Motor Throw GFI

[ssjones]

I'm setting up my pipe work area in the new garage and an electrical issue has me stumped. I have two motors for buffing, one a furnace motor wired with a switch and plug. Both plug into an protected power strip.
The outlets in my work area, are tied to a GFI outlet on another wall in the garage.
Everytime I plug in my furnace motor buffer, it throws the GFI. Note, this one does not have a capacitor.
I put on:
- new switch on the motor
- new power cord and plug
- new GFI outlet (throught perhaps it was an old, weak GFI
The motor turns on an runs fine other outlets, but throws the GFI plugged into any connected outlets or directly into the GFI

The other buffing motor turns on without drama in any of those outlets.
(this unit ran fine before we moved, no issues)

I'm stumped!

 

[jpmcwjr]

Could the plug be reversed? A WAG, though.

 

[beefeater33]

I'm setting up my pipe work area in the new garage and an electrical issue has me stumped. I have two motors for buffing, one a furnace motor wired with a switch and plug. Both plug into an protected power strip.
The outlets in my work area, are tied to a GFI outlet on another wall in the garage.
Everytime I plug in my furnace motor buffer, it throws the GFI. Note, this one does not have a capacitor.
I put on:
- new switch on the motor
- new power cord and plug
- new GFI outlet (throught perhaps it was an old, weak GFI
The motor turns on an runs fine other outlets, but throws the GFI plugged into any connected outlets or directly into the GFI

The other buffing motor turns on without drama in any of those outlets.
(this unit ran fine before we moved, no issues)

I'm stumped!

I’m just guessing here, but I’m thinking you have a minor ground fault in the furnace motor. GFI’s trip on very low amps- like .005 amps. The motor probably doesn’t have enough of a ground fault to trip a breaker on a regular circuit.

 

[Hillcrest]

Check the amperage as well. The GFI plug might be a lower amperage. You might need to install and commercial for motor usage. An electrician might help.

 

[ssjones]

Could the plug be reversed? A WAG, though.

I reversed, but that blew the non GFI breaker.

 

[ssjones]

Check the amperage as well. The GFI plug might be a lower amperage. You might need to install and commercial for motor usage. An electrician might help.

Ah,I did put on a light duty plug! (But it tripped with the original HD plug

 

[Hillcrest]

Ah,I did put on a light duty plug! (But it tripped with the original HD plug

I have exhausted my electrical knowledge with the above comment. I hire an electrician because I don't trust myself beyond changing light bulbs and fuses. Sorry.

 

[PaulRVA]

Dead short to ground ?

 

[huntertrw]

Does the power-cord to the furnace motor have a three-prong plug (in other words is it grounded)?

 

[RPK]

People are shocked when they find out I'm not a very good electrician

 

[ssjones]

Does the power-cord to the furnace motor have a three-prong plug (in other words is it grounded)?

Yep!

 

[ssjones]

I was tempted to pull the GFI, but we have a laundry tub in that area of the garage, so I better not

 

[woodsroad]

You have a minor ground leak in the motor. There are instruments for measuring this, but my suggestion would be to swap out the GFI breaker for a regular one and forget about it. As long as you have both a neutral and ground going to motor, and you don't plan on putting one hand on the motor housing and the other on the kitchen faucet, you are safe.

Either way, do go back and check the wiring on the switch and make sure the hot isn't near a ground or neutral, but it only takes 6 milliamps of current from the hot to ground to trip a GFI. If it was a pool pump, I'd be worried, but it isn't something to be concerned about if you aren't making yourself part of the circuit. Do check and see if the motor is heating up after you switch it off, as the problem might get worse. A lot of those old motors leaked to ground from day one, though.

Read this for more info, but remember, they are trying to sell you stuff.

And if you you really want to live on the edge, you might get a jolt out of restoring old TV's.

 

[ssjones]

You have a minor ground leak in the motor. There are instruments for measuring this, but my suggestion would be to swap out the GFI breaker for a regular one and forget about it. As long as you have both a neutral and ground going to motor, and you don't plan on putting one hand on the motor housing and the other on the kitchen faucet, you are safe.

Either way, do go back and check the wiring on the switch and make sure the hot isn't near a ground or neutral, but it only takes 6 milliamps of current from the hot to ground to trip a GFI. If it was a pool pump, I'd be worried, but it isn't something to be concerned about if you aren't making yourself part of the circuit. Do check and see if the motor is heating up after you switch it off, as the problem might get worse. A lot of those old motors leaked to ground from day one, though.

Read this for more info, but remember, they are trying to sell you stuff.

And if you you really want to live on the edge, you might get a jolt out of restoring old TV's.

Thanks for this info. I think it really is the old motor. It was in my parents basement, no clue why, I found it 12 years ago and wired it as my primary buffer. When I added a 2nd, dual-arbor buffer, it was relegated to carnuba buff only. I'll pull that GFI.