Burnt-out neutral busbar

[securespark]

I had to go to this on call at lunchtime today.

The customer complained of sparks flying out of the CU.

You have turned it off, haven't you? I asked her.

Oh, no, the washing machine, tumble dryer & dishwasher haven't finished yet......

 

[bernardgreen]

Perhaps electro convulsive therapy should be apploed to the customer.

 

[securespark]

A loud crackling, sparks and a very strong smell (so strong I could smell it 3hours after it started) of melting plastic would make most people think "Hmmm. Better switch that off!"

Not this one!


That neutral busbar is almost in two pieces.

 

[JohnD]

wipe it over with a damp rag and put it back together, there's years of life in it yet

Was it loose screws?

 

[Lectrician]

Loose screw on RCD I assume.....Or the busbar stab on the wrong side of vice-type terminal.

 

[securespark]

Yup, a loose terminal screw on the outgoing neutral terminal of the RCD.

Next to that brown on the RCD.

 

[plugwash]

looking at the dismantled picture i'm guessing the fault started at one of the outgoing screws (probablly for the kitchen ring) since that is where the bulk of the damage is.

the area that connects to the RCD looks in pretty good shape (other than some minor heat damage)

 

[JohnD]

Was the sticker missing?

"check tightness of all screws, including factory fitted ones"

 

[securespark]

Minor?

What you couldn't see was that the RCD casing had begun to drip onto the CU base.

That screw you see there was absolutely tight. You could ascertain that despite the damage.

I think the reason it is sootiest there is because it is much weaker & thinner at that point.

 

[securespark]

Was the sticker missing?

What? GE boards with warning stickers like that? Get away!!

No, these boards don't have warning stickers.

 

[RF Lighting]

Not as good as mine last week

 

[securespark]

Well, I'm learning from the Grand Master and, let's face it, you gotta start somewhere...

 

[ColJack]

from what i can see there are 3 reds going into breaker 2 and 3 or 4 ( can't quite tell ) into breaker 3..

might be a cross connected ring installed by a numpty..

effectively feeding 64 amps to the ring... ( 32 down each leg..)

 

[securespark]

There is a spur off each ring.

Why assume cross connection just because there are three conductors?

 

[ColJack]

if you can run it all the way back to the board why not put it in it's own breaker?

it's because there are 2 with 3 in each.. so i thought it MIGHT be one leg from the ring into each ..
not my first thought but a posibility to rule out because of the fault..