You have a problem Dave.
Maybe a bad ground on the fan, water in the loc it is.

On 9/4/2011 9:09 AM, Dave wrote:
On Sun, 04 Sep 2011 13:57:52 +0100,
wrote:
Why should a 1hp motor trip a GCFI, its an earth fault current trip not a
current overload device.

That's something I can't answer because my electrical knowledge is
pretty limited. However, the small 8" desk fan I use in my bathroom
which is plugged into a GFI outlet, occasionally trips the GFI when I
turn the fan on. What could be the explanation for that?