Electricians? Weird problem!!!!!

[Fuddy1952]

I installed a fan and a light in the horse stable. Fan is 120v, 5.5 amp. Light is 35 watt (300watt equ) LED. To test everything I used a 50 ft 14 gauge extension cord, wires just pushed in socket. Worked fine, and I let fan run an hour or so, even cycled it a few times.
Today I wired in conduit. Square D box, out of 20 amp breaker (of course on black hot) which goes up to a simple ceiling light above tack room, a 60w bulb with socket. Pull string switch. Nothing else on the circuit. Convenient and not far from fan so that's where I picked up power. All wire, panel box to there...that to switches is 12-2.
In double switch box 120v in (12-2), then out with 12-3 up to fan & light. I have all bare grounds tied together, white neutrals together. Before I put switches in, I just touched red going to light to black hot...light works perfectly. Then I tried hot to black fan hot...fan motor hummed & tiny bit smoke came out!!!!!
I checked, blade turns free, I double checked wiring. With Fluke meter 124.5vac no load, same with light on...108.4vac touching fan wire! (I just try it a second). It sparks when I touch it, fan never moves.
If it worked with 14ga extension cord...wouldn't it work with 12 ga?
From upstairs light up to fan is a little less than 50 feet, probably 20 feet there to panel box. The circuit breaker never trips.
Any ideas much appreciated!!!!!

 

[kenmac]

I'm no electrician, but have wired many lights and plugs. I really don't see anything wrong with your wire diagram.
12/2 wire should make no difference. on what you are running. I doubt that fan and light pull 20 A
Have you checked voltage at the fan hot wire with fan disconnected ?

Perhaps something is shorted in the fan motor

 

[jaxs]

This has nothing to do with wire guage or breaker amps,something is crosswired or fan is kaputt. If I was taking bets I'd give odds on sub-panel not properly wired for ground/earth/green. Make sure you follow code for ground and neutral bar separation at sub-panel. It doesn't make a lick of sense but has been proven voltage can go from black to bare then to white unless bars are isolated by removing screw.

 

[tallyho8]

Use a voltmeter and check your voltage from your black wire to the white wire and from the red wire to the white wire and see if you have 220 volts instead of 110. If you do your fan is toast because you let the smoke out.

 

[Fuddy1952]

Use a voltmeter and check your voltage from your black wire to the white wire and from the red wire to the white wire and see if you have 220 volts instead of 110. If you do your fan is toast because you let the smoke out.

I'll make lots of checks tomorrow. Thanks all!

 

[grsthegreat]

If you are only feeding this with a single breaker, and a single black hot, you can't possibly have 240 v. Is the fan known good, or was it old.

your schematic looks fine.

 

[Midniteoyl]

If you applied power and tried to start the fan when it's switch was in Low (or even Med), you probabaly 'locked' the fan motor and it overheated. There is a reason fans always have High as the first setting and have to go through it to start the fan.

Impeadence of the motor coils mean there is voltage drop across it so will read lower voltage with the meter.

Make sure the fan is in High setting and rotate the blades before adding power, if it spins up, the fan is still good and you know your problem. If not, then most likely fan is now blown and you know what not to do.

 

[Fuddy1952]

If you applied power and tried to start the fan when it's switch was in Low (or even Med), you probabaly 'locked' the fan motor and it overheated. There is a reason fans always have High as the first setting and have to go through it to start the fan.

Impeadence of the motor coils mean there is voltage drop across it so will read lower voltage with the meter.

Make sure the fan is in High setting and rotate the blades before adding power, if it spins up, the fan is still good and you know your problem. If not, then most likely fan is now blown and you know what not to do.

Fan doesn't have speed settings, just a GE 120v motor...(I'm guessing 3/4?hp) capacitor start.

 

[Midniteoyl]

Fan doesn't have speed settings, just a GE 120v motor...(I'm guessing 3/4?hp) capacitor start.

OK. Was thinking it was more like a ceiling fan.. Have you checked the cap then? Could still start the blades by hand and try to check if motor itself is still good.

 

[DarkBlack]

“If you applied power and tried to start the fan when it's switch was in Low (or even Med), you probabaly 'locked' the fan motor and it overheated. There is a reason fans always have High as the first setting and have to go through it to start the fan.”

I’ve never seen, or heard of a 3 speed fan, that was designed so it would burn up, if started in low or medium speed