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-   -   GFCI intermittent nuisance trips (http://www.diychatroom.com/f18/gfci-intermittent-nuisance-trips-26245/)

jejm1975 09-03-2008 10:05 PM

GFCI intermittent nuisance trips
 
Okay, first off I would like to state that I am not a electrician, an electronic technician perhaps, but when it comes to AC I am as lost as a ball in tall grass. I would also like to state that I believe that I understand the fundamentals of a GFCI breaker, it is looking for a difference in current on the common (neutral, white) and the hot (power, black) wires and a variance over 5 milliamperes will cause the GFCI to trip. This is usually a result from a ground fault, which may or may not include the actual earth ground, but is usually a faulty connection somewhere in the common run, caused by moisture or even a bad spot in the insulation due to inadequate precautions while installing (usually). The reason that I wanted to put all that first is due to my conducting several tedious hours researching my problem and discovering that most of the replies covered to some degree and on occasion disputed the above mentioned items, but what you see is what I have come to be most correct. I have not found any scenarios that were close enough to my situation that I felt comfortable in proceeding with any corrective actions.

Whew! Okay, my dad and I recently built a screened in porch on the back of his mobile home. This mobile home is over twenty years old, but well maintained and no major issues. After I did the structural engineering portion and designed the decking and roof system, my dad assisted in the construction. He decided to wire three electrical outlets, a ceiling fan and four dual four foot fluorescent lights. Now he has done some DIY wiring in the past for his shop located adjacent to the mobile home. He checked the outlets with one of those three pronged testers, two amber lights indicating correct wiring, polarity okay and good ground. The ceiling fan works fine, as do the outlets. The porch is wired to a male three pronged standard plug and plugged into an outlet that is wired on a breaker in the main junction box. He decided to use the plug setup until he was confident there were not wiring issues, then he intends to hard wire the porch to a breaker inside the main junction box.

Now here is where it gets mind boggling. He has a GFCI breaker inside the mobile home that is wired to both bathrooms and the external outlet at the far end of the house. Well it seems that the GFCI trips on a whim. We replaced the outlet outside thinking that there may be a moisture problem, but the problem persisted. By happen-chance, I discovered that the GFCI breaker is tripping only when the fluorescent lights are switched on AND not every time. The lamps have electric start ballasts, for low temperature operation, therefore I hypothesised that perhaps there is some inductance during the initial powering up of the lights, even though they are on a different circuit. I have been able to reliably reproduce this anomaly by having all four lights switched on at their individual factory pull switches and then flipping the wall switch that he wired them to. He mistakenly got two three-way switches, one for the lights and one for the fan. He has 3-14 romex coming into the porch, wired to an outlet then split with one run for the other two outlets and the other run split again with one run going to the switch and the celing fan. The other run goes to the switch, then he split the run again, one for one side of the porch lights and the other run for the other side with two light fixtures with two tubes each for a total of four 40W four foot lights off of each run. Well I think I have successfully convoluted this topic to the point to where I may need psychotherapy. I thank any and all for taking the time to read this far and I will be anxiously be anticipating comments. God bless. ~~Joey~~

chris75 09-03-2008 10:10 PM

I hate DIY GFI problems, way to easy for to many mistakes, I would meg the wire and find the fault.

Stubbie 09-03-2008 11:12 PM

Quote:

He has 3-14 romex coming into the porch, wired to an outlet then split with one run for the other two outlets and the other run split again with one run going to the switch and the celing fan. The other run goes to the switch, then he split the run again, one for one side of the porch lights and the other run for the other side with two light fixtures with two tubes each for a total of four 40W four foot lights off of each run. Well I think I have successfully convoluted this topic to the point to where I may need psychotherapy. I thank any and all for taking the time to read this far and I will be anxiously be anticipating comments.


Hello Joey

A couple comments.. Fluorescents are often the cause of intermittant tripping gfci's. However the gfci breaker is not part of the circuit from which the porch lighting is supplied. I'm assuming that other appliances can be plugged into this outlet the porch is supplied from and the gfci will not trip.....only trips when you turn on the porch fluorescents? ..and you are positive this gfci breaker is not part of the outlet the porch is plugged into?







jejm1975 09-04-2008 12:57 AM

Quote:

Originally Posted by Stubbie (Post 154791)

Hello Joey

A couple comments.. Fluorescent are often the cause of intermittent tripping gfci's. However the gfci breaker is not part of the circuit from which the porch lighting is supplied. I'm assuming that other appliances can be plugged into this outlet the porch is supplied from and the gfci will not trip.....only trips when you turn on the porch fluorescents? ..and you are positive this gfci breaker is not part of the outlet the porch is plugged into?







What thank both you and Chris for your interest. Yes I can unequivocally claim that they are on separate circuits (which is what is killing me) due to the fact that when the GFCI breaker trips, the lights on the porch continue to work. Now ain't that a kick in the "shorts". Please overlook my crude humor, just trying to remain sane. Again thank you all for any suggestions, I am fresh out of ideas. I can use one like and switch it on and off by way of the wally switch and not get a recurrence each time, but after several attempts it does trip. I have scoured both this site and google, and you guys seem to be the most popular search results, not to mention that for the majority, everyone here seems to get along, rather than stiffeling my attempts to resolve this with altercations on about certain "theories". I just want to eliminate any safety concerns, however learning of what the culprit is would be a bonus. I just don't my dad to replace the GFCI breaker in the house box with a standard breaker just to wake up to a smoldering fire due to cutting corners. Preventing a problem is far safer and cheaper, so I guess I need some enlightenment with you help. Thanx,, Joey

petey_c 09-04-2008 05:52 AM

jejm1975, Hmm, seems like you've got yourself quite the problem. I can't say why the GFCI is tripping. What you could do is replace the GFCI breaker with a regular breaker and change the first outlet in the "stream" to a GFI outlet; hot pair (from the panel) to the the line side and the remainder of the circuit to the load side. See if that "solves" your problem. Is the GCFI and the fluor. lights on the same bus in the panel? Perhaps some sort of inductance there causing the breaker to trip. I'm not an EE, just an ET and electrician. Like they used to say about frequency modulation, it's "FM" feakin' magic....

BigJimmy 09-04-2008 09:46 AM

Since this is a GFCI breaker, the problem could simply be an overcurrent issue.

While the OP's understanding of GFCI's seems to be solid, I, like Chris, find the GFCI issues posted herein to be somewhat annoying. With GF's, there can be a zillion reasons for the tripping and it's very tough to shoot this type of trouble online.

BTW, I have several 32W 2-bulb FL fixtures in my basement which are powered from a GFCI breaker (and yes, I understand that it is not required however when I installed the lights, it was the only type of breaker that I had on hand). 2 years later, I have not suffered one nuisance trip.

Done

daxinarian 09-04-2008 11:08 AM

Is it possible that there is a crossed neutral or two neutral paths for the florescent light fixture? Even though the light is fed from the non GFCI circuit, if some of the juice can get to the neutral wire on the GFCI circuit it will sense an imbalance and trip.

About the only other thing I can think of is if there is a "ground loop" (or in this case a Neutral or Hot loop). If you have a loop of wire it can be susceptible to nearby electrical interference (transformers intentionally use this to step up/down voltage). The Florescent light may induce a small current/voltage in an adjacent loop and if that loop happens to be on the GFCI circuit... bang there goes the circuit.

My money would be on the first one, but the solution to both is the same: Make sure there is one and only one path for the electricity to take on all circuits at any time.

jejm1975 09-04-2008 11:15 AM

Quote:

Originally Posted by petey_c (Post 154830)
Is the GCFI and the fluor. lights on the same bus in the panel? Perhaps some sort of inductance there causing the breaker to trip. I'm not an EE, just an ET and electrician. Like they used to say about frequency modulation, it's "FM" feakin' magic....


Thanks petey for the assistance. To answer your inquiry about the bus, no there are not even in the same panel, again that is what is really warping my mind. What I am afraid of is that this ghost I am chasing is an indication of something more notorious lurking beneath. As they say, GFCI's generally trip because they are doing their job. Dad thinks that perhaps the porch doesn't have a good enough ground without being hardwired. I suggested that he should check the connections to the buses to eliminate that. I just can't get how something on a totally different circuit, in a different panel can trip that GFCI breaker.:wallbash::cursing::help:

Winchester 09-04-2008 11:47 AM

I'm not a professional but trying to follow along here but when did multiple panels come into play? Can't believe there is more than one for a mobil home. Thought this was plugged into an existing circuit of the main panel??

Stubbie 09-04-2008 12:00 PM

Ok it would seem to me that the fluorescents are causing the problem like it or not. IMO the problem has to be emi/rf induced into the electrical system from the ballasts of the light fixtures. You might check to see if one of the lights is slow to start (light) on occassion. This may be the source of the intermittant tripping gfci.
A discussion on emi and rf nuisance tripping would entail many pages so I think best to isolate the problem to the fluorescents. Asuming that all current carriers connections are proper and isolated from grounded metal and each other. I doubt you have a fire hazard assuming you agree that the wiring is correct for the porch. My suggestion would be to run an extension cord from other outlets and plug the porch into those and see if it still trips that gfci. I would include the bathroom receptacle on the gfci circuit. I would also be sure this gfci breaker is not old school and is of the newer type with improved circuitry for interference from emi/rf and the fluorescent ballasts should have THD of less than 10%. Electronic ballasts are the most unstable and can emit rf in large doses if not shielded properly. You will see this in the cheapo light fixtures. My understanding is that these are no longer UL listed so probably is not your problem.You might even have to resort to new fixtures that are incandescent or better quality magnetic ballast fluorescents if the ones you have now a cheapos.

HouseHelper 09-04-2008 01:20 PM

Can you describe how the fluorescent lights are wired?

You stated the porch was wired with receptacles, ceiling fan, and fluorescent lights, and that the porch is for now powered by using plug and cord at a GFCI protected outside receptacle. You also stated you used 14/3 to do this. I am having a hard time figuring out how this is wired, and how the lights could keep working in this scenario.

Stubbie 09-04-2008 01:39 PM

Yeah that's a good point...I considered that he meant 14/2 with ground.

jejm1975 09-04-2008 01:47 PM

Quote:

Originally Posted by daxinarian (Post 154893)
Is it possible that there is a crossed neutral or two neutral paths for the florescent light fixture? Even though the light is fed from the non GFCI circuit, if some of the juice can get to the neutral wire on the GFCI circuit it will sense an imbalance and trip.

About the only other thing I can think of is if there is a "ground loop" (or in this case a Neutral or Hot loop). If you have a loop of wire it can be susceptible to nearby electrical interference (transformers intentionally use this to step up/down voltage). The Florescent light may induce a small current/voltage in an adjacent loop and if that loop happens to be on the GFCI circuit... bang there goes the circuit.

My money would be on the first one, but the solution to both is the same: Make sure there is one and only one path for the electricity to take on all circuits at any time.

Thanx dax. Sounds good, but I kinda got lost in the "loop" portion, so I have attempted to construct a diagram http://farm4.static.flickr.com/3069/...8bbf6a.jpg?v=0illustrating how everything is laid out. Please excuse my elementary drawing skills, but I think it may prove to be a good reference for you to direct me in the correct direction. Thanks ~~Joey~~

jejm1975 09-04-2008 02:01 PM

Okay here are some visual aids, because I know that I am probaly not explaining all of this correctly.

http://farm4.static.flickr.com/3069/...8bbf6a.jpg?v=0

This is a rudimentary drawing depicting the run, color coded for your convenience.

http://farm4.static.flickr.com/3148/...bef1f7.jpg?v=0

This is the external panel with the utility MAIN comming in. Porch is plugged into the duplex receptacle, which is on it's own breaker.

http://farm4.static.flickr.com/3037/...e74b9b.jpg?v=0

This is where the line comes into the porch, runs through this duplex receptacle.

http://farm4.static.flickr.com/3274/...265d65.jpg?v=0

The line then runs to a splice, where on run feeds the other two duplex receptacles and the other run goes to a junction box.

http://farm4.static.flickr.com/3008/...1b394d.jpg?v=0

From the junction box, the line is split again, one run to supply the 3-way switch (wired as a single pole) for the ceiling fan.

http://farm4.static.flickr.com/3057/...5d7340.jpg?v=0

The other run supplies the 3-way switch (wired as a single pole) for the lights.

http://farm4.static.flickr.com/3244/...b6a448.jpg?v=0

Here you can not see the splice from the switch, but is where the line splits to each side of the porch.

http://farm4.static.flickr.com/3251/...c964a8.jpg?v=0

Each pair of lights is hardwired inside the junction box. The run from the junction box is spliced to supply each side of the porch.

jejm1975 09-04-2008 02:04 PM

Quote:

Originally Posted by Winchester (Post 154908)
I'm not a professional but trying to follow along here but when did multiple panels come into play? Can't believe there is more than one for a mobil home. Thought this was plugged into an existing circuit of the main panel??


Yeah I know my description goes around the world, to clarify, there is a Main panel located outside where the utility feed comes in from the street and that has breakers and lines going to a duplex receptacle, the shop, the AC and heating strips, then the main goes into the mobile home to the wiring panel for the house.


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