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Thread: contactor hookup help needed.

  1. #1
    Join Date
    Oct 2011
    Location
    Seattle
    Posts
    349

    contactor hookup help needed.

    I am wiring a remote switch for my 220V compressor- got an appropriate contactor and need to know the best way to get the
    120V for the coil. Do I wire in a separate 120V circuit or can you tap into one of the 220 legs from the breaker. Obviously not
    an electrician---but my best guess is I need a hot, neutral, and ground for the coil and with no neutral from the 220 circuit I will
    need a separate 120V hook up. A standard 120V outlet is handy so is it reasonable/logical to wire a plug-in cord to the coil via remote switch,
    or hard wire(a bit more work) to the contactor? I moved the compressor to an attached shed and won't be using the space for any
    other purpose than the compressor. Also I want to use a switch that illuminates when the compressor circuit is on, not just when it
    is running. Need suggestions here as well. Don't want either me or buddies using my hobby shop to forget to turn off the compressor
    when leaving. The coil has "spade"?? connectors on either side, and again best guess is hot to the coil and neutral is leg to switch and
    back to the other side of the coil. (Just thinkin'--how is the lighted lighted powered up then). Thanks for your help?? JCB

  2. #2
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    9,136
    John,

    I'm no electrician either, but I found the contactor straight-forward to wire. (I use the contactor on the dust collector, not the air compressor.) If it will help, this is the wiring diagram from ClearVue for their cyclones. L1 and L2 are the two hot wires from the 220v line.

    clearvue_wiring.jpg

    The contactor should be in an electrical box of course. If you plan to mount your 110v switch in that same box you can run a flexible cord into a that box if you use the proper connector where it enters. I understand you can't run any electrical line into or through a wall unless it is protected by conduit. If you use a metal boxes, ground them too.

    If your 220 has four wires, hot/hot/neutral/ground, you can use one leg to power the switch that powers the contactor. However, I prefer to use a separate 110v circuit. I have my DC and compressor in an insulated closet to cut down on the sound. I decided to add a sub-panel for110v. This gave me a separate circuit for the circuit that powers the contactor plus lights and extra 110v outlet for the room. My DC uses a wireless remote controller that is in the main shop so this powers that and switches in both locations to disable the DC. I put the DC contactor in it's own box. I also added a subpanel to give me separate breakers for the DC and compressor in the closet. My remote controller and DC bin sensor and alarm is outside the closet in the main shop.

    DC_electrical_closet.jpg DC_electrical_shop_s.jpg

    BTW, one reason I wired this way was to avoid a rat's nest of wiring for dust collector installations that use a wireless remote and a bin-full sensor with an alarm. When I asked ClearVue for clarification on some point, they sent me these photos saying this was "typical":

    DC-Controls_typical_with_text.jpg

    As I said, I'm no electrician but I understand you have to provide an electrical disconnect such as a breaker, switch, or plug visible and accessible from the equipment location. This would need to be in the external shed. If the equipment is directly wired to the contactor, the disconnect has to disconnect the power from the contactor, not just the controller. One note: it's my understanding that a switch that turns the motor on and off directly needs to be rated for the motor load. I use this one for 5hp motors: https://www.amazon.com/gp/product/B002MPQ51O Note that there are 220v switches with sufficient amperage rating that are NOT rated for use as motor disconnects.

    You can use a standard light switch for the 110v. There are switches with built-in pilot lights but they are not very bright. But if you want something that is easier to see, you can wire in a standard light socket and drive it from the 110v switch that controls the contactor. Then you can use any kind of light bulb you want. I don't use an indicator light on the compressor but my 220v disconnect switch mounted in the main shop where it is easily visible when I close up and I'm the only one using the shop.

    That's all I know (or think I know - I'm sure someone will speak up if I'm off base). As always, if the least bit uncomfortable with any wiring hire an electrician.

    JKJ

    Quote Originally Posted by John C Bush View Post
    I am wiring a remote switch for my 220V compressor- got an appropriate contactor and need to know the best way to get the
    120V for the coil. Do I wire in a separate 120V circuit or can you tap into one of the 220 legs from the breaker. Obviously not
    an electrician---but my best guess is I need a hot, neutral, and ground for the coil and with no neutral from the 220 circuit I will
    need a separate 120V hook up. A standard 120V outlet is handy so is it reasonable/logical to wire a plug-in cord to the coil via remote switch,
    or hard wire(a bit more work) to the contactor? I moved the compressor to an attached shed and won't be using the space for any
    other purpose than the compressor. Also I want to use a switch that illuminates when the compressor circuit is on, not just when it
    is running. Need suggestions here as well. Don't want either me or buddies using my hobby shop to forget to turn off the compressor
    when leaving. The coil has "spade"?? connectors on either side, and again best guess is hot to the coil and neutral is leg to switch and
    back to the other side of the coil. (Just thinkin'--how is the lighted lighted powered up then). Thanks for your help?? JCB
    Last edited by John K Jordan; 03-25-2020 at 7:42 AM.

  3. #3
    Join Date
    Oct 2011
    Location
    Seattle
    Posts
    349
    Thanks John,
    Just wondering --where's all the sawdust???-. That's an efficient looking installation. I am assuming the 120V hot and switched neutral legs connect
    to the spade connectors on either side of the coil--so--I will need a four conductor wire running to the switch to have a neutral for the "system on "
    light, whether a separate light socket or a lighted switch. We have a state mandated shut down starting tomorrow so I need to do all my shopping
    today!! Thanks JCB

  4. #4
    Join Date
    Aug 2015
    Location
    N. Texas
    Posts
    1,492
    Quote Originally Posted by John K Jordan View Post
    ... this is the wiring diagram from ClearVue for their cyclones. L1 and L2 are the two hot wires from the 220v line.

    clearvue_wiring.jpg

    ...
    John B.
    If I understand your plan correctly, then John J.'s diagram will get you where you want to go. The coil signal 'enters' from the top and can be sourced from a different CB vs. the 220V. You can put 2 std wall switches in series in the 110V line: one in the shop (or use a lighted version); and a second within sight of the contactor. Either can kill the signal to the coil. The first will allow normal activation; the second lets you kill the 110V signal locally to allow safe servicing.

    To be safe(r), I'd put a local disconnect (aka knife switch) on the 220V supply just ahead of the contactor. This gives you another means besides a presumably distant, out-of-sight CB, to kill the 220V supply for servicing.

    BE AWARE - and label the contactor - that there are 2 voltage sources into the contactor!! BOTH must be OFF to prevent you from letting the magic smoke out of your fingers.

    Adder:
    Just occurred to me, you can handle the 'local' disconnect/safety in one device: Ditch the 2nd light switch I reference above and get a 3-pole knife switch; break the 220V power feed across 2 of the poles, and break the 110V coil signal across the 3rd pole. Then the knife switch kills ALL power to the contactor. (The coil signal is still controlled via the 1st switch in the shop.)
    Last edited by Malcolm McLeod; 03-25-2020 at 11:57 AM.
    Molann an obair an saor.

    If Heaven ain't alot like Texas, I don't wanna go. - Hank Jr.

  5. #5
    Join Date
    Sep 2016
    Location
    Modesto, CA, USA
    Posts
    3,630
    Or buy a new 240 volt coil or a transformer to make 120. it is probably cheaper to buy a complete used contactor on ebay then to buy a new coil. Check ebay for replacement coils as they have quite a few at most times.
    Bil lD

  6. #6
    Join Date
    Feb 2008
    Location
    E TN, near Knoxville
    Posts
    9,136
    Quote Originally Posted by John C Bush View Post
    Thanks John,
    Just wondering --where's all the sawdust???-. ...
    Ha! I spent so much time building the shop (from clearing the ground to wiring up the DC) that I didn't get to make much sawdust until later. There is plenty now, but fortunately most goes in the bins. The 5hp Clearvue is an amazing suction device.

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