Garage Electrical Feed

[ryanwoodward]

Hi All,

I'm new to the forum and wanted to ask some advice on a job that is causing me a right headache. In short I have a detached garage which used to have an outbuilding attached to it. The outbuilding was demolished a while ago and before doing do so I disconnected a rats nest of a junction box to isolate it before knocking it down. When it came to reconnecting the garage I blew a fuse in the main fuse box and decided to leave it all disconnected so no power to the garage. I've made do with running a cable reel into the garage whenever I've needed power in there .

So it's been my nemesis for a while and want to sort it out. I traced all the wiring and thought I was good to go but I've hit a snag and wondered if you could give me some advice?

I have two feeds from the house going into the garage using pyro cabling. One of the feeds comes from the main fuse board externally running to a bulk head light above my front door. It looks like it has a junction box next to the light which then runs off to the garage. This is on a 15 amp fuse on the board.

I then have another fused spur by my cooker switch in the kitchen then running out to the garage again using pyro cable.

So I thought the cable from the main board is the lighting and the cable from the cooker switch is the sockets. (With having two feeds). I have hooked up the fuse from the main fuse board and I now have a live feed powering the bulkhead light I mentioned and have tested this in the garage and its live there too. 1 down 1 to go I thought. I then tried the same from the fused spur in the kitchen but was getting no power in the garage. The fuse is good in the spur. So I had a look in the spur and there doesn't seem to be a supply to it?!? It's connected to one end of the pyro and runs to the garage and then the other end of the pyro is disconnected. And this is what's confused me as I thought I'd nailed it in that I had two feeds for lighting and sockets.

Any advice you could give me? My initial thought seems to be dead in the water so I'm now thinking that the fused spur by the cooker switch was probably used to switch on an old security light which has been long disconnected. And 15amps seems to be too high for the lighting....so do you think this 15amps feed is for both and just a single supply? If so I would probably want to fit a garage rcd consumer unit so that I have the lighting and sockets on separate circuits. If so is 15 amps enough?

Any advice would be welcome at this stage.

Many thanks

 

[DPG]

I can't see any way of sorting this without doing some basic tests using your test meter. Anything else would be guess work. A sensible option may well be to take a fresh feed direct from the consumer unit to the garage. What's the earthing system to the house? Are there any bonding requirements in the garage? What RCD coverage is in place? Daz

 

[ryanwoodward]

Cheers Daz. At the minute it just looks like I have a single feed from the main consumer unit. The spur by the cooker switch only had a 3amp fuse in it which is why I'm now thinking that it was looped back from the garage for the security light. The garage will probably be gone in the next year so I'm reluctant to start spending big money to get it re done. If I have this single feed from the consumer unit and I chuck in a garage consumer unit to split out the lighting and sockets would 15amps at the consumer unit be enough? It's probably going to be used mainly for lights with the odd use of some power tools in there. What do you reckon?

 

[DPG]

Ah I'm with you now. To be honest you'd probably be ok with that for a few power tools and a florry. Just don't go start using big arc welders eh. Do the cables test out ok? Is there rcd protection? Daz

 

[Spoon]

Also need to answer Daz's question on the earthing system of your house.
What size is the cable fitted to the 15A breaker?
Does the house CU have a RCD. (As already questioned by Daz)

 

[ryanwoodward]

Thanks guys. In all honesty I cant answer the earthing question. The main consumer unit isn't rcd it's old fuses. It is a job I need to get done to swap it out for rcd. But in the meantime if I take the feed to the garage and put it into an rcd garage consumer unit that should protect me in the garage. In terms of the size of the cabling again it's not standard twin and earth it's old pyro. The cable is probably 5mm in diameter and the cores a couple of mm. What's the best way to test my earth? Once it's all hooked up if I chuck a socket tester on the sockets and it throws no earth errors at me am I good?

 

[Wilko]

Hi Ryan, want to ditch the existing cable and put in a new one? I like SWA for that job, but you must terminate and earth the armour properly . I have seen 2.5mm cable with 16A RCBO in main DB used for your situation and perform fine, until the welder arrives home. I used 6mm SWA and 32A with RCD cover and now I can turn my garage radio all the way up. Cheers, David

 

[Wilko]

No no no - no socket testers. You need to confirm earth continuity from the garage back to the main earth terminal (among other things) before making the garage live. I use a wander lead and a continuity tester. If you are not familiar with how to do this you should stop and seek assistance.

 

[Spoon]

You are not going to like my post but truthfully mate I would get an electrician in to test the existing cable, if you are going to use it.

 

[ryanwoodward]

Cheers Guys, I was just trying to reinstate the existing supply with the added protection of an rcd unit in the garage but I think you're right. I need to get the earth tested before I do anything else. Back to my cable reel!!! Haha. Thanks for all your help it's been really useful. Thanks guys.