mini-explosion after fitting a replacement wall socket

[ralphwiggum]

Can anyone tell me what happened here?

I replaced a wall socket in my home last night.

I removed the old one, wired in the new one correctly, turned the power back on and everything worked as it should.

I then turned the power back off and fitted another new socket across the room. When I turned the power back on again, the first socket I had fitted blew. Upon inspection, one of the live cables had actually blown into two pieces.

Afetr cleaning up all the peices and re-wiring all works fine.

Why did this happen? Was there potentially a weak spot in the live cable? And if I wasn't there when it happened, would the house have burnt down?

Cheers
Ralph

 

[securespark]

Screwed through cable with M3.5?

Caught live on fixing screw for back box?

 

[ralphwiggum]

Pretty sure it wasn't that, the wire that blew was nowhere near the screws...

 

[JohnD]

Was the wire stranded, or a solid core?

Does your consumer unit (fusebox) have fuses or MCBs? Does it have an RCD?

 

[ralphwiggum]

Solid wire which initially looked in quite good condition (the house is very old, not sure when it was last re-wired)

Not sure if I have a MCB or RCD, but they didn't trip.....

 

[JohnD]

Something fishy here.

Solid-core cable is difficult to blow like that. Under overload it would tend to just get hot all along its length, and the fuse would blow.

Under a dead short you would need a bad weakness to damage the cable before the fuse went.

If it was not stranded (i.e. spare whisker making a short) then there must have been (1) something wrong with the cable, like having been repeatedy bent and having a fracture, or damaged by a screw and (2) something wrong with your fuse or MCB so it didn't trip and (3) perhaps another fault in the ring (you have got a ring?) as current will tend to flow round the "other way" if you have a single break. There may also have been an error in the way you connected one or both of the sockets.

Go and have a look at your consumer unit and describe what you find.

 

[ralphwiggum]

Thanks John

I'm not at home now, will check the consumer unit when I get home.

Whatever is in there definitely didn't trip, because everything is working now and I didn't even check the consumer unit...

The switches are on a ring.

Ralph

 

[plugwash]

my guess is a double fracture scenario, with the fracture at the first socket being a "high resistance but still just about connected" and the fracture at the second being a "totally disconnected".

so after the second fracture happened other load between the sockets was only connected through the fractures and the one that ended up taking the current blew out.

if my theory is correct then you have another fault which is breaking the ring which must be found and acted on ASAP.