 16A MCB in my House C/U.

As for the TT system, i'm sure my installer will tell them, haha !

Surely if the SWA is run from the RCD side of my C/U, this would surfice, safety wise ?

My current electrics in the garage have been run from this since my Household Consumer unit upgrade 3 years ago...And well beyond that judging by the state of them ( Bakelite, Vulcan wiring and all !!!!!!)

Cheers Mark

Oh !
Forgot to add, As reguarding Nuscience tripping, Would an RCD in the Garage C/U be overkill considering there is one in the Household C/U, or would this help ?

Thanks

[Jason.S]

Originally Posted by Danno7

Oh !
Forgot to add, As reguarding Nuscience tripping, Would an RCD in the Garage C/U be overkill considering there is one in the Household C/U, or would this help ?

Thanks

IDEALLY you would have the house end MCB on the non rcd side of your CU.

This then would make the garage totally separate from the house and have its own RCD main switch, which would then avoid tripping the house RCD should a fault occur in the garage.

And no, its not a good idea to have 2 x 30mA rcd's in line.

[Danno7]

Thanks for the advice.
I will leave the SWA on the RCD of my House C/U.

And will get a Metal 5-7 way unit for my garage (non-RCD).

Thanks all

[Danno7]

Quick additional question.

The garage C/U will be connected by SWA to the household c/u and it's earth system, i know i need to install an Earthing rod as this garage installation will technically be a TT system.
I do then disconnect the SWA earth on the Garage c/u end ? Yes ?

By the way, it will all be installed by a semi Competent person...Myself, embarking on my 1st Big(ish) install. I have my part P, VRQ level 2 and Just need to get all the theory into practice.
Because i am not yet joined to napit or nic, could i get local authority to check, test and sign this off or should i get a Full Part P qualifies electrician in to test and check/sign off ? And Would this be allowed ?

Thanks.

[magic-sid]

You wont be able install everything yourself and then get a part P registered spark to sign it off, If you know someone who is registered it would be ideal to work alongside them, that way they can see any work your doing is complying . They would need to see the whole install though.

Rather than paying out for them to come over and give you a hand you could offer them your time, labouring. on there own work.