On Sat, 28 Jul 2007 10:15:04 +1000, Jordan
wrote:

Thanks guys, I'm getting the picture.
It's just the installation cost I'm concerned about.
As a hobby shop, I may only have a couple of possible 3phase machines.

The equipment is more expensive, but not solid gold expensive - 600V
Class gear (277Y/480V) is roughly double the same stuff for 300V
service. If you scrounge a little you can find it used, there are
brokers who resell used gear, and they might have a 200A 277Y/480V
service section for cheap because most of their sales would be of the
bigger 400A and 600A sections.

Do ask the power company about the rates you'll pay for your various
options, because they can have a profound effect on your decision that
lasts for years - you only pay once for the gear and the install.

Commercial power rates are normally higher than residential, and it
often has a "Time Of Use" factor - the KWH rate is cheap at night,
roughly the same as residential rates in the mornings and evenings,
but 10 AM or Noon to 5 PM "Peak Time" can be double or triple the
residential rates - and that'll kill you...

They're trying to get heavy industries to start work earlier and
shift their peak loads to the off-peak hours. Run the kiln and the
heat-treat oven overnight, do the welding and machining from 4 AM to
Noon. Leave the afternoon capacity available for air conditioners.

If you think you'll ever end up with any 480V equipment, get a
277V/480V Wye 4-wire system. You can easily run a transformer to drop
the 480V down to whatever you want, but boosting from 208V or 240V up
to 480V is a problem - you need double the amps and you run out of
240V panel feed real fast.

Having the neutral (4-wire Wye system) is important, because that
gives you both the 480V and 277V options, and a lot of industrial
high-bay lighting gear is 277V - one 20A circuit can light up a whole
lot of space for cheap.

(But you want the fixtures to have individual fuses in them so they
self-isolate, because with one lighting circuit having one bad ballast
trip the breaker knocks out all the lights.)

-- Bruce --