wrote in message

On Fri, 11 Sep 2009 13:23:39 -0400, "Twayne"
wrote:

"Wayne Whitney" wrote in message

On 2009-09-11, Tony Hwang wrote:

You keep talking about winding insulation. We are talking about
surge(spike)

A balanced surge on the hot returning on the neutral will have no
effect on the GFCI. Only if it leaks to ground will it trip a GFCI.

Cheers, Wayne


I only mention this because too many people thing GFIs work on the
ground lead:

It's strictly an imbalance between Hot and Neutral: whether the
current goes to gound or anywhere else. GFCIs do not require the
ground lead to operate and don't care about it. It's an assumption
that a voltge difference will be to ground but it could be to any
other place such as another line or short between adjoining cables
by a nail, etc. etc..


Or extreme cases of power factor - leading or lagging current??????

Yup; that's the inductive/capacitive arguement for their tripping. But
if you think about it, even surges/spikes from a motor may be
latitudinal and not longitudinal. I know it's true that they don't
false-trip nearly as much these days so I think I might have to see if
there are any articles that explain how they do that. Maybe it's the
dv/dt they've started to look at.

Twayne`