Exterior light and GFCI recptacle mystery

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Old 05-02-14, 02:59 PM
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Exterior light and GFCI recptacle mystery

I have an outdoor GFCI receptacle that has never worked properly. When I moved into this house 5 years ago the test and reset buttons did nothing even though the line wire was hot. I replaced the receptacle with a new weather rated GFCI receptacle. It worked at first, but a week later there was no power and the test and reset buttons had no effect. I took the receptacle out and rewired it. It worked for a couple of days then it had no power and the test and reset buttons did nothing.

It's been like that for 5 years and I've never had any problems with the light that is 4 feet directly above the receptacle. Now I'm replacing my deck and I thought it would be nice if the receptacle worked. I disconnected the line and load from the receptacle and turned the circuit back on. The line was hot and the load was not - so far so good. I reconnected the line and left the load unattached. I wanted to confirm that the outdoor light and switch were on the GFCI's load so I removed the switch plate and used a non-contact voltage detector. To my surprise the switch has power and when I operated the switch its load wire became hot... but the light fixture did not turn on!

Maybe this part is not relevant, but... I turned the circuit off and started to remove the exterior light fixture (mounted to my aluminum siding) but the I saw a spark and my bathroom GFCI circuit tripped. I finished removing the fixture and I can see an additional wire in there just cut with no wire nuts. My voltage detector doesn't show it being hot, but it might be.

So the fixture wire only becomes hot when the load wire is connected to the GFCI outlet. How is that possible? Where is the light switch wire going?
 
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Old 05-02-14, 03:27 PM
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used a non-contact voltage detector.
Measurements made with a non contact tester are to unreliable to be meaningful and should be disregarded. You need to test using an analog multimeter with all wires disconnected.
my bathroom GFCI circuit tripped.
So best guess the receptacle is fed by the bath GFCI (a common practice in older homes) and the receptacle feeds the light switch. This may also be a clue to your problem. If the outside receptacle is fed from the load side of the bath receptacle it should not have a GFCI receptacle.
 
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Old 05-02-14, 04:29 PM
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The receptacle and switch are on a different circuit (living room circuit - far away from this wall), but I think they may have originally been on the bath GFCI. When I renovated the upstairs bathroom I followed a wire that went down that wall but couldn't find anything that didn't have power when the circuit was switched off. Just the 2 baths, the 1/2 bath and the garage receptacle plus a wire leading nowhere.
 
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Old 05-02-14, 04:46 PM
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I can't believe it - the switch powers both the receptacle and the light fixture. I been running extension cords for 5 years thinking there was bad wiring in there. I'm going to run a new wire from the switch to the fixture.
 
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