Bang

[opps]

Swung by my mum's yesterday. My stepfather mentioned that the pull cord isolator for the shower had stopped working. He had loosened the screws for the fitting. I had my screwdriver in my pocket- the type that has a green and red LED and can show current via induction. I pushed the slotted head into the live on the left... and BANG.



You can see the arching on the screwhead (not there previously).

I am at a loss as to why it happened. The fitting is plastic. I cannot see how I bridged anything. It tripped both the RCD and the MCB. I didn't notice any water in the ceiling fitting.

Very odd.

 

[pete01]

I bet the earth plate runs around straight past the live terminals you must of touched both by mistake.

 

[AdrianUK]

^^^^^ What he said!

 

[opps]

Yup you were both correct.

Turns out that the earth plate is pretty much flush with the edge of the plastic body.



No idea why there is evidence of a second arc on the left hand side.

Thanks for your sage diagnosis gents.

 

[Adam_151]

I can remember when I was just qualified, I was swapping over some pieces of fixed equipment connected to RCD spurs throughout a building, one of them was faulty and wouldn't trip, wholesaler right around the corner, so grabbed a new one, but dis board was devoid of labeling and as the RCD accessory had just been tapped off some other circuit so only had one cable in the supply terminals, I perhaps thought I was being clever by just swapping it live, well no, because I hadn't seen where the earthed metal between the two screw fixings was and I of course then, knew exactly which breaker supplied it!

 

[chivers67]

Judging by the charring on the blue cable the Neutral on that circuit looks like it was loose too. I always prefer Crabtree isolators, they look a bit big though.

 

[333rocky333]

Just wondering why you stuck the screwdriver in the live
Does that screwdriver not, as you mentioned show its live via inductance

 

[opps]

Yeah, the neutral was loose. I cut it back before fitting it.

Just wondering why you stuck the screwdriver in the live
Does that screwdriver not, as you mentioned show its live via inductance

Good question. I just wanted to see if the screws were tight. Additionally, the inductance part of the screwdriver does give false positives. The inductance makes the green LED glow. Direct contact makes the red LED glow.