Outdoor porch light trips GFCI

Reply

  #1  
Old 11-01-15, 12:50 AM
Member
Thread Starter
Join Date: Jun 2015
Location: USA
Posts: 6
Received 0 Votes on 0 Posts
Outdoor porch light trips GFCI

Hi All,

I have a light on the porch. The light functions fine and there are no issues when it does not rain. However, when it rains the GFCI goes off. I have disconnected the line feeding to the light from the power line and the GFCI issue goes away. I have disconnect the light fixture (AKA having the end wires hanging in the air) and the GFCI still goes off. The wire runs through the ground and is properly protected through a PCB tube. To summarize:

1. The line connecting the power line to the fixture is what sets off the GFCI even when it is not connected to anything. I have checked the open ended resistant of the line and it 9.6 K ohms, which explains why the GFCI goes off because that translates to 12 mAs which sets off any GFCI.

2. Is the wire the issue? Do I need to replace it then?

3. What is the best approach to replace the wire?

4. Could it be the GFCI because many other things are connected to the outdoor outlets running off of it and it works fine without going off.

Regards,

Chris
 
Sponsored Links
  #2  
Old 11-01-15, 02:34 AM
Member
Join Date: Mar 2006
Location: Wet side of Washington state.
Posts: 18,482
Received 25 Votes on 19 Posts
Is this a GFCI circuit breaker or a GFCI receptacle?

However, when it rains the GFCI goes off.
Do you mean the GFCI trips, removing all power?

I have disconnected the line feeding to the light from the power line and the GFCI issue goes away.
Do you mean that you disconnected the wiring AFTER the GFCI? This would indicate that you have a GFCI receptacle and not a GFCI circuit breaker.

The wire runs through the ground and is properly protected through a PCB tube.
Do you mean a PVC conduit? Is this "tube" approved electrical conduit or perhaps something else like an old garden hose or plastic water piping? Is the "tube" continuous from the source of the power all the way to the light fixture? What kind of "wire" is in this "tube", individual conductors or a cable (more than one wire with an additional overly) assembly?

I have checked the open ended resistant of the line and it 9.6 K ohms, which explains why the GFCI goes off because that translates to 12 mAs which sets off any GFCI.
Please explain, IN DETAIL how you did this test. I am 99.999% certain that whatever testing method you used it is invalid.

Is the wire the issue? Do I need to replace it then?
Probably and most likely.

What is the best approach to replace the wire?
Depends entirely upon what the existing installation is like. Several pictures may help one of us to make some cogent suggestions.

Could it be the GFCI because many other things are connected to the outdoor outlets running off of it and it works fine without going off.
With all the information given so far it is extremely unlikely to be a faulty GFCI device.
 
  #3  
Old 11-01-15, 07:32 AM
Member
Thread Starter
Join Date: Jun 2015
Location: USA
Posts: 6
Received 0 Votes on 0 Posts
Thanks.

1. GFCI receptacle

2. Yes it does remove all power.

3. Yes you are correct on the receptacle.

4. It is a proper conduit for electrical applications that does run from the power source to outdoor light. There is a cable that runs through the conduit. The cable houses the 3 wires. Everything is up to code from what I see because of the way it is setup.

5. I probably agree. I had an open circuit at both ends. Basically I disconnected the wire from the power end and I disconnected it from the light fixture. I had both ends hanging in the air. I used a Fluke multimeter and measured the resistant at the power end between the white and red lines. It read 9.6K ohms. I was expecting to get an OL or open circuit reading.

6. Thanks.

7. I will try to take some photos. But basically it is a conduit opening at one end and at another end there is a light. Is it best to attach a cable to the existing one while pulling it out or should we use a different method?

8. Thanks for the GFCI feedback. That was my feeling.

BTW what would make the line go bad? Could it be that the conduit is also damaged and needs to be replaced? Because that would require digging. It puzzles me that a cable that is well protected and is housed within such a thick conduit could've gotten damaged.

Regards,

Chris
 
  #4  
Old 11-01-15, 08:02 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
While the light did not need to be on a GFCI circuit now that you know there is a problem you should fix the problem. Is the cable in the conduit NM-b?
 
  #5  
Old 11-01-15, 08:09 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,668
Received 340 Votes on 318 Posts
I had both ends hanging in the air. I used a Fluke multimeter and measured the resistant at the power end between the white and red lines. It read 9.6K ohms. I was expecting to get an OL or open circuit reading.
Your expectations are correct. If neither end is connected...... you have three conductors at both ends. There should be no continuity between any of the wires. If there is..... the wire/cable is bad.
 
  #6  
Old 11-01-15, 08:18 AM
Member
Thread Starter
Join Date: Jun 2015
Location: USA
Posts: 6
Received 0 Votes on 0 Posts
I am not sure about the NM-B one.

The cable has has a light gray protective layer that houses the three wires. The ground terminal does not have any insulation obviously. The other two wires are white and black (sorry I said red in my last post which was a mistake). The white and black wires are quite thick and have one copper connector not multiple small copper lines twisted together.

Regarding the lack of a need for the GFCI for the porch light, I think the light would work fine if I disconnected it from GFCI but that is unsafe I am assuming, correct?

Regards,

Chris
 
  #7  
Old 11-01-15, 08:24 AM
ray2047's Avatar
Group Moderator
Join Date: Mar 2006
Location: USA
Posts: 33,597
Received 13 Votes on 11 Posts
The cable has has a light gray protective layer that houses the three wires.
That is UF-b. That is okay but it needs to be replaced. If this is a complete conduit system* use individual THWN wires. If not complete go back with UF-b cable.

*A complete conduit system runs between two boxes with no section of the run open with no conduit.
 
  #8  
Old 11-01-15, 08:34 AM
PJmax's Avatar
Group Moderator
Join Date: Oct 2012
Location: Northern NJ - USA
Posts: 52,668
Received 340 Votes on 318 Posts
I think the light would work fine if I disconnected it from GFCI but that is unsafe I am assuming, correct?
It may but if you measure slight continuity between the black and white wires now.... it will only get worse as it ages to the point where it burns.
 
  #9  
Old 11-01-15, 10:49 AM
Member
Thread Starter
Join Date: Jun 2015
Location: USA
Posts: 6
Received 0 Votes on 0 Posts
Thank you all. This has been very helpful.

Regards,

Chris
 
  #10  
Old 11-02-15, 12:34 PM
Member
Join Date: Oct 2015
Location: USA
Posts: 110
Received 0 Votes on 0 Posts
The leakage that affects a GFCI should be measured between the ground and the white wire, and between the ground and the black wire. Leakage between the black and white wire will not trip a GFCI.
 
Reply

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Thread Tools
Search this Thread
Display Modes
 
Ask a Question
Question Title:
Description:
Your question will be posted in: