New consumer unit, sockets and lights into garage?

I've bought some stuff today to do the electrics in my garage.

I've got a small consumer unit with 40a main but and 6&32a switches, I have 6 double sockets and 4 x 5ft strip lights.

First thing i want to do is wire up the lights. I want 3 lights on 1 switch and 1 on another switch, how do i do this starting at the consumer unit?

Cheers

This is my unit:

 

I have fixed the lights to the roof, connected wires between each and run some extra down the wall for a switch.

 

http://wiki.diyfaq.org.uk/index.php?title=House_Wiring_for_Beginners

 

Your supply cable goes in the top of the RCD unit.

Brn - L
Blu - N
Earth to the Brass bar on the top left of the Consumer unit.


The copper shorting out strip is the linking bar which is connected on the bottom side of the RCD, and the bottom of both MCB's. (You'll have 1 spare tab should you wish to add another MCB).

32A MCB, will be for the socket ring, wired in 2.5mm cable. (or downsize the MCB to 20A/16A and wire in a radial circuit)
Brown to top side of MCB, blue in the neutral block at top of unit, earth to the top left bar.


6A MCB for lights, wired in 1.5mm cable and in a radial.
Brown to top side of MCB, blue in the neutral block at top of unit, earth to the top left bar.


Connecting this back at you house gets tricky to explain due to, possibility of RCD's in series, nusiance tripping, separate buildings, earthing etc.

 

Electrical wiring in a garage is covered by Building regulation (part p ) so will need to either a) be inspected by the Local Authority Building Control or b) have an electrical safety certificate issued following installation.

Getting an LABC inspection and signoff usually involves 2 visits, once after first fix, and again on completion - call your LABC for an idea of costs.
A friendly sparky will probably want to advice you before checking your work and then issuing a safety certificate.

As far answering your question:

Lights:

Run a cable from the 6A trip to the first of the 3 lights using 1.5mm T&E, then run cables to the second and third light in a radial pattern (rather than daisy-chaining) regardless of the actual geometry - this way if there's a fault in light 2, light 3 is unaffected.

Run a cable (more of the same T&E) from the first light to the switch

Inside* the first light, get some 5A chock-block and cut 4 terminals. Connect the incoming (from the CU) t&E to the first 3 terminals(1=L, 2=E, 3=N). Connect the brown of the switch cable to the brown of the incoming cable (terminal 1), connect the blue of the switch cable to the so far unused terminal 4 on the chock-block. Connect the brown wires in the cables for the other two lights to to this terminal too (terminal 4). Ensure all the earths are common.

Connect the first light itself so the live feed comes from the 4th terminal.

*If there is no space inside the light fitting to fit the chock-block then get a terminal box and put the chock-block in there and run a short cable to the first light - personally I prefer this method, though it is less tidy.

The terminal arrangement should be as follows:

1 = Permanent Live
2 = Earth
3 = Neutral
4 = Switched Live

For the single light, it's exactly the same, only without the additional lights.

Mains:

Get some 2.5mm T&E and run a cable from the 32a trip to the first socket outlet.

Run another cable to the the next socket outlet and so on in a Daisy-chain fashion until you get to the last socket.

Run a final cable from the last socket back to the 32A trip.

It is important that each socket has a cable 'in' and 'out' and likewise the trip should also have at least 2 cables - this is know as a ring circuit, and essentially doubles the amount of copper feeding each socket (a single 2.5mm is a bit thin for a twin 13A socket which could in theory draw 23A).

Of course you could run radial 4mm cables to each socket, but after the first one you'll be wishing you'd used 2.5mm (and you'll struggle to get 6x4mm tails into a single breaker lol)

When you've done it all, go back, check and tighten up each and every screw terminal - solid copper has a habit of going a bit slack over time.

Hope this makes sense...

edit:

Looking at your bits list, I'd be tempted to ditch the 6A MCB and swap it for a 6A RCBO Connect it to the incoming supply independent of the RCD you have there. That way if you go sticking an angle grinder through it's power cable under your car at night then you won't trip out the lights as well as the mains.

When wiring back to the CU in the house, make sure it either goes on a 100mA RCD or not on one at all (just an isolator, or a 32A MCB)

 

Some interesting advice been given here...

I would recommend having a look/ask around and find a repulatable, approved electrical contractor and ask for an estimate/quote for the work. I dont want to sound condisending but I am an Electrician by trade and get this sort of thing quite alot and 9/10 its cheaper, easier and most importantly safer to get a qualified electrician to carry out the work.
The new installation and also the supply will need to be installed in accordance with the latest edition of BS7671, tested, certified and registered with the relevant bodies. Presumably you have buildings involved for the erection of the garage? If so they will need to see the Electrical Installation Certificate before signing off.

As I said above, I don't wish to sound like a douche. I fully understand and embrace the DIY spirit for most things, but working in the trade I would strongly reccomend the above. Or if you have someone who is willing and able to sign the work off for you, ask them to have a look at the installation and tell you what to do. Chances are their advice will be better than that of people on the internet who have not see the installation. No offence intended anyone

 

Thanks for the replies, I'll have a good read of all of them ASAP.

I put a plug on the lights and they work so that's a good start lol


Also put up my Christmas present clock which sets its own time!!

 

Could i go from the CU to the switch then onto the lights if the switch is close to the CU?

 

It's better to go from CU to light, as that way you have permanent mains in the roof with the lights, in case you want to put another switch or something in at a later date - say for example an external floodlight on a PIR.

 

There's no harm in taking the supply to the switch position at all. Would be my preferred method. This way all connections are easily accessible at the switch position for testing, future expansion etc. No messy junctions in the back of light fittings.
I'm assuming that the roof space is staying open and that all cables are being clipped direct to the roof timbers?
I would recommend that vertical drops to switches and sockets etc. are installed in PVC conduit or trunking to provide mechanical protection for the cables. Whoever signs the work off will want to see this.

 

I've just been looking at it and first i wired the switch in between the plug and light and it worked great off the switch.

Then i got a bit cocky and used the plug to supply the CU and then the 6a to supply the switch. Each time i pressed the switch the 6a and main switch tripped. I had the brown from the plug to the top of the rcd, blue to the top right rail and earth to the top left rail. I then had blue from the lights direct to the top right rail, earth to the top left rail and brown the the top of the 6a and brown also into each end of the switch.

 

I've fixed it now, the blue incoming wire was suppost to go to the RCD

I swapped that and the first 3 lights all work fine off the switch.

When I do the other one I'll send the power to the light as Skyrocketeer said so I can have a pie above the side door.

Thanks very much guy's

Here it is now (just needs the switch putting straight lol )


I fixed the wires onto a 2x1 along the rafters

 

you know what..that makes me mad.

 

What? Wonky switch?

 

yep.
it's a curse. always notice fittings,switchplates, etc lol

 

lol

Would a 'lv armoured 6943x cable' 4core, 4mm, 25mtr be any good for running from the house to garage?

I've got all the lights and sockets wired and working now so need to get digging.

 

See table 4D4A. http://www.elecsa.co.uk/Technical-L...ting/Current-Carrying-Capacity-of-Cables.aspx

37A ain't much if you have a heater on.

Personally I'd use 10mm and future proof yourself.

As stated above, connecting the SWA to you home is something best done by an electrician. Due to earthing arrangements RCDs and wiring methods used within the new install and the existing.
Its not easy to explain to someone who doesn't really understand.

No offence.

 

Non taken, thanks for the advice

 

I'm looking at the 10mm swa on ebay now. I've seen it for 2.55/mtr in 3 core (anywhere cheaper?)

Would there be any point in me using a 4 or even 5 core? Could the extra wires be used for anything? Should i lay it inside a ducting, i can get 100mm pipe and fittings very very very very cheap

 

eBay ? Go see your local electrical wholesaler. Buy cable made in this country. It's built to a standard and passes stringent quality checks. You'll also line the pockets of business's and their employees.

3c SWA is fine.

Ducting is not necessarily needed because the cable is protected with steel wire SWA = steel wire armoured. But the cable does need to be sunk into the ground at a depth which satisfies the regulations. It also needs to be marked with electrical warning tape.
3c is fine. Unless you have 3 phase ?

Finally this needs to terminated by an electrician. Who understands the earthing arrangements in your home. This cable has to be terminated with the correct glands and earthed correctly.

You may also need separate earths segregated from your house. Which is something which can't be explained over the internets