gntry wrote:
I have a dedicated 20 amp line for my pool. I have a GFI outlet by
the deck for the filter. I want to install a single pole switch in
the house to turn the filter on and off from inside. If I install a
switch, will the GFI trip everytime you turn the power off to the GFI?

Not in my experience. I have a couple in the shop, one on the air
compressor, plugged into the GFCI and then to the switch. Turning off the
switch lets the GFI drop out. NBD since it's right next to the compressor,
but it's not really "right". It should be the other way around; GFCI, then
switch, then compressor.
Same for the one on my workbench, though it's seldom without power unless
I trip a breaker to work on something.

I've heard others say no, they don't drop out before, but I haven't yet
found one myself that didn't, nor anyone whose story about same seemed
believable. From what I've seen of GFI designs on the 'net, they operate on
a "latch" system and that "latch" drops when the ac goes away. You always
have to press the button to let power thru a GFI when they're new also,
according to those, so that seems to support my own experience. It might
have been wikipedia; not sure.

HTH
Pop`