bathroom GFCI tripping!


Old 06-11-07, 07:16 PM
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bathroom GFCI tripping!

I wired a new line from the main panel w/ 20 amp breaker to my new bathroom in the basement, 12 gauge to a 20 amp GFCI a few feet from the pedestal sink. I then used the GFCI output to connect a combination light/fan, 120 watts of light and 80cfm fan that probably draws 2 amps tops. I don't have another free line to run to the bathroom, panel is full.

When I switch the fan off and on fast, it trips the GFCI. Occasionally, turning on the fan a single time will trip the GFCI. The light never trips the GFCI.

I know the 20amp GFCI should have its own line, and I will rewire it using some pigtails to bypass it to power the fan/light, but why should the fan be tripping the GFCI? Could I have a defective fan motor, or GFCI, or something is shorting?

The electric guy from home depot said the fan motor is fooling the GFCI that someone is being shocked. How do it know?
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Old 06-11-07, 07:25 PM
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No, the bathroom receptacle does not need it's own line. It can if you want, but your setup is fine. I would, however, wire it so that the fan and light are NOT GFCI protected.

Did you use a brand new modern GFCI? Older GFCI receptacles are more prone to leakage current from motors, and your fan (surprise) has a motor. If you did not use a new GFCI, then replace the one you put in.
Old 06-11-07, 07:45 PM
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It is a brand new 20 amp receptacle from Home depot I bought as a 3 pack, although it is the cheapest of the three brands they sell. It would be easiest for me to put in another 20 amp receptacle than to rewire the box with added pigtails to get the fan/light out from behind the GFCI, would you suggest I try this first?

Old 06-11-07, 08:45 PM
Join Date: Aug 2005
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You probably won't need to make any pigtails. There is usually space for two wires under each screw on the GFCI. Put the both the LINE and LOAD wires under the LINE screws and you're done. The receptacle will be GFCI-protected, but nothing else.

If you put a new one in, another new one probably will be no different.
Old 06-12-07, 05:18 AM
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Remember that if your exhaust fan is installed over the footprint of the tub or shower most installation instructions call for GFI protection.
Old 06-12-07, 06:46 AM
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Is the fan also brand new? As motors age, they sometimes develop more current leaks to ground that can trip a GFCI.

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