Switching 220v?

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  #1  
Old 09-06-04, 03:56 PM
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Switching 220v?

I want to put a switch with a pilot by the door of my shop to kill the power to my compressor which is outside at the back. It's 220v 16a. What would be the best way to do this? I'd like to use a relay or something so I don't have all that voltage running all over the place. It has a magnetic starter which I could hook to a switch to but it would only cut off at the pressure switch. I want to kill all the power running to it.
Thanks.
 
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  #2  
Old 09-06-04, 06:51 PM
sjr
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A double-pole switch would do what you want. Something like the Leviton 54502-2W

Not sure about getting one with a pilot light built-in, but you might be able to work in a separate indicator light in a double-gang box.
 
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Old 09-06-04, 08:12 PM
hex2k1
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Hoffman,


dont know how much experience you have but they make disconnect switches that could disconnect the power and have auxillary contacts that you can wire to a pilot light to indicate power on/off. also like sjr said they also have the regular 2 pole switches that are probably more economical and easier to install for the diy person.
just wanted to let you know about another option. if you do go with a disconnect you might want to have an electrician install it cause it could get a little more complex. if you install the 2 pole switch make sure that you get the correct rating specially if you want to use it as a starter for your compressor as opposed to power disconnect only
 
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Old 09-13-04, 07:41 PM
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Thanks. I have a dpdt switch rated at 20 amps. The compressor has a magnetic starter which I guess does all the heavy work. Right now I just switch it with the breaker but I want a switch by the door. I was thinking about puttting a pilot light on one leg of the circuit but I really don't need it. I have a way of complicating things for the sake of being cool sometimes...
So with the switch do I just hook each leg to the two sides and connect the ground?
It'll be about a 25 ft run.
 
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Old 09-14-04, 05:41 PM
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The DP switch will have 4 terminals 2 line & 2 load.Power goes to the 2 top terminals & the load {compresor} goes to the bottom 2.
 
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Old 09-14-04, 05:44 PM
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Leviton probably has an illuminated DP switch.All grounds go together including from the switch.
 
  #7  
Old 09-14-04, 06:02 PM
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A magnetic starter makes this situation a piece of cake to solve.

Get yourself a "control station" with two buttons; one marked "Start" and the other marked "Stop".

Also get a relay that is compatible with the "coil voltage" of the magnetic starter. The relay will need an enclosure. If the coil voltage is 120 volts (should be) then a two pole relay should be all you need.


The relay will make/break the voltage from the pressure switch to starter coil.


The relay will be wired in such a way as to "latch" itself on.

What happens is this:

The momentary "Start" button sends current to the coil of your new relay.
The relay is wired in such a way to complete the control circuit for the compressor AND to send voltage back to the new relay's coil, thereby "latching" it on.

The momentary "Stop" button is a momentary "Off" switch; I failed to mention this before, but it's wired in series with the latching circuit. So, if you press the "Stop" button, it breaks the latching current and the relay falls out.

Find yourself a very old alarm installer and he will understand what I am saying.
 
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Old 09-14-04, 06:34 PM
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hoffman,

Having a magnetic contactor gives your compressor a deluxe option.

The simplest way and one that is most commonly used on small commercial compressors is to connect a switch in series with the pressure control.
Our electrical code and possibly yours allows a control circuit to have wire sizing according to the load of the control circuit.
So in your case if this applies, which I believe it may, all you need is to run #14 - 2 conductor to a regular wall switch.
If you want to get fancy you can run 3 conductor, install a pilot light at the switch and make sure the pressure control is wired after the switch.
 
  #9  
Old 09-15-04, 06:54 PM
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Thanks for the replies. I ran #10 to a dpdt switch and then to the compressor. I guess you could say that the switch is acting as a disconnect. It's rated at 20a. Is there anything wrong with this? My friend has a big compressor with no mag. starter and he's had his wired this way for several years. I recently told him that his setup may not be cool because of potential arc-blast. My understanding is that a starter will prevent this sort of thing.
Any input?
 
  #10  
Old 09-15-04, 07:29 PM
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hoffman,

All you need is a spst switch connected to the contactor holding coil.

There would be no excessive arcing if the switch was rated for the amperage of the motor, but using a contactor increases the life of the pressure switch and wall switch contacts.
 
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