12 amp wire size

[Henry]

I was wondering what cable size to use for wiring a 125V 12 amp fan that is

100 feet away from the breaker panel.

Thanks.

[Rich]

Rich

[Jeff Wisnia]

You should be able to use 14 gauge wire.

It'll drop about 4 volts at 12 amps over that length, but that shouldn't worry a fan much.

HTH,

Jeff

[Toller]

You could use #14, but there will be a lot of VD at startup, which won't be too good for the fan. #12 isn't all that much more expensive.

[dpb]

How did you determine that, and how much, specifically, are you thinking is "a lot" for a fractional hp fan motor???

That's true, certainly, and I have pretty much quit using 14, but if it's a dedicated circuit I don't think there's a chance in the world the difference would make any practical difference at all.

If, otoh, there's a chance of wanting something else, that would necessitate it in all likelihood.

--

[Meat Plow]

Not to nitpick but wouldn't a motor drawing 12 running amps (if the OP is correct) be in the realm of a couple hp? If I recall my 5 hp compressor motor draws around 12.

[Chris Lewis]

Not at 120V it don't. A "true" 5HP motor will draw somewhere around 40A on 120V, or 20A on 240V. (On motors >= 1HP, count on approximately

900-1000W/HP because of inefficiencies. Yes, I know, the exact conversion is 746W/HP, but no motor is 100% efficient)

At 120V, a standard 12A motor is probably between 3/4 and 1HP, tho possibly as low as 1/2HP. Not lower unless it's a real lousy or poorly spec'd motor. (Serious fan in any case...)

A 12A motor can draw well over three (or even five) times that much during startup. 12V or more drop (assuming the previous math was right) at 100'. That's a significant amount, and will significantly prolong startup and produce more heat, and ultimately shorten the fan motor's lifetime. Perhaps by not much, but perhaps by quite a bit.

This is a good place to go up a wire size. It's cheap.

[Jeff Wisnia]

You're correct about that, and using 12 gauge might be a wise investment.

Currently Lowes' price for 100 ft of 14 gauge is $36.00 vs. $52.50 for

12 gauge.

Jeff

[Meat Plow]

I used to work with Baldor repulsion/induction motors in the oilfield. There were all 240v, 15 hp. If memory serves, on the well upstroke they drew around 30 amps and otherwise around 18.

[Toller]

Don't know who you are; I have you blocked for the stupid things you have said in the past. For good reason, here is one more!

12a is not a fractional hp motor. Don't you even bother to read the posts?

[Edwin Pawlowski]

Borderline on a 15A circuit. 12 ga. would be better. 20 A breaker

[Steve Barker]

12/2 on a 20a breaker will more than suffice.

[Steve Barker]

52.50? that sounds like a 200' price to me.

[<kjpro]

Ever read the NEC for voltage drop allowances?

[Doug Miller]

Priced copper wire recently?

[Jeff Wisnia]

Jeff

[Jeff Wisnia]

Not recently, but if I advised something which wouldn&#39;t meet code then I apologize and stand corrected.

I just figured that a 4 volt drop would still furnish a fan motor with sufficient power to do its thing.

Jeff

[kool]

[Chris Lewis]

According to Meat Plow :

240V at 30A is 7200W, which means that during the upstroke those motors were delivering somewhere around 6-8 HP. Conservative motor selection, given that weather/rig conditions etc could cause the motor to need more.

It would have been interesting to compare that with the motor plate ratings, or know what size the fuses/breakers were.

[gfretwell]

They lie. Campbell Hausfeld lost a class axction suit over it. I ended up with a sheet metal nibbler out of it.