On 27/03/2015 09:28, Tim Watts wrote:
On 26/03/15 23:32, Nightjar "cpb"@ wrote:
On 26/03/2015 21:37, ARW wrote:
"Nightjar .me.uk" "cpb"@ insert my surname here wrote in message
...
On 26/03/2015 08:50, Jethro_uk wrote:
On Thu, 26 Mar 2015 07:56:48 +0000, Nightjar "cpb"@ wrote:

We used to remove fuses and pocket them.

Difficult if you have circuit breakers

Aren't all circuit breakers removable ? Our (domestic) ones are.
Surely
they're meant to be replaceable ?


On the distribution boards in my factories, that would have involved
turning off the three-phase supply to the entire factory, which would
allow the front cover to be removed. That would give access to the
screws holding the circuit breakers in place and then they could be
removed. It is not something you would do to permit safe working on a
particular machine.

In any case, all industrial equipment should have a local method of
isolation and those can always be padlocked in the off position. You
shouldn't really need more than that, possible with the multiple
padlock devices Tim Watts describes if more than one person might be
working on the protected equipment at one time.

Why would all the factory have to be powered down? Did your DBs not have
their own main switch?

Most of the factories only needed one distribution board; much of the
work was hand work or used single phase equipment. One of them needed
two boards, so there only about half the factory would have needed to be
shut down.



Most DB boards I've seen in industrial settings could have the door
locked and the key removed - so even if the breaker cannot easily be
locked off for one circuit, it could be switched off and the DB door
locked with a warning sticker.

These were just pull to open. The only reason this bit of the thread
arose at all is because Harry mentioned pulling fuses and I pointed out
that was not particularly easy with circuit breakers. In any case, some
circuit breakers served more than one machine, so it wouldn't have been
an ideal solution. I simply had local isolators that could be padlocked
off and safety procedures that I always applied, like standing on a
piece of switchboard matting when working on electrical circuits. That
proved to be very useful in a newly acquired factory which did have
fuses which were in my pocket, when I was working on terminals on a
three-phase supply, which I later discovered were fed from two different
sources and had been live all the time.


--
Colin Bignell