On Tuesday, December 6, 2016 at 4:27:46 PM UTC-6, wrote:
On Tue, 06 Dec 2016 21:44:01 +0000, Tom
m wrote:

I have a new furnace and a condensate pump the code requires the pump to be on
a gfci so they installed a combination switch receptacle the receptacle is
gfci the switch is not the pump is the only thing on the gfci they replaced
the pump and it still trips any thoughts?

Inspect the wiring and be sure there is nothing touching the enclosure
or the ground (hot or neutral)
If you have a meter, be sure you have no continuity between the motor
leads and ground (with it disconnected from the hot and neutral)

I'm wondering if the furnace installer ran the power instead of an electrician or someone with a lot of experience running Romex. I know from experimenting that a GFCI will trip if the neutral touches the ground. The OP didn't write whether or not the GFCI trips when nothing is plugged in or if it trips as soon as the pump is plugged in. It could faulty diagnostics by the Mark-1 installer. ヽ(ヅ)ノ

[8~{} Uncle Tripping Monster