A cautionery tale regarding electrical work

[adam2]

An electrician working in a department store recently suffered a serious accident, it would be incorrect to name names, but I felt that the circumstances might be worth repeating.

 

A wall mounted 13 amp socket had been damaged and required replacement.

The MCB board had no list to identify the correct circuit, therefore the electrician turned off the main isolator feeding the board, and applied a padlock to prevent anyone turning it on.

 

He then tested the damaged socket and proved it dead, whilst connecting the replacement he received a nasty electric shock, which could well have been fatal (wet suroundings due to a plumbing fault)

Checks at hospital showed a fractured skull, presumably as a result of the shock causing his head to impact on something.

 

Investigation showed that the socket in question was not supplied from the locked off board but from an alternative source.

The supply was controlled via a contactor and a photocell, darkness fell during the work thus causing the circuit to be rendered live.

 

Shows the importance of ensuring that the correct circuit has been isolated, proving dead is important, but not on its own sufficient as this case shows.

The wearing of a hard hat might well have prevented the fractured skull (though it would not have prevented the shock)

Wearing a hard hat is not normally considered a requirement for minor electrical work, at low level, in an occupied building.

The man is still off work, but expected to make a full recovery.

 

Although this is not theatre related, one could see a similar accident occoring in a theatre or similar venue.

[KevinE]

The person who fitted the photocell should have marked the sockets with a permanent sign stating where they're fed from especially if they're expected to go 'live' without warning. It's the same (but for different reasons) with air compressors and hoists and other accessible remote controlled machinery that may cause a hazard due to unexpected startup. The IEE has a regulation stating that installations should be designed to minismise risk to persons during maintenance or alteration..someone will no doubt quote the reg number.

 

Most thoughtful industrial installations these days have electrical outlets and lightswitches dymo-marked with some sort of code saying where everything is fed from; what feeds that; and so on back to the main dist or local sub, and this type of thing would have helped.

 

Of course the electrician should have made sure he'd switched off the correct board but it's this type of thing that will catch us out occasionally.

 

RS used to do a plug-in bleeper box which stayed silent on power-up conditions and started beeping when power was lost, as an aid to isolating the correct circuit!

 

I came across a similar situation in a pub where I isolated a lighting circuit to do some work on it, only to find that some amateur had 'borrowed' a neutral from the circuit for another circuit fed from a different dist board!