Plug and socket melted

[Tully]

Hi, I have a washing machine one year old, plugged into a double socket wall socket (Lap make) no other appliances use the socket. The other night smoke came out of the back and a burning smell.

The washing machine engineer came and found that the plug socket had burnt. The wall socket wiring was sound and unaffected, the 13 amp plug was fine but the wall socket had burnt and the internal plastic melted. It a concern because I put it on at night and the children are asleep in bed. So Why didn’t the RCD breakers pick this up and what could have caused it Please ?
Tully

 

[EFLImpudence]

Loose connection. As the wiring and plug appear to be undamaged, suspect internal rivets of socket.
Examine it.

RCDs and MCBs do not detect such things.

 

[Taylortwocities]

I have a washing machine one year old, plugged into a double socket wall socket (Lap make)

That describes the reason for the failure. Replace the socket with a decent make, like MK or Crabtree.

 

[JohnW2]

That describes the reason for the failure. Replace the socket with a decent make, like MK or Crabtree.

Possibly the reason - but, to be fair, that is purely speculation. Even a cheap and nasty one should not burn/melt if conductors are terminated into it properly (i.e. not loose).

The last socket I saw that had suffered serious thermal damage was actually an MK one, the connections within which were extremely loose.

Kind Regards, John

 

[SimonH2]

It's "one of those things that happen". When the heater is going in the washing machine, then even a small amount of resistance will create heat. Heat can cause further deterioration - eg if hot enough, spring contacts will partially lose their pressure, and contact surfaces will oxidise - which creates further resistance, which creates more heat, which ...
Things like washing machines that never get unplugged have the downside that the contacts rarely get wiped clean - the rubbing action when the plug pins are removed and inserted wipes any surface corrosion off and leaves bright metal to make good contact. I've noticed when doing testing that I can find a socket that gives a high reading for loop resistance - so I pull out and re-insert the adapter a few times, and work the switch a few times, which normally fixes the problem.
I suppose the corollary of this is that a socket used for something like this doesn't get much wear on the contacts.

It's also one of the things that so called "safety covers" can cause. Not a single one on the market complies with the dimensional requirements of BS 1363, and some will over-stretch the socket contacts - reducing contact pressure (hence producing more heat and risking burnout) when the socket is later used for a high power device.
http://fatallyflawed.org.uk/html/size_matters.html

 

[JohnW2]

It's also one of the things that so called "safety covers" can cause. Not a single one on the market complies with the dimensional requirements of BS 1363...

That's true, and it is a theoretically possible (but, I suspect, never actually demonstrated/'proven') cause of subsequent contact over-heating. However, as you have said, things like washing machines and tumble dyers usually never get unplugged, and the sockets in question usually have always been used for those appliances, so there is usually little scope for "safety covers" to have been used in those sockets.

Kind Regards, John