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Hello. Long time reader but not many posts. After more of a bit of insight than anything else as I have asked for a local electrician to come and have a look next week (unless anyone reading is near BS39 in Bristol/Bath and wants to have a look).

I have a washing machine (couple of weeks old as previous one had bearings failing) and a tumble dryer in my utility room. Both appliances are individually plugged into single sockets under the counter which are separately fed from 2 FCU above the worktops. Both FCU are fitted with 13A fuses. Have been happily (I think) like that for 6 years since the house was rewired and had new consumer unit fitted just after we moved in and had solar panels installed.

Couple of days ago washing machine stopped working. Assumed it was an unlucky new appliance to Samsung sent out an engineer. He spotted (quickly) that the plug was damaged and the socket starting to melt through. He then spotted that tumble dryer plug was even worse and socket properly melted through. Good news is the new washing machine doesn't seem to be broken after all. Bad news is both sockets and both appliance plugs are broken. I removed the fuses from FCU, isolated the MCB and unscrewed the sockets to find wiring inside is blackened and a bit melted.

Obviously I'll need the wiring and sockets replaced and the circuits tested but I'm after a bit of insight (I appreciate it's a bit of guesswork from afar) as to:

a) what causes this sort of damage?
b) why it may have happened to 2 separate sockets and plugs being fed from 2 different FCU feeds in short succession?

Thanks in advance,
Cameron

Melted socket, plug and wiring IMG_5825.JPG - EletriciansForums.net
Melted socket, plug and wiring IMG_6237.JPG - EletriciansForums.net
Melted socket, plug and wiring IMG_1492.JPG - EletriciansForums.net
 
Are both appliances from the same manufacturer?

I would say that looking at that, there is a loose connection ok the circuit/s somewhere. Are they both on the same circuit?
 
Are both appliances from the same manufacturer?

I would say that looking at that, there is a loose connection ok the circuit/s somewhere. Are they both on the same circuit?

Hi. No, washing machine is brand new Samsung and tumble dryer is 3 year old Hotpoint. Both sockets are on same 32A ring but each socket is fed from a separate 13A FCU on that ring with it's own cable between the FCU and socket (hope that makes sense).

Thanks,
 
Hi. No, washing machine is brand new Samsung and tumble dryer is 3 year old Hotpoint. Both sockets are on same 32A ring but each socket is fed from a separate 13A FCU on that ring with it's own cable between the FCU and socket (hope that makes sense).

Thanks,
No that makes sense. My money is on a loose connection on the circuit then.
 
No that makes sense. My money is on a loose connection on the circuit then.
Thanks. Do you mean loose connection(s) at the sockets the appliances were using (and just bad luck the both of them at similar time) or could the loose connection be somewhere else on the ring that somehow manifests itself at those sockets? As you can tell I know little about electrics but would like to understand.
 
Thanks. Do you mean loose connection(s) at the sockets the appliances were using (and just bad luck the both of them at similar time) or could the loose connection be somewhere else on the ring that somehow manifests itself at those sockets? As you can tell I know little about electrics but would like to understand.
It could be anywhere on the circuit, without the correct test equipment it would be near on impossible to find out where.
 
I would say the problem is localised to the particular sockets, and whilst melted plug / socket pairs are often caused by a problem in the plug, in this case it does look more like the sockets. Either poor manufacturing causing high resistance contacts, or bad workmanship in terminating the circuit cables. Seeing the back of the socket would probably reveal which of these scenarios.

My reasoning is that the heat pattern is the same in both cases, one on the line and one on the neutral, and reflects the layout of the metal parts within the socket. The internal construction of plugs is quite different between line and neutral, and in a decent moulded plug there is little chance of a high resistance in the neutral.

If there are more of these sockets around the house, or more of the same person's work (as the case may be), then there may be more burnouts to come on heavily loaded sockets, unless they are replaced / rewired.
 
I would say the problem is localised to the particular sockets, and whilst melted plug / socket pairs are often caused by a problem in the plug, in this case it does look more like the sockets. Either poor manufacturing causing high resistance contacts, or bad workmanship in terminating the circuit cables. Seeing the back of the socket would probably reveal which of these scenarios.

My reasoning is that the heat pattern is the same in both cases, one on the line and one on the neutral, and reflects the layout of the metal parts within the socket. The internal construction of plugs is quite different between line and neutral, and in a decent moulded plug there is little chance of a high resistance in the neutral.

If there are more of these sockets around the house, or more of the same person's work (as the case may be), then there may be more burnouts to come on heavily loaded sockets, unless they are replaced / rewired.

Thanks. Pictures of rear of each socket below. Fortunately (maybe, if that is the problem) these are probably the only 2 of this make and done by this installer as after he'd done the rewire I then (about a year later) got all the fixtures replaced with brushed chrome ones (different installer as couldn't contact original person) but left these two as they were behind appliances.

Melted socket, plug and wiring IMG_8968.JPG - EletriciansForums.net
Melted socket, plug and wiring IMG_2691.JPG - EletriciansForums.net
 
On a different note, is there any benefit in asking for the replacements to be flex outlets as they are fixed appliances which don't really get moved rather than plug and sockets?
 
The problem is now those burnt conductors need cutting back and extending so another joint. An outlet plate is a better option but it may put off service engineers. I would personally fit some Crabtree sockets with good quality plugs fitted by a competent person.
 
On a different note, is there any benefit in asking for the replacements to be flex outlets as they are fixed appliances which don't really get moved rather than plug and sockets?
removing plug from the appliances would almost certainly immediately invalidate the warranty on that nice new machine you bought!
its hard to say if there are other loose connections or terminations on the circuit that have high resistance, its possible it only showed at these sockets as they were under high load and combined with low cost / quality sockets failed much sooner.
It does look though as if the most significant melting happened behind on the cable which makes me think poor termination and contact resistance.
when the electrician comes out and tests the circuit, make sure the replacements fitted are of a decent make, Hager are a good choice,
out of interest is there much slack in the cable that can be pulled down to re terminate? as the wires look quite badly damaged.
Not wanting to step on another sparks toes as it were, I am based in central Bath and BS39 is quite a large area - you could be quite close or quite a bit out, but if you get nowhere with the electrician or want a second opinion then drop me a message. I can come out and have a look.
 
Quite an easy fix for any spark, just make sure you buy some decent accessories. Brands like Hager, Click and schneider, dont go for the budget range, they're going to need re-terminating due to the corroded insulation.
 
Cutting off and changing plugs does not invalidate the warranty. Just as well as that new machine needs a new plug now anyway.
Flex outlets are not a good idea, one reason is it makes them a pain to service.
You should not have FCUs feeding the sockets either as the plugs are already fused. If you want above counter isolation (which is not a requirement) it is best to use 20 amp double pole switches.
 

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