Help me Make my GCFI Stop Tripping

middle.road said:
minuscule drop or increase in voltage causes a GFCI to trip doesn't it?
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Only if the voltage is leaking to ground. It is possible though that rough bearings increased the current draw of the motor beyond what the circuit breaker is rated for.
 
MontanaLon said:
Only if the voltage is leaking to ground. It is possible though that rough bearings increased the current draw of the motor beyond what the circuit breaker is rated for.
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I thought it was if there was fluctuation between the Hot and Neutral? I'm thinking two prong plug equipment...
But then I'm not very good at electricity at times.
 
middle.road said:
I thought it was if there was fluctuation between the Hot and Neutral? I'm thinking two prong plug equipment...
But then I'm not very good at electricity at times.
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I think your correct they check for differential between the two lines as if there was a dangerous fault condition it might be leaking through a human being to ground not down the earth wire.
 
I'm not an electonicker, but here's my understanding of how a GFCI works. Think of wiring two transformers in series with the load - one on the "hot" side and one on the "neutral" side. Then connect the secondaries of the transformers in series, with one of them reversed. As long as the amount of current coming in on the "hot" side is exactly the same as the amount of current leaving on the "neutral" side, the two secondary voltages will be exactly the same. So they'll cancel each other out and the series voltage will be zero. Now introduce a little bit of leakage to ground somewhere in the load. When this happens, the outgoing current will be different from the incoming ... part of it is taking a different path. So the voltages of the two secondaries will differ and they won't cancel exactly. A circuit in the GFCI detects this small voltage, and if present, it will trip the switch.

I read somewhere that a GFCI will trip if the imbalance between gazinta current and gazata current is as low as 5 milliamps. That's below the threshold of harmful current for a human being. So a GFCI is designed to save your life.

Two failure modes are possible - either the GFCI will fail to trip at 5 milliamps or higher, or else it might trip at a much lower threshold. I'm pretty confident that the GFCI circuitry is well designed to be fail-safe, so the former scenario won't happen. But the latter scenario remains possible and would result in nuisance tripping.
 
hman said:
I'm not an electonicker, but here's my understanding of how a GFCI works. Think of wiring two transformers in series with the load - one on the "hot" side and one on the "neutral" side. Then connect the secondaries of the transformers in series, with one of them reversed. As long as the amount of current coming in on the "hot" side is exactly the same as the amount of current leaving on the "neutral" side, the two secondary voltages will be exactly the same. So they'll cancel each other out and the series voltage will be zero. Now introduce a little bit of leakage to ground somewhere in the load. When this happens, the outgoing current will be different from the incoming ... part of it is taking a different path. So the voltages of the two secondaries will differ and they won't cancel exactly. A circuit in the GFCI detects this small voltage, and if present, it will trip the switch.

I read somewhere that a GFCI will trip if the imbalance between gazinta current and gazata current is as low as 5 milliamps. That's below the threshold of harmful current for a human being. So a GFCI is designed to save your life.

Two failure modes are possible - either the GFCI will fail to trip at 5 milliamps or higher, or else it might trip at a much lower threshold. I'm pretty confident that the GFCI circuitry is well designed to be fail-safe, so the former scenario won't happen. But the latter scenario remains possible and would result in nuisance tripping.
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The GFI (RCD) should be rated , mostly in europe they are 30mA or 50mA

30mA is considered good for life protection ,

 
A high load on the motor will NOT trip a GFCI. It does not even look at the load. With the motor disconected from the house wiring, take your ohm meter and check the motor leads, check from black to green, and from white to green. They must both read infinity. If they do not, you have an electrical issue with the motor. The bearing will have no effect on the GFCI.
 
Flyinfool said:
A high load on the motor will NOT trip a GFCI. It does not even look at the load. With the motor disconected from the house wiring, take your ohm meter and check the motor leads, check from black to green, and from white to green. They must both read infinity. If they do not, you have an electrical issue with the motor. The bearing will have no effect on the GFCI.
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They do make combined breakers and GFI devices. since the OP hasn't said what make and model he has it's difficult to know.
 
The circuit breaker will respond to load of course, but the GFIC will not. Some of those just trip and you can not tell why it tripped, others have a seperate trip for GF vs over current. Yes it will help if we know what type of protection the OP has.
 
Flyinfool, thank you for voicing sanity and clarity on what a Ground Fault circuit does. I would have hoped from the name itself its function would have been clear, but apparently I was wrong.
Personally I would be going through the electrics very thoroughly at this point before doing anything else on this machine.
 
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