"Robert Bonomi" wrote in message
ervers.com...

Next, what all might be running at one time, _worst_case_.
obviously the lights, plus the air conditioning. The compressor
can be 'trusted' to kick in at 'the worst possible time'.
Add in the dust collector, and the the biggest hog power tool.
Wups! what if there are _two_ people in the shop. might have
two tools running. That puts the theoretical total draw into
the 100A range. which looks like 3 ga wire.

Robert, I think your technical description is accurate. However, there is
one very important key point to remember. The current ratings you use are
full load amps. A table saw cutting 3/4" redwood doesn't draw anywhere near
the current when cutting 2" hard maple. A 2hp and 5 hp motor will draw
approximately the same current when subjected to the same loads. An air
compressor does not draw full load when it first kicks in (excluding initial
startup inrush). The current climbs as the pressure in the tank approaches
maximum. A drill press is rarely used anywhere near full load, unless
swinging a large forstner in hard wood.

The rather dim scenario you painted is highly unlikely to occur, in my
opinion. But it does point out the need to consider useage patterns and
simultaneous loads. Actually this works in favor of most users. Otherwise,
they would be tripping circuit breakers constantly.

Bob