Unknown electrics

My mother has a single socket under her kitchen worktop which she currently has both the dishwasher and washing machine plugged into via a 13amp multisocket. Obviously if she turns both on at once the fuse blows in the multisocket, so she doesn't. I've just made an exploratory investigation to see if I could change the single for a double to make things a bit easier. I'm assuming it would be safe enough to run two 13amp appliances from a double socket on a standard ring main, am I right?

Anyway, she evidently doesn't have a standard ring main. Rather than finding the two cables I was hoping for going into the socket, there is only one. The outer sheath has been cut back so far that I can't see it. The three cores (?) are stranded, but are substantially thicker than the usual 2.5mm twin and earth, I would guess they are 4mm. They are sheathed in PVC, the earth is plain green and the other two are grey. From what my mother can remember the wiring there dates back to the early 80s.

What I'm asking your collective wisdoms is what this is and whether I can safely put a double socket on it which will draw 26amps (sometimes). I'm guessing it's a radial circuit, but I await your thoughts.

Many thanks,

Martin

Reply to
Martin Pentreath
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I'd suggest erring on the side of caution until you know where the other end goes. For all you know it could be terminated in a plug-top plugged into a hidden socket somewhere..

sponix

Reply to
s--p--o--n--i--x

Slight amendment: the earth is stranded, the other two are solid copper.

I do know that the wiring was originally done by a pro, so it would have been done to the regs of the day (and I think we can rule out the other end being plugged into a mystery socket).

Reply to
Martin Pentreath

If all the conductors are stranded likely 7/0.29 which was 'ring' cable before metric. It's usually tin plated, so doesn't look like copper. The L&N will have seven strands, the earth three. Would date back to the early '70s at best.

Reply to
Dave Plowman (News)

IF it is copper (check) and IF it is a correctly wired radial (check that it isn't something like sponix says). Then you can fit a double. IF it is 4mm copper flat twin/earth then it is rated at 26A max. current carrying capacity (table 4D5A)

Reply to
Bob Watkinson

Ahem! whats the fuse rating in the multi adaptor? and have you checked to see if there is a fuse spare in the CU to see if the socket is on its own fuse?

-- Sir Benjamin Middlethwaite

Reply to
The3rd Earl Of Derby

I think it's actually 7/.029 inch strand dia, the next size up being 7/.036. If you have a micrometer youi can check the dia of the strands they should be 29 thou or 36 thou or even 44thou. I cannot remember the current carrying capacity but someone might have some old tables available. Regards Tom

Reply to
Tom

Oh! Just had a thought..

I remember reading somewhere about an aluminium mains wiring system that was used in the 50s/60s. It's not aluminium wire is it?

Problems occured as the ends of the wires corroded at the point they were secured by the brass terminals. The corrosion would cause high resistance, overheating and potentially fire.

From what I can gather installations using aluminium wire were fairly rare, but there must be some of it left out there to this day.

sponix

Reply to
s--p--o--n--i--x

No.

Reply to
Chris Bacon

How do you know?

sponix

Reply to
s--p--o--n--i--x

You're absolutely correct. Sorry for the typo. 7/0.29 would be a pretty healthy cable. ;-)

Reply to
Dave Plowman (News)

Good question (aluminium was used for a while).

No-one has yet suggested investigating the type, rating and labelling (if any) of the fuse (or circuit breaker, although that sounds unlikely) protecting the wiring to this socket. That could give a clue to the type of circuit we're dealing with.

Reply to
Andy Wade

I would have replied to A. Wade's contribution, but he's messed up the quoting. So: "Because "stranded" aluminium wiring wasn't used in situations like the OP mentions, or in such small sizes, and it wasn't used in the early '80s". That's about it, really.

Reply to
Chris Bacon

| s--p--o--n--i--x wrote: | | > How do you know? | | Good question (aluminium was used for a while). | | No-one has yet suggested investigating the type, rating and labelling | (if any) of the fuse (or circuit breaker, although that sounds unlikely) | protecting the wiring to this socket. That could give a clue to the | type of circuit we're dealing with.

My guess would be a spur off a ring, IIRC In the old 7/029 days you were allowed 2 * 13 amp sockets on a spur.

Reply to
Dave Fawthrop

I think you'll find it was used for small sizes for a while, from the late 60s to early 70s. Aluminium twin & earth appeared when the price of copper shot up and its use ended when it was 'banned', having caused a lot of trouble.

Aluminium is still allowed in house wiring, but only for sizes of 16 mm^2 and above.

Yes, the small sizes had gone by then.

Reply to
Andy Wade

I'm fairly sure that double sockets are rated for 13A total - not 26A total.

At least, every one I've seen has been marked Max. load 13A on the back.

M
Reply to
Mark

I'd suggest erring on the side of caution until you know where the

FFS DON'T MENTION PLUG TOPS!!!!! I mentioned it once, but I think I have got away with it ;-)

Reply to
Clive Dive

Check your consumer unit. You might find it's an unused cooker circuit, especially if your mother has a gas cooker.

Green-yellow was in use by the 1980s IIRC so maybe the wiring's older. The other cores should be red and black, regardless of age, so maybe someone's used some non-compliant cable. You should find out what else is non-compliant before doing any work on it.

If in England, Part P of the Building Regulations will apply.

Owain

Reply to
Owain

The core colours quoted by the OP dont tie up with what they should have been under any recent wiring regs. I'd be very suspicious as to it being a bodge.

Reply to
<me9

It's known to cause problems in the supply co. cables, where there is a leak in the outer sheath, and water gets in to corrode (and eventually sever) the conductors.

Reply to
<me9

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