I work for a large temperature controls company and we use the contactors
you are discussing all of the time. What you are trying to do is set up an
electrical circuit where you have multiple switches wired all in series. The
voltage used to power the contactor is supplied by a transformer. It steps
the voltage down from 120 VAC to 24 VAC. One side of the transformer (the
common) is wired to the common side of the transformer, the other is wired
through the normally closed switches, one after another, to the other side
of the contactor coil. If any one switch is hit, the circuit will open
preventing the contractor from being powered, killing the power to your
power tools.

Depending on your local codes, you can mount a 24VAC transformer at the
circuit breaker panel and route the wires through the wall to the switches,
without conduit. The 24VAC transformer should be sized to handle the
contactor while not exceeding a rating of 100VA (about 4 amps). That will
meet the requirements for class 2 wiring, and can normally be run with
thermostat wire. A 40VA, 24 VAC transformer will more than do the job for
you assuming a typical 30 or 40 amp contactor.

"robdingnagian1" wrote in message
oups.com...

Brett A. Thomas wrote:
Ok, almost got it then, I think. Thank you, you've saved me many
hours!

So, I get three or four button and contactor blocks, like this one:



http://web4.automationdirect.com/adc/Shopping/Catalog/Pushbuttons_-z-_Switches_-z-_Indicators/Eaton_Cutler-Hammer_22mm_(E22_Series)/Emergency_Stop_-z-_Mushroom_Pushbuttons_-a-_Stations/E22JLB2N8B

I then connect them to a 40 amp, 24 volt contactor, such as this 2
pole
model:

http://store.yahoo.com/waterheater/c2con40amp2p.html

I also connect one side of the contactor to a 30 amp/220 volt circuit
on
my existing subpanel, and the other side to the input of the new
subpanel.

Assuming all this is correct, I only have one question - does the
contactor step the 220 down to 24v for the buttons? Or do I need a
seperate transformer to do that? Something like this, maybe?



http://www.surpluscenter.com/item.as...tname=electric

Thanks again!

-BAT


You might want to consider some start buttons to turn it all back on.
They make pushbutton stations that have large "panic" buttons for the
stop button and also include a start. Also, check your codes as to what
gauge wire is going to need to feed your subpanel. See if they will
allow your particular setup.

I have some of those definite purpose contactors and didn't really know
a use for them. Now you have me thinking. I'm not plannning what you're
planning. But, the noggin is smoking. As I've never used one and don't
know their proper wiring, I do have this question. Can several
pushbutton stations operate the same contactor or would there need to
be a series of contactors? I've only wired magnetic starters and one
per machine. I haven't tried to feed a subpanel with them.

I look forward to seeing how this thread progresses when some of the
electrician types get home from work.
Eric T. in MN

ps. Brett, where are you located?