I've been contemplating the same thing you have for quite some time. There
was a product made called the Automater by some company that has since went
out of business. You can get current sensing relays from your electrical
dealer that can be mounted in you electrical breaker box that will
accomplish what you want.

You may also wish to contemplate getting the microswitched blast gate system
from Pen State Industries. It can be bought directly from them or through
somebody like Amazon. It turns on your dust collector whenever you open a
blast gate. Works like a champ. A friend designed his own system similar to
the PSI unit. I am planning on ordering it soon. The only disadvantage is
that you have to run hook up wire to each blast gate. Not a great deal for a
mobile system that is hooked up and unhooked regularly. More of a permanent
install system.

Rick


"Nick" wrote in message
...
Hi,

I'm wiring up my shop. I have a total of 8 separate wall circuits.
One circuit is solely for the dust collector. Two of them are 220's.
The rest are simple 20 amp circuits. The lights are on completely
unrelated circuits. They will all come into the breaker box via the
bottom. I am interested in wiring them up so that whenever current is
being drawn by any of the seven, the dust collector circuit will
"sense" that a tool is on and then kick in the dust collector.
Finally, it would be nice to make it so that the dust collector
remains running for an additional 10 or 15 seconds after the tool is
shut down. I wouldn't need to have all seven circuits hooked up this
way maybe just four of the 20 amps and one of the 220's. With ample
instructions I think I can handle the job myself. I'm not that
familiar with relays but if you can point me to the parts I would need
and give me some wiring tips I should be able to do this. At first I
was just going to get one of those remote control gadgets from Penn
State or wire in a half dozen 4-way switches scattered around the room
but this solution would be neater and fully automatic.

Thanks,

Nick