Problem/question about electrics

[lawrie29]

When we moved house a couple of years ago, before we moved in we had a builder do a few bits of work to the house, one of which was to put an electric socket into the back part of the garage we had split of to form a cleaner area to use for the washing machine etc.

Now, I had started to note a funny smell when the washing machine was being run a while ago, and put it down to being an older machine with only a cold water feed, so thought it was the heating element playing up a bit.

However, the other day decided to investigate as the smel was noticably worse.

Turns out that the socket was over heating. OK, I though, washing machine pulling a lot of juice, change that to another socket, and just have the freezer running on that socket.

Went in again today and got the same smell, and again socket it really hot.

SO isolated the sockets, unscrewed the cover and the inside of the socket is starting to melt. Glad I took this action as it obviously could have burnt the house down!

Now, obviously, I will NOT be using this socket again, and will be getting a spark in to sort. But I was wondering what has caused this.

The socket has been wired correctly - brown live, green/yellow earth and blue neutral, though seeing as the neutral wire has melted a bit, can't tell if it was loose at all beforehand.

So, is it likely it was just a loose wire, or has the spark done something clever like swap the live/neutral round when he put the spur on?

Yes, before you ask, he was a registered spark, but don't have the builders number any longer (not good enough to keep!) to get him back to sort it.

So if anyone can offer any advice I would appreciate it.

 

[awp]

I'm not an electirican but .. .. ..

check all the wires in the socket and the plug are tightened up - if they are loose they could be arcing - which would cause an overheat. Make sure you have the correct size of fuse in the plug and that the supply is corrected fused at the consumer unit. If all of that is OK get a qualified electrician in to look at it.

 

[Steep]

As awp says, a loose screw can cause that, as can using too light a cable for the load.

 

[frank]

I have experienced a similar thing, a 45 amp on/off switch for the shower (if I remember correctly) which was outside the bathroom that was heating up and giving off a bad smell
while switched on. It was a relative who has been a qualified spark for more than 40 yrs who wired it up for me so no reason to mistrust him.
When he looked at it for me he told me one of the screws had came loose and he reckons this was the cause.
Never had the problem since they were all retightened. Also he mentioned if the wrong type of switch for the ampage had been fitted then it could heat up as well.

Not saying that was your problem...maybe so but I reckon your wiring somewhere along the line needs checked by a spark.

 

[cyclamens]

It is surreal but these screws in sockets can become loose over time. Had it happen on a few occasions.

Almost had a fire on our hands when we lived in France - Wiring over there is.......strange:shake:

13 amp ring or spur sockets need to be on 2.5mm cable while lighting is on 1.5mm. Not unheard of for DIY bodgers to use the lighter cable

 

[Splog]

The washing machine could also be the problem if the heater is drawing too much current. Can you meter to see what load it's drawing? certainly needs checking though.

 

[photon]

Maybe it's a bit damp in the garage, causing corrosion, which means increased resistance, resulting in the overheating...

 

[flossie]

screws come loose over time. particuarly if exposed to extremes of temperature (hot/cold)...like in a garage... Then they arc...and you getc corrosion...and it gets worse... worst case is that a spark could set dust or other stuff on fire, which might if even more unlucky ignite something outside the socket, etc...

This is why the latest wiring regs do not allow anything that's inaccessable have screw terminals - no more connector blocks under floor boards and so on. As well as the use of RCD's on all circuits - but prevention by good design is better than detection of faults!


Getting back to the OP, a washing-machine is heavy load (could be 3kW) which is the maximum load for a double-socket on its own. If you had a freezer plugged-in to the same outlet, you could easily be overloading it if both run flat-out at the same time, which would, over time, cause the insulation around connectors to melt and explain the "funny smell".

Regardless, you need to get a spark in to look at the whole thing, and replace various sockets and potentially more. Just because the work was done by a "qualified" spark in the past does not necessarily mean that its up to best standards or otherwise appropriate for the use its put to - either now or then!

 

[woof woof]

As an ex electrician...

Outlets do fail, as mentioned... screws come loose, dust gets, contacts corrode etc... so the first thing to do would probably be to swap the socket outlet... assuming that an intelligent decision is made that this is the likely fault and that's why you pays the sparkies the big bucks.

 

[Bristolian]

It is surreal but these screws in sockets can become loose over time. Had it happen on a few occasions.

It's not just that screws work themselves loose. Copper is a very soft material and wherever it is stressed (as at the point of having the screw tightened into it) it will tend to creep away from that point resulting in a loose contact. Copper wires tightened by copper screws have double the trouble.

Rather obscurely, the tighter the screw is done up initially the faster this creeping takes place. It's one of the reasons screw sizes are different for different sizes of cable (and hence current carrying capacity) - it acts as a crude form of torque limiting.

In industry it used to be common practice for all screwed contacts to be retightened every couple of years.

 

[lawrie29]

Thanks guys.

I have just knocked the power out and tried to tighten the neutral cable where the melting was occuring.

Apart from the plastic cracking as I did turn the screw, i was able to put about 3 turns on the screw to tighten the wire, so that was definately the issue. It didn't help that the back plate for the socket was designed to go into a stud wall (which it was) but was not fitted well and had come out of the wall more than once (is behind the freezer, so not too concerned as you can't see it and the little uns can stick their fingers in it) so this movement will have contributed to the wire coming loose.

I have made sure the socket cannot be used again, and will get a replacement socket sorted out.

Can I ask though, why would the RCD not trip with this happening? Is it because the circuit is not pulling more load through than it would normally?

Thanks again everyone.

 

[paulyoung666]

This is why the latest wiring regs do not allow anything that's inaccessable have screw terminals - no more connector blocks under floor boards and so on.

how would you spur off a ring main then ?

 

[onomatopoeia]

T
Can I ask though, why would the RCD not trip with this happening? Is it because the circuit is not pulling more load through than it would normally?
.

An RCD measures a difference in current between the live and neutral, indicating some of it is going ... elsewhere. Such as through a person. It doesn't detect a small amount extra current being drawn due to resistance inside the socket caused by corrosion or a bad connection (which is what makes the socket heat up). If it was a lot of extra current being drawn, the fuse in the fusebox (probably called a "consumer unit" nowsadays) would blow or trip, as that's what fuses are for.

Disclaimer : I am not a spark, the above could be untrue.

 

[Oggy]

I've been doing electrics and electronics for 35 years. I agree with the possibilities of screws working loose, coper compressibility and corrosion.

Two extra points -

1/. Dampness could also be the cause of your problem, although if you are only getting the smell when the machine is running, this is a less likely cause.

2/. If you have got to the stage where you are getting a burning smell, it may well be that the wiring is damaged and needs replacing.

One way or the other, not wishing to cause panic, if you are getting a burning smell, you need to turn it off and act quickly.

Bottom line, if you do not know about electricity, get a pro.

 

[lawrie29]

Thank you Mark and Roger.

The room is not damp, th only plumbing is to and from the washing machine, it is a nice dry room.

The burnt peice of wiring will need swapping, don't think the rest will.

Am convinced it was the loose wire.

and yes, I have turned off and stopped using the socket.

 

[gman]

don't think the rest will.

lol, seriously, get a spark. For the sake of £50-100 it's worth it over the negative possibilities!