GFCI trips every time I turn on bathroom light....??

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  #1  
Old 03-03-12, 06:05 PM
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GFCI trips every time I turn on bathroom light....??

Hi,

I have a GFCI in the bathroom that would not 'test'. Upon opening, I found that the previous homeowner had all 4 wires (2 blacks and 2 whites) going into the load side. There is a black and white coming in from the side of the box (which I am guessing is one cable), and another black and white coming in from the top of the box. I determined the line wires from load wires by capping one pair of black and white (the ones coming in from the side) and connecting the other pair to a std receptical with a nighlight plugged in. I then seperated the line from load wires on the GFCI and reinstalled. Now, the 'test' and 'reset' buttons work with the nightlight plugged in, but every time I turn on the vanity light from the switch, the GFCI trips??? I should note, there is also a switch for a bath fan (double gang with light) that does not trip it when turned on.

Any thoughts are much appreciated!! I can't figure this one out!!

Thanks in advance!
 
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  #2  
Old 03-03-12, 06:26 PM
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Have you opened the switch and checked the wiring. Can you post a picture of the switch wiring? http://www.doityourself.com/forum/li...-pictures.html
 
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Old 03-03-12, 07:11 PM
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The solution! (I hope you have a sense of humor as I couldn't resist! )




I suspect that there is some "monkey business" substandard wiring going on between the switches and the fan/light unit. Most likely whoever wired it used the bare equipment grounding conductor as a current-carrying conductor and this is causing the problem. Unless the fan/light unit is located in a shower or over a bathtub (or the manufacturer requires GFCI protection) you could have both the line and load cables connected to the LINE connections of the GFCI receptacle. This would remove GFCI protection from the load cable but still retain the GFCI receptacle in working order.
 
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Old 03-03-12, 08:02 PM
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. I do have a sense of humor with how much substandard work I have found in this house ~ I have to, as it helps me keep my sanity!!!

I will take photos of the switch wiring in the daylight tomorrow and will post. The fan is not over a tub, but I am not sure if the manufacturer requires GFCI protection... Would the fan not work with all cabels in the LINE connections if it does require protection?

Thanks for the initial help!!
 
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Old 03-04-12, 07:01 AM
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From your posts I am assuming you have a somewhat standard bath exhaust fan, not over the shower, that works and a separate light over the vanity that trips the GFI outlet when turned on. I would concentrate my efforts on looking at the wiring between the switch and the light fixture. It sounds like a simple problem and can probably be resolved by removing the light fixture and inspecting the wiring. My opinion though is that it is best to not protect the fan and light with the GFI.
 
  #6  
Old 03-04-12, 07:25 AM
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Here is a photo of the double gang switch; single cable coming in from top. The fan switch is the back one (on the left side), and the light switch is on the right in the bottom of the photo. The ground was just floating in the box - should this be connected? If the issue cannot be seen here, what would I look for at the light wiring? Or, is it suitable to put all of the wires in the LINE connector in the GFCI as you mention, Furd?

http://i1067.photobucket.com/albums/...lund/photo.jpg



Thanks again for the assistance!
 

Last edited by ray2047; 03-04-12 at 09:09 AM. Reason: Embed image.
  #7  
Old 03-04-12, 08:47 AM
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I tried the link to the pics, but it did not work.
 
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Old 03-04-12, 09:15 AM
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Link fixed.

Did you try the switch with the wires pulled out of the box? Sometimes it is just current bleeding to ground. Next you will need to open the vanity light. If no obvious problem mark, disconnect, and cap the wires to the light. Turn the breaker back on and try the switch.
 
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Old 03-04-12, 09:26 AM
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The ground wire should be connected to the box with a 10-32 screw. There is a tapped hole for the screw.
 
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Old 03-04-12, 09:48 AM
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I did not have a 10-32 screw, so I pigtailed the ground out to each of the switches ground screws. For ease of fixing the GFCI (since the wife wanted working lights quickly), I put all connections into the LINE connector, so the lights and fan are not protected, but now it all works! On a rainy day, I will try the troubleshooting you mention, Ray, to see if I can find the real issue with the light wiring.

Thanks for the help all of you offered!
 
  #11  
Old 03-04-12, 11:00 AM
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I put all connections into the LINE connector, so the lights and fan are not protected,
Lights and fans generally do not need to be protected by the GFCI unless recommended by manufacturer or required by code due to location. My personal choice when permissible is lights not GFCI protected so you aren't in the dark if the GFCI trips. You should though try to isolate the issue with the light as soon as possible.

I did not have a 10-32 screw, so I pigtailed the ground out to each of the switches ground screws.
By code the metal box must also be grounded. The green ground screws sold in the electric department of hardware stores and home improvement stores are recommended but any pan head or truss head or hex washer head or round head 10-32 is okay .
 
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