Lighting for the garage

johngti

oxoman said:

Running 2 supplies off a joint box isn't really the best way to do it TBH. What size cable do you have from the house board to the joint box and garage consumer unit. 65amp seems a big supply. Do you have spare ways in garage consumer unit and what do you intend using the sockets for in the new summerhouse. Ring main isn't really necessary. A small garage / shed consumer unit would be fine. What I will say is all the circuits in a summerhouse should be RCD protected. In fact under current regulations all circuits should be protected in this way. I'm guessing yours isn't.

I think it’s 2.5mm cable from the house and I could be wrong about a 65amp fuse too. Easy enough to check. The fuse board itself is fitted with rcds but, yeah, the feed outside is an isolation switch and a fuse. Unfortunately, the right way to do it will remain beyond our means for the foreseeable. Really at some point we need to get the house rewired I think.

johngti

I was wrong. It’s a 30a fuse

johngti

Ta. The idea is some sort of small heater and a couple of floor lights so nothing too heavy. I’d need to check what’s there I think, could easily be 6mm cable from the house. The other idea I played with was to swap one of the sockets in the shed for an rcd switch and spur a couple of sockets off that up to the summer house. Obviously there’s be no light circuit up there in that case but hey ho.

photonic69

I'm not a qualified electrician by any stretch of the imagination, though I have happily and successfully completely rewired a couple of houses and then had the install checked by a qualified spark before connecting to the main fuse etc.

Your planned scheme would be OK if the radial (which yours is basically a big radial) is protected by a 30Amp MCB at the main fuse board in your house so that any extra load that exceeds the design limit of the circuit would trip it and prevent overheating/fire etc. This would be annoying as all the power and lights would fail together. However, the issue lies in that the load could easily be exceeded by powertools, heaters, lighting, fridges, cookers and othe items, not neccessarily by you but maybe future owners etc. If a fault causing damage arises then you probably won't be covered by insurance.

Here are a few links that describe the work you propose so worth a read and view (videos), even if they are a bit long winded it will give you some useful pointers.

https://electrical.theiet.org/media/1695/electrical-installations-outdoors-a-supply-to-a-detached-outbuilding.pdf

https://www.youtube.com/watch?app=desktop&v=Ryx5rgvUf00

https://www.youtube.com/watch?app=desktop&v=aEnz4VgtIe8

johngti

Thanks. I’ve been thinking on today and it occurs to me that having a fuse on the cable coming from the main panel sounds great but if anything happens to the cable between the house and the RCD in the shed, there’s no real protection against electrocution! It’s a weird set up, obviously been there for years. Basically it’s like:

Feed->switch->30A fuse->junction box->swa (badly installed!) through the wall and then into the diagram I stuck up yesterday

At the very least I suspect it’d be sensible to swap out the dodgily installed junction box for a small consumer unit with an RCD fitted so I can terminate the swa properly. Probably ~20A/30ma? That way I’m safe using 2.5mm cable onwards as I understand it.

johngti

And more reading now makes me think I should get an rcd in place of the rubbish junction box in the house, take the rcd out of the CU in the shed and replace it with a main switch because the shed circuits are protected by MCBs anyway and then use a spare way off the shed CU to run a spur for sockets up to the summer house.

And breathe.

johngti

Yeah, the drawing was a little simplified! The swa doesn’t feed into the fused switch. There’s another JB in the house but the armour from the cable isn’t earthed. I reckon I could fix that problem as well as making the cable itself safer.

Thanks for the help, it should all be so simple!! Think I’ll do as proper a job as I can for now in lieu of ripping the whole lot at at some point in favour of a new CU

daniel_b

Evening all, picked up the lights, switch and cable today - discovered one twin light was badly damaged (Looks like it got crushed in transit) so took that back for a refund, planning to try it with 3, and then re-purchase the extra one if need be, but suspect it may well do as the 3 I now have.

Wiring proving a little more tricky than I had envisaged, so have not gotten very far yet - have taken the easy step of putting the two single light brackets up on the joists, as much to get them out of the way as anything, to prevent damage.

As I said I went for the IP20 variant, and this has a central access point with connectors (No earth), and one of the ends has an access point and connectors (Live, neutral and earth that terminates to the chassis) as well.
As I am going to run two of them up against the joists, I'm planning to ignore the top access point, and concentrate on the end ones for each.

The instructions are pretty poor in my opinion, given it states you can daisy chain them it gives no instructions on how to do it, which seems bizarre, especially as it states in the instructions how many you can daisy chain - 5 seems to be the max.

So as there appears to be two ports each for live, neutral and earth, my plan is to have the one set of leads coming in from the switch to light number 1, and use the left set for example for the inbound power, then use the right hand set of ports for the outgoing power to light number 2 - and so on along the chain - does that make sense, and seem correct?
I've tried to illustrate it (badly) below using paint!

The other bit of confusion I am having is with the MK light switch - I have what I believe to be a basic 1 way switch, and on the back I have 3 ports with screws in them.
At the top I have 1 & 2, and bottom right I have COM - SP is there but is empty, by design I am sure.

This is the back of the light switch - too - if anyone could advise which wires are meant to go where that would be very much appreciated, but I will still trawl the internet for suitable diagrams.

daniel_b

Hi @oxoman thanks so much for the reply, and advice.

I'd rather get the right switch, would this be appropriate:
https://www.screwfix.com/p/mk-logic-plus-20a-1-gang-dp-control-switch-white/44956

Presumably that will change what I then have to do with the 2 neutrals and 2 earths?

Re the white connectors, yes these are integral to the lights, and un clip for access.
Pleased to know I at least have that bit right!

Presuming I am still going to end up with at least one cable external from the switch, would some kind of junction box be a sensible option to house it/them?

daniel_b

And this is the cable I bought @oxoman
https://www.screwfix.com/p/time-3183y-black-3-core-1-5mm-flexible-cable-50m-drum/588fj

And would this be suitable to link the earths and neutrals?
https://www.screwfix.com/p/debox-in-line-junction-box/8692h

daniel_b

oxoman said:

That cable will be a bit thick tbh, .75mm or 1mm would be sufficient for your needs. You might possibly struggle to get it in the light fitting connection. 1.5mm flex will take upto 13amp easily, way above what you need. The double pole switch will switch both the live and neutral so you just need to connect the earth's together. You will have Live in and live out and the same for the neutral. Dont forget you need a deep enough back box for the switch.

Thanks @oxoman, you are spot on sir, popping the 1.5mm cable into the end connector ports, I can see it is going to be too much of a squeeze to get one in, and one out, so I've also now ordered 25m of this 0.75mm cable:
https://screwfix.com/p/time-3093y-white-3-core-0-75mm-flexible-cable-25m-drum/177jy
The actual cables themselves did fit into the connectors, but I think with the 0.75mm cable everything will be a lot simpler.
Would it be safe for me to run the 1.5mm from the fuse box to the switch, and then change to 0.75mm from the switch out to the lights?

I picked up the small junction box, but haven't had the time to progress much today, have a couple of days off at the end of the week so will tackle it then.

Still not quite worked out how to route the earth and neutral satisfactorily to the junction box, whilst the earth alone goes into the switch - and will have the same 'issue' when they come out the other end - thinking to mount them side by side on a wooden plinth which in turn will be secured to the door frame and nearby window frame.

A friend suggested two individual small connectors within the pattress box - I bought a 30mm (Looks like you can get a 44mm one too) one as I wanted plenty of room, and am not worried about how it looks.

This is what they have recommended, looks like you go in one side, and back out the other for cable number 2, not unlike the connectors on the junction box and those fitted to the lights.


That would certainly get around the routing issue in the main, but not sure if that is a sensible idea or not.

daniel_b

Evening all,

Completed this today, probably took me about 4 hours of not constant work, and taking my time.
The trickiest part was getting the two wires into the daisy chained light clips, but managed it with the help of some angled narrow nosed pliers.
Delighted with the result, 3 lights is just about right I think - 4 would have also been fine, but I can't see any real need, although really easy to add at a future juncture should I want to.
The little Wago 221 connector is a joy to use, super easy.

A massive thankyou to all those who offered their advice, and pointed me in the right direction, especially @oxoman - GREATLY appreciated Sir