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Long Ranger Long Ranger is offline
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Default Jet 1442 Problem

"Ben Miller" wrote in message
"Long Ranger" wrote in message
Capacitor start motors are notorious for tripping GFI receptacles.
GFI receptacles are typically designated for use with portable hand held
tools, which a lathe is not.

On what do you base those statements? Where have you seen restrictions on
the type of loads that can be run from a GFCI?

*Single phase motors, (and particularly cheap single phase motors), and cap
start motors are notorious for tripping GFI outlets because they tend to
generate eddy currents in their windings and induce imbalances on the
conductors feeding them. They also reflect current and voltage spikes back
on the feed when they switch off of the start windings. In the early days of
GFI outlets, hair dryers were a big culprit. I don't know if the receptacles
are less sensitive now, or if hair dryers have better motors, but it seems
to have lessened greatly. I don't mean to say that lathes are restricted
from the GFI circuitry. I mean to say that the purpose of GFI protection at
the level of the outlet is targeted towards hand-held tools. That is why you
don't see a GFI on a washing machine. It is a stationary piece of equipment,
and the plug serves as it's disconnect for servicing. Same with a lathe,
unless it is a little tiny bench-top model. Even then, it is a grey area.

It sounds like your motor incorporates a centrifigal switch which is not
opening because it is worn out or fused together, or full of crud.

That could trip a circuit breaker due to over current, but it won't trip a
GFCI circuit, as it is not a "ground fault".

*That was not a reference to the GFI problem. It was a reference to a
seperately described situation. Go back and read the original text. (By the
way, any type of imbalance of sufficient magnitude will trip a GFI, not just
a "ground fault".)
Ben Miller
Benjamin D. Miller, PE