Electrics: blown something up (again)

You had a high resistance joint in the cable somewhere, and the welder has just found it for you.... unfortunately you wern't quick enough to look for where the smoke was coming from so you'll have to test the cable run to find the problem.

I very much doubt that the garage CU is directly fed from the incomer. Presumably it is fed from a way on the main CU in the house, or possibly a separate fused switched box close to the main CU. In which case either of the fuses may have blown.

AWEM

Well chances are you have suffered a "lack of discrimination" i.e. there is an upstream protective device that has tripped/blown before one in the garage CU got a chance.

You need to find where the power feed *to* the garage CU comes from. It might be an MCB in the main house CU - but if you say none of those are tripped, then it could be a separate box of some description.

Is there a RCD in the garage CU? If not, what about at the supply end?

There are RCDs in the garage CU (as part of its MCCB) and also next to the main incoming supply & meter. The one next to the meter may be the feed to the garage, I can't be sure. I'm guessing it is, because again, there's no voltage on either the input or output side of it and its "test" button does n't work (not surprisingly if it's unpowered). Unfortunately, to go back ev en one step before that requires breaking company seals. I'm just strugglin g to see how a company fuse can blow as a result of a 13A plug fuse blowing when all the protection in between remained un-tripped!

Do you have two electricity supplies and two seperate bills?

If not and the housen still has power then it's not a blown house supply fuse.

I'm guessing the garage has its own old-style fuseway immediately after the meter and before the house's CU. This fuseway feeds a cable run to the garage's own CU.

There are RCDs in the garage CU (as part of its MCCB) and also next to the main incoming supply & meter. The one next to the meter may be the feed to the garage, I can't be sure. I'm guessing it is, because again, there's no voltage on either the input or output side of it and its "test" button doesn't work (not surprisingly if it's unpowered). Unfortunately, to go back even one step before that requires breaking company seals. I'm just struggling to see how a company fuse can blow as a result of a 13A plug fuse blowing when all the protection in between remained un-tripped!

You have to find where the cable for the garage originates in the house. The source of the problem is likely there.

One possibilty is that the garage is run of a spur off your house ring main.

Is there a spur unit (switch & fuse thingy the same size as a socket) around the place that seems to have no function? It may be for the garage.

So, the CU in the garage with (presumably) its 32A power MCBs, is fed from a 13A fused spur in the house?

Can you do us some photos so we can have a look?

wouldn't be the first time, just because there are 32 amp mcb's in a secondary consumer unit, dosent mean it's fed from a supply capable of taking that current.

Dad's place had the loft sockets wired to the lighting circuit, found that out when he tried to use a hoover up there.

My garage is fed with about 5 meters of 6mm T&E, from a 32 amp rcd in the main consumer unit next to the incomer and meter, but i have a 100 amp main switch then a 32, 16, 6 and 6 amp rcd, dosent mean i can pull 60 amps in the garage,

Where can I upload photos to? Is there a binary group suitable?

Quite. In fact when I put a new CU in the garage I discovered that despite its modern appearance and loads of 13A sockets, there was no earth anywhere! The "electrician" had forgotten to connect it up!

There are at least hundreds of photo sites including Flickr, cloud storage sites with public access such as Dropbox, and other options.

OK, I hope this works.....

Sorry it's sub-optimal. I cannot see any voltage either side of the RCD to the bottom left of the meter so I'm guessing it's something under company seal that's causing the problem.

That shows as a really tiny picture on my phone, however, there is a switch with a fuse at the top left, is that the garage supply? If so, have you checked that fuse?

Yeah, sorry about the pic. I have checked the fuse and it's fine. I simply don't know if it's the feed to the garage. I think I'll call the leccy co. in the morning and ask for permission to break the seals....

As Adam pointed out, if you only have one supply (i.e. one meter) then you will have only one master incomer fuse. If that had blown, you would have no power to any of the house.

I have seen it done in the past.

Then your voltage tester is faulty or you can't use it correctly, or you have no supply, or you have no idea of the topology of your electricity supply for your garage/house, or you have an unmetered connection for your garage.

My guess is your garage is fed from a plugtop hidden behind some furniture :)

Either way at this stage it's probably best to call an expert in before you kill yourself.