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Wiring 110v with 18/2 ok?

  1. Jul 14, 2012 #1
    I'm new to projects requiring high voltage, but I need to wire 110v to an SSR controlling a device that pulls 2 amps and all I can find in my shop is some 18/2 doorbell wire. Is this safe to use?
     
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  3. Jul 14, 2012 #2

    Averagesupernova

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    18 gauge wire is safe to use at low currents. It would be recommended to fuse it though. BUT, doorbell wire is not a safe option at 120 volts. Most likely it is not intended for use above 48 volts.
     
  4. Jul 14, 2012 #3
    Thanks for the response Averagesupernova! I looked it up before I asked the question but the wire seemed too flimsy to me. I used the chart at http://www.powerstream.com/Wire_Size.htm which rated 18 gage at 2.3 amps. If I'm using insulated solid copper core wire, how do I determine the proper gage?
     
  5. Jul 15, 2012 #4

    psparky

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    When wiring in factories, we don't use anything smaller than 14 gauge for 120 volts and when wiring for 480 volt we don't use anything smaller than 12 gauge. 120 volt wiring is typically rated for up to 600 volts I believe.

    Maximum fuse/breaker size for 14 guage is 15 amps.

    Maximum fuse/breaker size for 12 guage is 20 amps.

    Using too big of a wire never hurts, especially for a short run and small application like yours. The factories use the bigger wires for the same reason you mentioned...the smaller wires are too flimsy.

    Order some real wire online or go to your local hardware store. A 3 or 4 amp fuse will likely work for your application, or whatever the specs say on your controller. 15 amp breaker will protect your 14 guage wire.....the 3 or 4 amp fuse will protect your controller.
     
    Last edited: Jul 15, 2012
  6. Jul 15, 2012 #5

    Averagesupernova

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    That must have been what the previous idiot homeowner thought when he made an attempt at wiring in my garage. What is the sense of running #10 wires to ceiling lights? The larger the wires, the more difficult they are to handle, less room in boxes, etc. It amuses me when I see people doing a wiring project and they are going to 'do a really good job' and while they have good intentions they end up with crappy work.
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    Psparky, I realize you were not referring to the same thing I am and agree that when it is sensible it is better to be a size larger. It is likely that in this case the OP has enough room to use #16.
     
  7. Jul 16, 2012 #6

    psparky

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    Understood. Just saying these are the min sizes in certain factories for 120 volt wiring.
    Having #10 wiring for lighting would piss me off too in a residential home.

    I sometimes have to run #10 wire in factory lighting and sometimes even #8 when the lights are 500 feet away from the panels to avoid voltage drop. In rare cases I've had to use #4 wiring for lighting to avoid voltage drop....but this was for outside parking lights that were over a thousand feet from the panel!!!!
     
  8. Jul 16, 2012 #7

    berkeman

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    You must install the wiring according to your local building codes, and you must have it insptected by your city's building inspectors. In general, all electrical additions need to comply with local building codes, and be signed off by the inspectors.
     
  9. Jul 16, 2012 #8

    Averagesupernova

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    Hmmmm. Think of all the cool things you could fit in a garage large enough to justify #10 or larger wire feeding a lighting sub-panel. :)
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    Iambo, what does your project involve? Is this SSR going into a box that plugs into the wall? Being replaced in existing equipment? I'd like to know more.
     
  10. Jul 16, 2012 #9
    Hey guys, thanks for the assistance.

    berkeman, I don't think I will need building inspectors to sign off on this project, but thanks for the advice.

    Averagesupernova, my thoughts are to make a power cord that plugs into the wall, which routes to a PID and has one wire tied to the controlled device and one to the HV side of the SSR. The PID out will connect to the SSR for the signal and the controlled device connects to the HV side of the SSR.
     
  11. Jul 16, 2012 #10

    psparky

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    Cool. Run at least #16 to the outlet and at least #16 in your cord. Woo hoo!
     
  12. Jul 16, 2012 #11

    MATLABdude

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    As Average Supernova alluded to, you should check the jacket and make sure that the insulation can withstand 120V AC (that's 170V pk). You'll probably need a magnifying glass since the writing tends to be a little hard to read (but it should say on the cable jacket).
     
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