General > General Technical Chat

GFCIs and Treadmills

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Sal Ammoniac:
My wife recently got a treadmill and we put it out in the garage, which doubles as an exercise room.

All of the electrical outlets out in the garage are on a circuit with a GFCI. Using the treadmill plugged into any of those outlets will immediately trip the GFCI. When she runs an extension cord into the house and plugs it into a non-GCFI circuit, the treadmill works fine.

Why does the treadmill trip a GFCI and is there any way to prevent this so she doesn't have to run an extension cord into the house to use the treadmill?

soldar:
I would return it.

themadhippy:

--- Quote ---I would return it.
--- End quote ---
yep

--- Quote ---Why does the treadmill trip a GFCI
--- End quote ---
because  the electricity  is leaking out and trying to escape ,just hope it dont use your wife as part of its escape route.

BrianHG:
It's the leakage current into the Earth Ground pin.  Usually, from the class-Y cap being too high between the Hot and Earth Ground.

Remember, some of these GFCI breakers can trip with currents as low at 4ma.

A treadmill has a huge metal chassis and DC motor which will be Earth Grounded, all it can take is too high a class-Y cap with some noisy power, or even some machine oil close to the motor's brushes and it's power lines to excede that 4miliamps tripping your breaker.

Older designs weren't so carefully isolated during UL safety approvals.  A modern treadmill shouldn't get close to this current.

Also with the potential allowed <1ma, if you have other leaky items plugged in all totaling up to ~2-3ma on the same circuit, the treadmill ~1ma to frame ground could be the tripping point.  IE: a few devices, each with a 0.1uf class Y cap on the same circuit will trip the 4ma breaker.  On the other hand, a few devices each with 0.022uf caps wont get close.

My old treadmill's manual states I should use a dedicated circuit for it alone.

BrianHG:
You can use a class C,D and E GFIC breaker:


--- Quote ---Jan 6, 2014 — Class C, D, and E GFCIs trip at 20 mA rather than the 6 mA trip current mandated for Class A GFCIs. This increase in GFCI trip level is ..
--- End quote ---

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