Advice on Burnt out wall socket

[Alex Woodall]

Hi All

Wonder if someone can give me a little advice on a burnt out socket I’ve found today:

Socket has now been isolated at the fuse board and is on a small ring with only 2 other sockets and a 30amp rcd.

Items plugged into the socket were a tp-link smart plug, with a lamp connected to it, and a 4 way extension lead with an Amazon firestick and a wireless router bridge connected. So nothing pulling significant loads.

Socket was installed about 10 years ago and there haven’t been any issues, that I know about, since then. We’ve recently had an extension built which involved replacement the fuse board (new FuseBox model).

Whilst I suspect it most likely that the issue was the live connection in the outlet, which is what has burnt, it feels like potentially too much of a co-incidence that this has happened just a few weeks after the fuse board was changed having been fine for 10 years.

Could the new fuse board have caused something to change here which has resulted in the socket burning out?

Thanks in advance for any assistance

Alex

 

[littlespark]

whatever was plugged in there will be damaged as well....

Coincidence... unless they removed that socket for some reason when they changed the board.
Its been a loose cable, and the heat caused by arccing.

You said it wasnt a big load... so im surprised its caused that much heat.

Im surprised you didnt smell it.

The back box appears to be only a 25mm deep one... A lot of decorative metal sockets ask for a 32mm.... maybe the live cables were close to the back wall of the box?

Did you mean a 32A, 30mA RCBO? or a 32A MCB with an upfront RCD mainswitch? (photo?)

Its a simple enough fix, but maybe beyond a DIYer.

 

[Avo Mk8]

Socket was installed about 10 years ago and there haven’t been any issues, that I know about, since then. We’ve recently had an extension built which involved replacement the fuse board (new FuseBox model).

Whilst I suspect it most likely that the issue was the live connection in the outlet, which is what has burnt, it feels like potentially too much of a co-incidence that this has happened just a few weeks after the fuse board was changed having been fine for 10 years.

Could the new fuse board have caused something to change here which has resulted in the socket burning out?

Littlespark has said it all before I finished, but I'll post anyway - these were my thoughts:

Has the advent of the extension resulted in additional loads being used on this particular circuit?
Or, for example, have you been using electric heater(s) on this circuit since it's got colder recently?

The socket is on a ring circuit, so a current of up to 10 or more Amps could be trying to flow through the connection between those two (burnt) brown wires (irrespective of whatever is plugged into that socket). The (L) screw terminal in the socket is responsible for maintaining a good connection between the brown wires, and quite clearly it hasn't done the job well, probably not having been tightened to the required torque in the first place.

This fault should have ben identified during the fuseboard change, if it was present at that time.
Have you got documentation from that work that gives figures for the ring circuits?

 

[Alex Woodall]

whatever was plugged in there will be damaged as well....

Coincidence... unless they removed that socket for some reason when they changed the board.
Its been a loose cable, and the heat caused by arccing.

You said it wasnt a big load... so im surprised its caused that much heat.

Im surprised you didnt smell it.

The back box appears to be only a 25mm deep one... A lot of decorative metal sockets ask for a 32mm.... maybe the live cables were close to the back wall of the box?

Did you mean a 32A, 30mA RCBO? or a 32A MCB with an upfront RCD mainswitch? (photo?)

Its a simple enough fix, but maybe beyond a DIYer.

Excellent thanks and definitely did smell the burning and that’s what directed me to this socket - perplexed as to why the fuse in the consumer unit didn’t trip though?

Builders didn’t touch anything in this room, unless they potentially took this socket out as part of the NIC testing, so must just be coincidence.

I didn’t think it was likely to be anything fuse board related but so strange that nothing for 10 years and then this happens 6 weeks after the fuse board is changed though!

Photos of fuse board attached

 

[Alex Woodall]

Littlespark has said it all before I finished, but I'll post anyway - these were my thoughts:

Has the advent of the extension resulted in additional loads being used on this particular circuit?
Or, for example, have you been using electric heater(s) on this circuit since it's got colder recently?

The socket is on a ring circuit, so a current of up to 30-odd Amps could be trying to flow through the connection between those two (burnt) brown wires (irrespective of whatever is plugged into that socket). The (L) screw terminal in the socket is responsible for maintaining a good connection between the brown wires, and quite clearly it hasn't done the job well, probably not having been tightened to the required torque in the first place.

This fault should have ben identified during the fuseboard change, if it was present at that time.
Have you got documentation from that work that gives figures for the ring circuits?

Thanks and very much appreciated

Loads on this circuit unchanged - it’s 3 double sockets that serve the media/av setup (sky box, led tv av receiver, router, and a couple of lamps). If anything it’s reduced as we haven’t got a fan connected to it anymore.

Haven’t had the NICEIC cert through yet - have chased up.

I would have thought something like this would have caused the RCD to trip though?

 

[Avo Mk8]

perplexed as to why the fuse in the consumer unit didn’t trip though?

There's no excess current flowing, just your normal (fairly light) loads. A high resistance joint has developed in a wire feeding the various items round the ring, so some watts of energy (heat) are generated, and this tends to be a runaway situation - heat increases the resistance which generates more heat etc. until something gives!
An RCD won't trip until there is an imbalance of current in L and N, and there's nothing here to create that imbalance unless a stray burnt wire develops a leakage to earth, which doesn't appear to have happened, or touches the metalwork, which would trip the MCB as well! (Or as Mainline has mentioned below - RCBO in your case!)
This sort of scenario is what the arc fault detection devices (AFDD's) were aiming to tackle, that are now mandated in various situations, but which don't seem to be attractive to many.

 

[mainline]

Excellent thanks and definitely did smell the burning and that’s what directed me to this socket - perplexed as to why the fuse in the consumer unit didn’t trip though?

Builders didn’t touch anything in this room, unless they potentially took this socket out as part of the NIC testing, so must just be coincidence.

I didn’t think it was likely to be anything fuse board related but so strange that nothing for 10 years and then this happens 6 weeks after the fuse board is changed though!

Photos of fuse board attached

View attachment 118630
View attachment 118631

If it's the one that is switched off saying lounge sockets it's a 20amp rcbo so maybe not a ring final unless it's been downgraded for some reason.