Timer Switch tripping GFCI

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Old 08-03-18, 08:38 AM
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Timer Switch tripping GFCI

I purchased a Honeywell timer switch for a light outside my garage access door. I hooked it up initially and thought I was doing something wrong because it was not working, but after troubleshooting with a handyman, I have basically determined that the GFCI in my garage is tripping whenever I hook up the switch. Even returned the original switch and got a replacement, which is also tripping the GFCI in the same way. I put the regular switch back in and it works fine. Do I need to purchase a different switch because the one I purchased has too much juice for that particular circuit? Am I just out of luck and won't be able to install a timer switch for that particular light? Any thoughts are appreciated.
 
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Old 08-03-18, 10:19 AM
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Hi, the GFCI will not trip on overload, how many wires are on the time switch? does it require a neutral?
Geo
 
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Old 08-03-18, 01:38 PM
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Geo has hit upon a problem.... the neutral. If the timer doesn't require a neutral wire..... it cannot be used there. The timers that don't use a neutral wire get their "neutral" connection from the ground. This will cause then GFI to trip as it's considered a leak to ground.

I can recommend a timer that doesn't require a neutral if you are interested.
 
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Old 08-03-18, 04:07 PM
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The timer does require a neutral, so attaching white wire to neutral, black wire to line and blue wire to load.
 
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Old 08-03-18, 04:21 PM
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Oh my, the only other thing would be to try a different brand of timer.
Geo
 
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Old 08-03-18, 04:25 PM
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Is the timer in the same box as the GFI receptacle ?
You may have used the wrong neutral.
 
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Old 08-03-18, 04:29 PM
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No, the GFI receptacle is on a different wall in the garage. Only 3 wires in the outlet where I am trying to install the timer. One bare (the neutral) and two black. Used voltage tester to determine which of the black was the line and which was the load.
 
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Old 08-03-18, 04:47 PM
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one bare ??
A bare wire is not a neutral..... it is a ground. You cannot connect the timer neutral to ground.
 
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Old 08-03-18, 04:58 PM
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OK, so what do I connect the white wire to? I have the same timer at another location and connected the white wire to the ground (from what you are saying) and it is working fine.
 
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Old 08-03-18, 05:03 PM
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That will incorrectly work on a non-GFI circuit as the imbalance is not seen.
On a GFI protected circuit.... a connection between hot and ground is seen as a leak and will trip the GFI.
 
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Old 08-03-18, 05:12 PM
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OK, makes sense. So can I use the timer on the GFI circuit or not because I have nowhere to connect the neutral? If that is the case, you mentioned up above that you can recommend a timer that doesn't require a neutral and it sounds like that is the route I probably need to go. Any recommendations are appreciated.
 
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Old 08-03-18, 06:25 PM
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Is this circuit in conduit, how can there be 2 Blacks and a bare ground?
You have another issue there,
Geo
 
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Old 02-22-20, 07:21 PM
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I had the same problem adding a timer switch to my pool light. I found the solution to be running the neutral from the timer switch back to the load side neutral on the GFCI. I believe this keeps the GFCI balanced and therefore it doesn't trip.
 
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Old 02-22-20, 09:16 PM
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Welcome to the forums.

Yes..... getting the timer neutral from the load side of the GFI is the proper connection method.
That's one benefit of having a conduit.

Hopefully this member has worked out his problem as this is an older thread.
 
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Old 02-22-20, 09:21 PM
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The timer neutral needs to go to same side of the GFCI as the hot. It only goes to the load side if the hot goes to the load side. Not everyone hooks the lights to the load side. They don't want the light to go off if the GFCI trips.
 
 

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