On 10 Aug, 01:13, Matty F wrote:
Does anyone have any brilliant ideas about how to ensure the main
power switch remains off when someone is working on the wiring?

You don't use a padlock alone, you use a "lockout clamp" and then you
use multiple padlocks.

http://www.supplysideusa.com/Images/...ges/SS-003.jpg

The clamp is a simple "padlock multiplier". Rather than relying on
one padlock per lock (and everyone + dog has a key) the clamp always
leaves at least a couple of spare holes. In one of these the
electrician places their own padlock, to which only they have a key.
That way no-one else gets to remove the electrician's padlock. Bolt-
cutters are an obvious issue otherwise.

It's also bad practice to use isolators as switches. Switching one &
off every day through the isolator encourages the view that finding
the isolator locked out and turning it back on is "normal working
practice", rather than an indication that something unusual and not to
be fiddled with is happening that day.