Damn motor wiring

T

tattooedfreak

Steel mutilater is more like it.
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Mar 12, 2010
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Ok, here's the scoop; I have a 1hp general purpose motor, 115/230 running 13.6 a/6.9 a. I wired it for 115 to start but when I put a load on it, it trips the circuit, of course. I recently put in a sub panel running off a 40 amp breaker. I used a quad breaker with 2 single pole 15a and one double 15/240. I wired a single 15 for general purpose and the double for my motor. I rewired the motor to 240 and plugged it in, no run. I switched out the plug to a 115, rewired the motor to 115, runs fine. Switched back, nothing. Did the switch once more to 115 (in case I am cracked) runs fine. I havent tried it with a load yet, that is the next step. Switched once more to 240.. nothing. Is there something I'm missing? Im using 12/2 wire in the panel and 14/2 at the motor, is that the issue? I can't see that as it only uses 6.9 amp at 240. Please help.
 
Might be a dumb question, but are you sure you're getting 120v per leg on the 240v? I've run into bad breaker / unstripped wire before at termination.
 
Need to go pick up a cheap meter. Cost only $10-$20 and will tell you everything you will need to know about your set-up. DO you have anything else running on the 220v?? That might tell you something.
 
I'd go with what A C Richards said - maybe try something else at 240V. May be able to borrow or pick up a meter for pretty cheap, too.
 
If you've got two wires coming out of the breaker, and each are running to the motor, you should have two hot legs regardless, unless there is a breaker problem, which seems unlikely. Hell you could get two hot legs by running the hot wires off two seperate single leg breakers.

The ground and neutrals should be connecting to the panel. If you're using 12/2 wire, you should only have 3 wires, 2 hot, which will both connect to the breaker, and 1 ground which will connect to the ground bar in the panel.

You are aware that you usually have to wire the motor itself totally different right? I mean, the numerous wires from the motor have to be connected in different ways than when you're hooking a single hot leg and neutral to it. First thing, i'd triple check the wiring diagram on the motor. You'll probably have to connect some different combination of motor wires to themselves and/or each leg from the box.
 
If you are pulling 120VAC off a single 40 amp breaker, and splitting that up into the component parts to wire the motor, you are not going to get 240VAC. You will still have 120. You have to pull the power off two separate legs and use those for 220.

I am going to be blunt here and say that if you don't understand motor wiring and 120 vs 240 voltage cuicuits.....get someone who does to do it for you. You could fry a motor, start a fire, or kill yourself.

There are plenty of folks you know who will come over and do this for you for a six-pack of beer.....just give them the beer after the wiring is done :)
 
I have a 40 amp 240 outlet in my shop that was used for a kiln. I bought a pigtail to match and made a small sub panel so I could run motors or whatever without drawing off shop power. I bought a seimans panel which can use the mini breakers of which I bought 1 quad (15a 120/ 15a 240dp/ 15a 120) I also already had a single 20a. I set up the quad with one single 15 to an outlet and the double to an outlet. The 120 works fine, the 240 doesnt. After trying my original post, I rewired to 120 and connected to my grinder (a coote), it ran for about 20 seconds then shut off-tripped breaker. it is pulling 13.6a so after loss through heat, wiring etc, fair enough. I rewired to 12/2 for 20 amp and tried again. Ran for 20 sec then the motor tripped, not the breaker. Back to the quad; if Im getting power at the single, it should automatically have power at the double since they are all connected so is there something Im not thinking of? No, I cant read a wiring diagram because I never learned how but I understand how it works and once I see it done and read how it works, I can do it fine. I have wired and rewired a few motors, just not this size. I am about to go back to my 1/2 hp, at least that just bogged a little, it never tripped a breaker.
 
Ya something's not right there. Even hooked up to 120V and with a max current draw of 13.6 amps it should be fine. It doesn't even draw that amount unless if you've got it fully loaded. That 13.9 is the FLA which stands for Full Load Amps. You're actually only supposed to load a circuit to 80% or 12 amps but that's only a safety thing will work all day at 15A. Personally I would also use the 20A 12/2 circuit as it's safer but without me actually being there I have no idea of the problem. I think it's either an internal wiring problem or the motor is toast and something wrong with the windings inside
 
I just woke up and I'm reading this thread here not having had my coffee yet, so pardon me if this is a dumb observation. But you do realize that if you put two hot legs to it, but they're both the same hot leg (in phase, not 180 deg out) than you're basically providing zero volts and the motor will do as you've described.

You need two opposite hot legs to get 240...

I'll go get some coffee and see if this makes any sense...
 
I think he knows this but he's using a 220V breaker. Unless its quite an old panel the phase's will be staggered. Some panels are not though and you have to make sure when choosing a location to put the breaker. I agree he needs to get a cheap multimeter to test the circuit first. It'll be used again for other things and everyone who has a shop they work in should have one. but it's tripping at 115V as well and it shouldn't
 
Sounds like the problem is the motor or motor wiring. Most likely the wiring. Where the feed connects to the motor there should be multiple wires that are numbered. These have to be rearranged to switch the voltage not just the panel end. The problem of the motor getting hot and thermally overloading but not tripping the breaker is indicative of this. Why do you want to run at 240V instead of 120V? Power is the same either way... Power= amps X volts. 13.6 amp 120v load should be on a 20amp circuit with 12 wire. Although the 14 wire is adequate for the FLA this does not account for the inrush current at start up. Through the years this will burn the 14 wire.
 
running at 240 will have the motor at 6a vice 13a meaning less load on my panel and I can run a light or small vacuum. I figured out the issue with the motor trip.. it took me to write that it was a capacitor motor before I remembered that I cant start with a full load. So back to the 20 a, raised the motor (its on hinges) counted to 10, lower and voila, running fine, no trip. I had a look at the main breaker and I think I do need to switch the legs, I will try it later and see. Yes, I know I should get a meter, I had one but lost it in the divorce.. it was in the house, not the shed. Thanks for the advice guys. I should really take a course.
 
You actually won't be pulling less load on panel with 240 volts. 120 volts would pull 13 amps on one leg while the 240 volts would be pulling 6.5 amps on 2 legs. Either way you are still using the same amount of electricity.
 
Nathan is getting at what I was saying. If both legs of the 220 double breaker are wired to the same input leg, all you'll get is no differential = no power.

Get a meter and read the quad box breakers and see what is the voltage from one 220 mini to the mate. I'm betting they are both on the same leg. In that case, all you need to do is switch the wire from one of that pair to one of the other breakers, and you should have two legs. If things are right, you will read 220 across the tow power wires.

If that isn't the problem, carefully check the jumpers on the motor, and see that all are switched to the 220 configuration.
 
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Odog27 has the answer when running on 115 volt, the 15 amp breaker won't handle the inrush current upon startup. It needs a 20 amp circuit.
 
Junkyard mechanic method, wire two leads of 2 pigtails together put 60W bulbs in the sockets
now wire one to each 110 hot lead, if both bulbs light you're getting 220.
Ken.
 
Ken, you're going to get this guy killed man. ;p

I understand what you're saying, but I speak the language. That plan wouldn't have made any sense to me if not. Just sayin', no offense intended. :)
 
Nah. If you want to see if it's hot, just stick your tongue to it.

(do not actually do this)
 
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