Major fault fire damage , any ideas ?

[Joethespark]

Wondering if I could put this incident to you and anyone could determine a fault scenario which would cause such damage .

A colleague was rewiring one half of a semi detached house. 3 phase cable head comes into the house which he is working , the neighbours mains come from the top of the fused cablehead ,through a conduit to another fuse and meter.

When removing a screw in the old consumer unit he shorts between earth ( screw) and the neutral bar.

Describes a crack and flash rather than a bang , next he discovers the combi boiler next to his consumer unit is smoking and thinks circuit board is fried .

Next he hears smoke alarms from neighbours house who was on holiday at the time !

999 - fire brigade dispatched .

There has been major fire damage in the neighbours consumer unit cupboard but luckily door was closed so fire mostly contained in there .

Supplier investigator reckons the lateral has caught fire , dispite having a fuse either end .

Scary stuff.

Only possibility he can think of is that one of the consumer unit screws was lodged into one of the neighbours tails which where coiled up with far to much excess behind HIS consumer unit .

There was a screw nick found on the neighbours neutral which was feed from the henley block on the side of the cable head but he can't be sure if it was caused by the screw in question.

Luckily he is insured but not sure exactly what has happened and still a little shaken by the incident .


Any idea what could cause a fault on the neighbours lateral of this proportion ?

Joe

 

[snowhead]

I'd guess there's a bit of the story missing.

Most likely cause of a fire would be 2 phases instead of phase + neutral.
Given the above facts I can't see how tho'

 

[Joethespark]

Forgot to add , only damage in his side was small burn mark from shorting earth/neutral . All damage at neighbours board.

 

[londonlec]

The neutral feeding next door was loose/open circuit, N-E link next door, next door was using your earth as a neutral, 3 phase supply = 400v through the house.

Just guessin' though ;-)

 

[Farmelectrics]

Say nothing and slip away into the sunset lol

 

[mechelec]

Is the supply TNS or TNCS ? Surely the neutral and earth should be at or about the same potential So why the crack when he shorted between the two. It does seem to suggest a neutral fault but then if it was a quick short how did the fire start? Did he disconnect a neutral somewhere he shouldn't have.

 

[telectrix]

leggit and scarper.

 

[stef]

Blue and black neutral / phase mismatch? Just. guess but it can happen

 

[telectrix]

i said these stupid new colours would lead to disaster. bloody europe.

 

[Joethespark]

TN-S system . Only removed his tails from consumer unit/meter .