Oneida Air Mini Gorilla tripping breaker- help

[Randy Hermann]

Oneida has been great and sent out a new motor unit. Either two bad units or the problem is somewhere on my end, and that's where I am looking more now.

12G wire, approximately 30'. No visible/obvious damage to wire sheath.
Leviton duplex 20A outlet. Wiring triple checked and is okay visually, tug-test, and per meter
3' "downstream" is a ceiling mount LED bulb on a pullstring. Keeping the light turned off does not fix the problem. Fixture wiring triple checked and is okay visually, tug-test, and per meter.
Breaker is Square-D HOM HACR 20A, single pole, new, and tested in multiple breaker box locations. White wire is to ground bar, black to breaker. Solid connections.

The breaker seems to trip about every third COLD start. Never twice in a row. Never once the unit has been running and is re-started.

I'm down to three options, I think. Please let me know if there are others.
1) Faulty wire. Easy enough to replace but seems REALLY unlikely, doesn't it?
2) Faulty outlet
3) Faulty light socket.

I guess I'll replace the outlet first, cheapest and easiest.

Love to hear some other ideas as I am at a loss.

Separately, now I feel incredibly guilty that Oneida has this expense even though they were stumped too. How do I make it up to them?

Thanks,
Randy

[Peter Christensen]

At this point I would get another wire and run it strait from the box to the motor. That way you can rule out the existing wiring. If it solves the problem you tear into the existing wires and boxes. If the problem continues then it is the breaker.

[Brice Rogers]

You certainly have a perplexing issue that seems to be hard to nail down.

Have you tried measuring the current at the box? There is an instrument called a clamp-on ammeter (HF sells a variety from $14 to $60). You just clamp the current probe around the wire from breaker. It will let you measure the current during start up and also during run.

A previous recommendation was to measure the voltage at the motor during start up. That is another good idea. I have had a breaker one time that didn't make a good connection to the breaker box buss bar. There was some crud on the buss bar. A bit unusual, but possible. If you measure a significant voltage drop at the motor on start up, then you would also want to measure it again at the breaker box. Sometimes power is routed through receptacle boxes in a "daisy-chain" manner. That is, there are receptacles in series. Sometimes the wires are wrapped around the receptacle screw terminals and sometimes the receptacles were wired by "stabbing" the conductor into a hole in the receptacle. This measurement at "both ends" could also uncover a bad splice somewhere.

[David L Morse]

I have an idea about what might be going on here but I need one more piece of data: How quickly does the breaker trip?

a) Several seconds, the motor starts to get up to speed but then quits.

b) A fraction of a second to maybe one or two seconds, the motor hums a bit but doesn't spin at all.

c) Instantly, the breaker might as well be mechanically connected to the switch.

[Randy Hermann]

David, it typically trips in the first 1-2 seconds. I vaguely remember it tripping almost instantly a couple of times. It never trips after getting up to speed.

I have new wire, new outlet, and am on my way to rewire it... Going to start with the new outlet and see what happens.

Meanwhile my sump pump decided to run continuously. Ugh. Must be a frozen drain pipe.

[David L Morse]

David, it typically trips in the first 1-2 seconds.....

Oh, so the motor is already spinning before the breaker trips. Definitely not the problem I was considering.

[Randy Hermann]

Well crud. New outlet on "old" wire seemed to be working until it wasn't.

"Old" (it was new at the start of this project) outlet on new 12/2 wire also failed.

I swapped the breaker with one from our remodel about 8? years ago, actually moved it to that spot which is about 8 slots down in the panel. At this point, if it fails, it seems to be a panel problem of some sort and that seems REALLY weird, doesn't it?

[Brice Rogers]

Randy I replied to the thread but you may not have seen it.

Have you tried measuring the current being drawn? There is an instrument called a clamp-on ammeter (HF sells a variety from $14 to $60). You just clamp the current probe around the single wire from breaker. It will let you measure the current during start up and also during run.


A previous recommendation was to measure the voltage at the motor during start up. That is another good idea but I'd suggest going an additional step. I have had a breaker one time that didn't make a good connection to the breaker box buss bar. There was some crud on the buss bar. A bit unusual, but possible. If you measure a significant voltage drop at the motor on start up, then you would also want to measure it again at the breaker box. Sometimes power is routed through receptacle boxes in a "daisy-chain" manner. That is, there are receptacles in series - from one to another to another. Sometimes the wires are wrapped around the receptacle screw terminals and sometimes the receptacles were wired by "stabbing" the conductor into a hole in the receptacle. So, one bad connection in the series can be the source. This measurement at "both ends" could also uncover a bad splice somewhere. So measuring at both ends may shed some light on the source of the problem.

[Frank Pratt]

I'm speaking from a Canadian point of view & am not sure if the NEC has the same provisions. A 16A is the most continuous load that will reliably run on a 20A breaker. It is not uncommon at all for a motor, that is running on a minimally sized circuit, to trip the breaker on startup. The CEC allows a circuit that is dedicated for a motor load that has problems starting to have a circuit breaker that is up to 250% of the FLA rating of the motor. The wire only has to 125% of the FLA.

So for this motor, you could stick with #12 (16A X 1.25 = 20A) and put up to a 40A breaker on it. But this circuit can have nothing but the collector & it must be hard wired. I just about guarantee that will solve this problem.

CEC & NEC are mostly harmonized now, but again, this is as per CEC, so make sure that you can do this in your local.

[Randy Hermann]

Thanks for the suggestions and ideas. I am putting in long days working at the Sam Beauford Woodworking Institute this week and haven't had time to mess with it any more. I will send an email to Oneida asking what they want me to do. Hopefully I can send them my original unit back (no swapping motors again) and they can test it in-house. If they don't find a problem with it then I know it is on my end, if they do then I know... I can handle manually resetting the breaker for another week, esp. since I won't really be doing anything with it.

[Guy Donham]

Randy,

The 20 AMP 120 V circuit should have 12 gauge wire. You are correct about that. The outlet is not your problem. You need to check the current the unit is pulling. You can hook up a multi meter in series with the unit and see what the amperage really is. If you have had two motors trip the breaker then it is obviously pulling more current than 20 amps. Breakers do go bad but you have replaced the breaker with a working one and you have the same problem. If you can borrow one of the clampon amp meters that would be just about as good as setting up in series. Setting up in series is more problematic for someone that does not really have a good grasp of electrical theory. Plus you need to make sure your amp meter has at least a 30 amp fuse or you will blow the fuse if it is pulling over 20 amps. The circuit is simple as you stated, black is hot and white is neutral. I did not see you mention ground. The bare or green wire should be hooked up to the ground lug. Do not use neutral for ground. Neutral and ground are not the same. Many people think they can just put the neutral over to the ground and the circuit is protected. This is not so and there can be a potential between neutral and ground that causes fires.

So if you unit is pulling 16-18 amps (16 amps is 80%) the 20 amp circuit is ok, if the unit is pulling over 18 amps you need to upgrade to a 30 amp circuit with 10 gauge wire. I cannot image that a small dust collector would pull more than the 18 amps needed for a 20 amp circuit.

You also mentioned that you had other equipment on this circuit, the total of all things attached to the 20 amp breaker is what is being measured by the circuit breaker, maybe the other things on this branch are pulling more than you think. Remove everything from the circuit but the dust extractor and see if the problem is fixed. Also check the wiring at the other outlets in this branch for loose or corroded connections. Remember to turn off the breaker before checking the wiring.

[Kevin Beitz]

In your words "White wire is to ground bar,"
Check to see if your white wire is on the neutral bar... Not the ground bar.
My next step would be to see if you have a shorted switch...

[Randy Hermann]

Yes, to the neutral bar. Sorry for the mistake.

I tried moving the breaker up the box on the same side and it tripped the first time- not necessarily significant, but very convenient. I then moved it to the other half of the box.... and have 10 starts so far. Another full day tomorrow so I won't be able to test more until tomorrow night but so far... fingers crossed!

Dang it. Tripped on the 11th try

[Frank Pratt]

What about the voltage? Have you measured it? If the utility is a little low & you have a long incoming service feeder, you could have a lower than optimal voltage at the motor during starting. As I said earlier, a 20A breaker on a motor that size is kinda borderline already with regards to handling the starting current. An under voltage condition can drive that current up considerably. If had the same result with 2 different motors then it's highly unlikely the problem is with the collector.

[Darcy Warner]

A person needs several meters to check this stuff. Could have been solved right away with a couple meters, vs. just throwing parts at it.