Socket blowing fuse

[Suet33]

We are having problems with one socket which my husband has changed the front plate on. When he tried to attach the new front cover it singed the screw and blew the fuse. What could be causing this?

 

[ProDave]

It sounds like a cable got pinched by the screw and pierced.

 

[Suet33]

It sounds like a cable got pinched by the screw and pierced.

Nope - it happened as the screw touched the metal on the box - definitely no cables nearby!

 

[Murdoch]

Nope - it happened as the screw touched the metal on the box - definitely no cables nearby!

I suspect your husband has placed the cables poorly in the back box and the fixing screws are causing the problem.

Take the fixing screws out and see if the problem goes away

And at the same time check he’s connected the cables to the correct terminals

 

[Fleeting]

Possible a wire has been damaged by the back box and when the cover screw touches the back box it earths it hence the fuse blows.

 

[SPECIAL LOCATION]

We are having problems with one socket which my husband has changed the front plate on. When he tried to attach the new front cover it singed the screw and blew the fuse. What could be causing this?

He has either terminated something wrong or damaged a cable or both would be the most likely cause.

Is it an MCB or RCD or RCBO that is tripping?

 

[ProDave]

What tests has he done to verify the wiring is correct?

 

[Suet33]

Possible a wire has been damaged by the back box and when the cover screw touches the back box it earths it hence the fuse blows.

What tests has he done to verify the wiring is correct?

None - what would you suggest?? That’s the type of help we need O guess x

 

[binky]

Check the wires as they enter the back box, it's easy to slice the insulation on sharp metaledges if it hasn't got a grommet.

 

[johnb2713]

None - what would you suggest?? That’s the type of help we need O guess x

Take a photograph of the wiring behind the faceplate and post it on here.

 

[SPECIAL LOCATION]

None - what would you suggest?? That’s the type of help we need O guess x

I will ask again...
Is it an MCB or RCD or RCBO that is tripping?

 

[newfutile]

This sounds like as above a cable probably a live has been nicked and made the back box live , when the screw (which is earthed via the front plate) touches the now live back box the protective device will operate.
this also means that the power was not off and he lucky not to get an electric shock or worse .
this is all assumption of course but it’s my best guess from the information we have here.

 

[Chrisbee]

Neutral connecting to CPC (Earth) can trip an RCD, even with the circuits breaker off.
One possibility is an earthed back box and a neutral (or indeed live) has been connected to the sockets Earth terminal by mistake.

 

[newfutile]

If its a neutral it will not trip the rcd or RCBO until some current is drawn (though it could be as little as 30 ma if the rcd trips at 15), also it sounds like a spark occurred at the 3.5mm stud suggesting a short circuit.
this assumes its been wired correct and not live (line)to the cpc terminal and earthed back box

 

[Fleeting]

Don't think we will ever know.

 

[kerching]

If its a neutral it will not trip the rcd or RCBO until some current is drawn (though it could be as little as 30 ma if the rcd trips at 15), also it sounds like a spark occurred at the 3.5mm stud suggesting a short circuit.
this assumes its been wired correct and not live (line)to the cpc terminal and earthed back box

Oh yes it will if there is a voltage imbalance between neutral and earth. Seen it loads of times

 

[newfutile]

only because there is a load ,if there is no current flowing the cpc will not be able to divert current to create the imbalance .
it used to happen on the old dual (RCD) Residual Current Device boards when someone connects to the wrong neutral bar , or a shared neutral is connected across the 2 rcds

 

[Suet33]

Thanks all - problem now resolved! Wrong wiring (it will take him a while to live that down )

 

[UNG]

Thanks all - problem now resolved! Wrong wiring (it will take him a while to live that down )

In what way was it wired wrong

 

[Suet33]

In what way was it wired wrong

Wires in wrong places (new plate layout was different and he’d just copied the original pattern