- Reaction score
- 1,556
A weird one but here we go.
I was asked to add a new 3ph circuit into an existing 6 way 3 phase dorma smith D.B. The board had to remain up and running ( not quite meeting the EAWR I know) so with the singles now in all I had to do was slide the 3ph breaker in the spare space 6L1-6L3.... This was where the explosion happened.
Everything was clear of the terminals, the new breaker was, just in case, switched off. As I pushed it onto the bare copper something caused 2 phases to come together resulting in me with temporary blindness, my hand completely black and ending up with me on the floor on the other side of the switch room.
The board and myself were in a bad way but once I was ok I began looking for explanations. The breaker wasn't bridged out which I had expected and nothing obvious stood out in the smoking D.B.
My foreman couldn't explain it either but he had heard of it happening before because of the air in a live board becoming 'ionized' therefore becoming conductive. Any spark caused by the breaker touching the busbar would have been enough to jump through the now conductive ionised air and bridge out to the next phase.
Has anyone else heard or come across this as I'm struggling to find a possible cause
Mark
Stupidity on your part for doing it live in the first place, if you worked for the company I work for you would have been sacked on the spot.
EAWR 14 comes to mind, if this was reported to the HSE expect to be making a visit to the man/lady with a white wig and black gown.