On Aug 10, 10:19 pm, Dave Osborne wrote:

1. Refuse to work on the equipment at all and advise anybody else who
may work on the equipment that they take their life in their hands. Make
it a big issue that everybody knows about, so nobody can ignore it,
especially management. You're under no obligation to put your life at
risk in this way. A lack of significant action by management would
constitute constructive dismissal if you felt you had to leave your job
to avoid dying.

Well I'm glad everyone here seems to think this is a serious matter.
The person who ignored the sign and turned the power on was telling
everybody at the lunch table that the electrician had over-reacted.
I managed to avoid saying what I thought about that.
I have also managed to avoid emailing my boss about this appalling
incident. I hope I remember everything I want to say to my boss
tomorrow.

Finally, if this switch needs to be operated morning and night and
dozens of people have they key, why is it locked at all?

If the switch was not locked it could be turned on or off by the
public.
In theory only intelligent well-trained people have a key. I now know
that to be false.