Shared air and electric line

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curtis cutter
Posts: 388
Joined: Fri May 18, 2012 11:46 pm
Location: Curtis, WA

Re: Shared air and electric line

Post by curtis cutter » Mon Jun 03, 2019 4:55 pm

jcfx wrote:
Mon Jun 03, 2019 4:32 pm
curtis cutter wrote:
Mon Jun 03, 2019 12:29 am
How many amps do you think you will need to see at the end of the run?
20 amps max. for just the welder if I'm reading rating plate on the MP210 welder correctly.
How many feet from your source to your load?
Gregg
Just let go of it, it will eventually unplug itself.

jcfx
Posts: 448
Joined: Sun Aug 09, 2009 1:24 pm
Location: NY

Re: Shared air and electric line

Post by jcfx » Mon Jun 03, 2019 6:52 pm

Best guess, 120 ft ?

curtis cutter
Posts: 388
Joined: Fri May 18, 2012 11:46 pm
Location: Curtis, WA

Re: Shared air and electric line

Post by curtis cutter » Mon Jun 03, 2019 10:49 pm

Below is a calculator. I personally would shoot for a 3% voltage drop or less. For a test, run Copper 10 AWG wire and see the results then try 12 AWG. Although 12 AWG will handle 20 amps, it has a cost for trying to push it through the wire and that is more voltage drop than you may wish.

https://www.calculator.net/voltage-drop ... &x=62&y=16
Gregg
Just let go of it, it will eventually unplug itself.

John Hasler
Posts: 1243
Joined: Tue Dec 06, 2016 4:05 pm
Location: Elmwood, Wisconsin

Re: Shared air and electric line

Post by John Hasler » Tue Jun 04, 2019 12:55 pm

Your bx has to be large enough (i.e., small enough AWG) to be protected by the upstream breaker. It also should be large enough to comply with the NEC recommended 3% maximum voltage drop limit at the rated current of the upstream breaker.

I'd put bushings on the ends of the conduit (you'll want these to protect your air line anyway) and treat it as a really small tunnel.

BTW is there any chance of the conduit filling with water? If so don't use unjacketed bx.

jcfx
Posts: 448
Joined: Sun Aug 09, 2009 1:24 pm
Location: NY

Re: Shared air and electric line

Post by jcfx » Thu Jun 06, 2019 5:47 pm

Curtis, John, Thanks for the advice, that calculator is handy,
I don't think there's any chance that the conduit will fill with water.

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