"jacob" wrote in message
m...
What size flex 3 metres long for a 2.2kw 3 phase combi woodwork
snipped
Taking all that into account, you're talking about a supply of 16 mm on each
conductor
for the lengths you're talking about, and you may also have to double the neutral
to
take the start up load until the motors are all running to speed.

With that supply it will allow you to run lighting and a few sockets from it as
well.
6kw only occasionally likely, and simultaneous start-up of all
machines very unlikely. Separate single phase circuit for lights and
sockets. So 16mm sounds excessive to me. 10mm perhaps?


thanks for info

Jacob

If you can be sure that the machines are going to be running individually from each
other, then you might be able to run the supply in 10 mm csa' but if you are going to
have one machine running on its own, then start another machine, then turn a heater
on. Your talking about un-plugging one machine before you plug another one in to be
sure that you're not going to overload the supply. Three phase has an awful
reputation of kicking you in the ass if you don't get it right first time, remember.

Any imbalance on the loadings of the three phase conductors causes heat, this heat
creates further imbalance, this further imbalance creates more heat, and so the cycle
continues. The start-up ampage of some three phase quick start motors can jump to
nearly five or six time the running ampage, so if one machine is under strain loading
taking a slightly higher ampage to do its work, then you start another machine with a
quick start motor, the ampage across the supply is huge.

Even if the load is for a few seconds at a time, it causes improperly sized conductors
to degrade very quickly, so it's best to err on the safe side of caution when you're
dealing with phased supplies. Believe me on this, I've been through it many times
with industrial installations.