Rug Doctors and "smart" QO breakers

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ModbusMan

Senior Member
Location
Cleveland, OH
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Building Automation Engineer
Curious if anyone has seen this, or if perhaps my local Home Depot has seriously dangerously botched things up...

Twice now, I've rented a Rug Doctor Mighty Pro X3, and attempting to power it from either the general basement receptacles (dual-function CAFCI/GFCI) or the dedicated washing machine circuit (GFCI only) results in immediate breaker trip. Power it from the panel convenience outlet (which has zero "smarts") and thing thing runs fine for as long as I need it. All circuits in question are 20A. The only thing I can think of offhand that might explain this is that the plug on both machines (and I was given a different one each time) appears to have been replaced at some point, unless Bissell is in the habit of not using molded plastic plugs, and whoever at Home Depot did the work accidentally reversed the neutral and ground leads. I plan on reporting this when I return the machine tomorrow morning rather than disassembling the plug myself (and opening up who knows what kind of future liability issues), but figured I'd ask if anyone here's seen the same/similar, or if I might be missing something else that should have been obvious.
 
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ModbusMan said:
... the plug on both machines (and I was given a different one each time) appears to have been replaced at some point
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Those machines come with an ALCI plug like a hair dryer. It provides GFCI type leakage detection. Apparently, they were cut off and replaced with regular plugs so your theory may be valid.

-Hal
 
hbiss said:
Those machines come with an ALCI plug like a hair dryer. It provides GFCI type leakage detection. Apparently, they were cut off and replaced with regular plugs so your theory may be valid.

-Hal
Click to expand...
They were probably having a problem with the factory plug tripping, so they cut it off, instead of making the factory fix the issue. Probably an internal leakage, such as a Chinese water or chemical pump.
 
Does the machine have solid state motor controller(s)? If so those are known to commonly not play well with AFCI/GFCI technologies.

If you use one again and have this trouble, just out of curiosity I would plug it in via one of those three to two prong cheater adapters. 99% chance it holds that way. High frequency leakage, but with no EGC it has no where to flow to is why it won't trip.
 
No idea if it's got one of those motor controllers, but I rather doubt it. Just an on-off-on switch (for hose-off-floor), and a push button to spray the water+detergent mix. I also don't know if I've got any cheaters laying around... nobody I know has had need of them since SIL sold her post-war bungalow.
 
ModbusMan said:
Curious if anyone has seen this, or if perhaps my local Home Depot has seriously dangerously botched things up...

Twice now, I've rented a Rug Doctor Mighty Pro X3, and attempting to power it from either the general basement receptacles (dual-function CAFCI/GFCI) or the dedicated washing machine circuit (GFCI only) results in immediate breaker trip. Power it from the panel convenience outlet (which has zero "smarts") and thing thing runs fine for as long as I need it. All circuits in question are 20A. The only thing I can think of offhand that might explain this is that the plug on both machines (and I was given a different one each time) appears to have been replaced at some point, unless Bissell is in the habit of not using molded plastic plugs, and whoever at Home Depot did the work accidentally reversed the neutral and ground leads. I plan on reporting this when I return the machine tomorrow morning rather than disassembling the plug myself (and opening up who knows what kind of future liability issues), but figured I'd ask if anyone here's seen the same/similar, or if I might be missing something else that should have been obvious.
Click to expand...
How long is the cable on the machines? I've seen trips on motorized tools when used with extension cords that have no issues when used without the extension. And my cords are #10 or #12, so under sizing is not the issue. I figure that the cord causes too much delay from the time the hot draws current until the neutral is balanced at the "smart" device. Just my take on what I've seen.
 
Maybe around 15ft? Long enough that I could get anywhere in the basement without an extension cord using the finished portion's receptacles, or just the cat-inhabited portion using the washing machine. Probably worth mentioning that my regular vacuum cleaner works just fine on the basement circuit, so run length probably isn't to blame.
 
This is why I have my own megger. Every time I replace a male plug or switch on any tools I megger it with 250 volts then 500 volts. When I worked at a large slaughter house back in the 1970' s workers in the large damp chill box preferred using 120 volt Well saws to break down side of hanging beef gather then air driven saws. Even a two week brand new well saw would give workers shocks. We would measure them just using a Simpson model 260 VOM on ohms and picked up a few thousand ohms to ground when the two pole switch was pulled. Would leave them in the boiler room for 12 hours and readings were great and would be a few weeks until shocks returned. I suggested they make an insulated stainless steel box with a thermostat & heater to store them close by but they didn't like that ideal. These saws had universal motors that had brushes and my thinking was the brush holder built up moisture causing some leaks to ground. Most young sparkies did not know what a universal motor was. Easy it has a winding that goes thru a brush holder thru the armature then to a second winding. Only motor at least back in those days that could run on AC or DC and could produce speeds of 10,000 RPM while powered on 60 Hertz.
 
OldSparks said:
How long is the cable on the machines? I've seen trips on motorized tools when used with extension cords that have no issues when used without the extension. And my cords are #10 or #12, so under sizing is not the issue. I figure that the cord causes too much delay from the time the hot draws current until the neutral is balanced at the "smart" device. Just my take on what I've seen.
Click to expand...
I had that issue with a hydraulic bearing press. It would trip the breaker every time when plugged directly into the outlet next to the panel, but put it on a 100’ 12 gauge extension cord, it worked fine. Did some research, and found that a standard QO breaker does not play well with heavy motor loads. Changed it to a QO high magnetic breaker, solved the problem.
 
ModbusMan said:
No idea if it's got one of those motor controllers, but I rather doubt it. Just an on-off-on switch (for hose-off-floor), and a push button to spray the water+detergent mix. I also don't know if I've got any cheaters laying around... nobody I know has had need of them since SIL sold her post-war bungalow.
Click to expand...
Since the cord end seems to be obvious that it is not original, maybe they got neutral current returning on the grounding pin?
 
OldSparks said:
How long is the cable on the machines? I've seen trips on motorized tools when used with extension cords that have no issues when used without the extension. And my cords are #10 or #12, so under sizing is not the issue. I figure that the cord causes too much delay from the time the hot draws current until the neutral is balanced at the "smart" device. Just my take on what I've seen.
Click to expand...
current is same at every point in the circuit.

What you likely had happening and is pretty common particularly with standard QO 15 and 20 amp single pole breakers is they have a lower magnetic trip setting than competitor versions of these breakers. Not sure whether their AFCI and GFCI versions have lower mag trip or not, seems likely they do not but I don't know for certain. When you plug it in via extension cord and it now will start without tripping, you have added enough circuit resistance to limit the starting current enough to not get into magnetic trip range. Square D does have single pole 15 and 20 amp standard breakers with a HM (high magnetic) suffix in the catalog number that have a higher magnetic trip setting and use of those also will solve this problem.
 
It sounds like it's the QO that's the problem. Does this issue exist with other manufacturers circuit breakers? I have an air compressor that would constantly trip the 20 amp QO circuit breaker (my own garage so I installed a 30 amp don't tell anyone). When I moved to my current home I installed a garage sub-panel and and now it's run on an Eaton 20 amp circuit that has never tripped.
 
kwired said:
Since the cord end seems to be obvious that it is not original, maybe they got neutral current returning on the grounding pin?
Click to expand...
Could be that whoever put the new plug on had no idea what wire went on what screw... or worse yet the cord might have the international color code - brown, blue, green with yellow stripe.

Or they might have been color blind. :rolleyes:

-Hal
 
infinity said:
It sounds like it's the QO that's the problem. Does this issue exist with other manufacturers circuit breakers? I have an air compressor that would constantly trip the 20 amp QO circuit breaker (my own garage so I installed a 30 amp don't tell anyone). When I moved to my current home I installed a garage sub-panel and and now it's run on an Eaton 20 amp circuit that has never trippe
Click to expand...

I believe OP said it was on an AFCI. Not sure if Square D has low magnetic trip on those or not. I know they do on the standard 115 and 120 breakers, and have since possibly day one of introduction of the QO line? If not has been for at least 40 or even 50 years.
 
infinity said:
...sounds like it's the QO that's the problem. Does this issue exist with other manufacturers circuit breakers?
Click to expand...
The QO family was designed with a 'qwik open' feature on its 15 & 20A 1P breakers. Effectively these have a magnetic trip point of 6-8X versus every other manufacturer that has 8-10X point. The HOM family uses the same internals but i do not know if it has qwick open.
 
hillbilly1 said:
I had that issue with a hydraulic bearing press. It would trip the breaker every time when plugged directly into the outlet next to the panel, but put it on a 100’ 12 gauge extension cord, it worked fine. Did some research, and found that a standard QO breaker does not play well with heavy motor loads. Changed it to a QO high magnetic breaker, solved the problem.
Click to expand...
Hard to believe a little carpet cleaner is pulling a higher inrush than my AC ;)

kwired said:
Since the cord end seems to be obvious that it is not original, maybe they got neutral current returning on the grounding pin?
Click to expand...
hbiss said:
Could be that whoever put the new plug on had no idea what wire went on what screw... or worse yet the cord might have the international color code - brown, blue, green with yellow stripe.
Click to expand...
This (N/G reversal) is what I think happened, and not wanting to take it apart myself, the answer that best fits Occam's Razor.

kwired said:
I believe OP said it was on an AFCI. Not sure if Square D has low magnetic trip on those or not. I know they do on the standard 115 and 120 breakers, and have since possibly day one of introduction of the QO line? If not has been for at least 40 or even 50 years.
Click to expand...
Both a combo AF/GF breaker (basement receptacles) and a GF-only (washing machine) have the immediate trip issue. The "dumb" QO120 works just fine.
 
Barbqranch said:
Should be able to check for that w/ an ohm meter.
Click to expand...
He didn't want to take the plug apart, if you want to check with an ohm meter, you would have to take something apart to check for continuity between the neutral, or hot, prong to the other end of the cord where it attaches to the connections for the machine.

So either way, something is going to have to be taken apart to do this. Unless I'm missing something.
 
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