"The Medway Handyman" wrote in message
. uk...
Working for a regular customer in an industrial unit today & he asked me
to check why a 230v socket wasn't working. Socket tester showed no live
but all wires were properly in place. No mcb tripped on the panel.

Found another socket on an adjacent wall not working either, but sockets
in between them work fine.

There is metal trunking running all around the unit just over head height
& conduit running down to sockets. Since its a cash & carry type place I
couldn't get to a lot of the sockets to check them because of the display
shelving. Must be at least 20 double sockets though judging by the
conduit drops.

Big scary cabinet on wall with stickers saying 415v and 100 amps - not
going anywhere near that!

I have accidentally worked on live 415v, but putting down an insulating
floor mat first and automatically making sure I never touched two different
metal objects at the same time, meant I didn't notice until I traced the
cables later.

I'm guessing, but are industrial units wired up with some 230v sockets
running from each of the three phases? Is this to spread the load out?

Seems logical to me if some sockets are fine & others not. Is every third
socket from phase A, every forth socket from B etc?

Maybe, maybe not. It was always considered good practice to keep at least 6
feet between sockets on different phases. If they are closer, they are
likely to be wired in blocks, with several adjacent sockets on one phase. If
they are widely spaced, they might be wired on alternate phases. Again, good
practice would be to mark phase colours, either with phase disks by the
socket or by sleeving the live with a phase colour.

Colin Bignell