GFI question

[jmattero]

I recently upgraded the electric in a bathroom in a recently acquired rental property, by changing the old 3-prong outlet to a GFI. This was installed in a 3 gang box. The other two compartments were for switches that controlled the two bathroom lights (one over the sink, and one over the tub). In any case, in an effort to GFI protect the lights, I connected their feeds together and pigtailed that to the LOAD side of the GFI. The incoming hot also supplies other fixtures (hall and bedroom lights), so I ran a pigtail from that incoming hot to the LINE side of the GFI, and did the same with the neutrals. I should note that there is only ONE circuit in this box.

After hooking it up this way, I tested the GFI, and the bathroom lights, and everything worked correctly.

However, the next day, I switched on the hall light (3-way switch), and the bathroom GFI popped. I reset it, and then turned on the bedroom light (not a 3 way switch), and the GFI popped again. Obviously, the GFI is sensing an unbalance, but I really don't understand why.

I went back into the 3 gang box, and rewired it such that the GFI was the end of the run, and the switches were removed from the LOAD side of the GFI, and simply wired to the incoming hot. After that, everything works fine.

I am simply trying to figure out why this is happening. Can you NOT have a switched luminaire downstream from a GFI? Why doesn't this happen if I plug a light into a downstream outlet in the bedroom, and then turn on that light switch? Again, I do not have a problem, I am simply trying to educate myself, to get a better understanding.

Thanks in advance.

Jeff

 

[hurk27]

Sounds like the lights are fed fron a neutral that is wired ahead of the GFCI, for this to work all conductors on the load side must feed through the GFCI this includs the neutrals, if the neutrals are fed to the light first then this can't be done. the GFCI work by senseing the current leaving it on the hot and returning on the neutral if both are not connected to the GFCI then it only see the current leaving on the hot and thinks it is going some where else.

 

[Dennis Alwon]

It is hard to tell but obviously the neutrals were not returning thru the gfci. Perhaps there is a box somewhere in the attic where the neutrals are all tied together so that the gfci sees an imbalance. Things are not always as they seem esp. when there are many possible explanations.

 

[jmattero]

Thanks

Thanks

Huck & Dennis:
In thinking about it, I think you are both correct, and it makes sense.

In the original hookup of the GFI, I simply ran a pigtail from the neutrals that were tied together in the box, and put that pigtail on the LINE side of the GFI. For the hots, there were two unidentified blacks (fed downstream probably to hall and bedroom), and the incoming hot. I tied these three together with a pigtail, and connected that pigtail to the LINE side of the GFI. I then made a new pigtail (black) from the LOAD side of the GFI to the two pigtails that supply the switches.

If I understand you both correctly, I could have had the bathroom switches be downstream of the GFI (therefore protected) by seperating all of the hots and neutrals in the 3 gang box, pigtailing the supply hot and supply neutral to the LINE side of the GFI, and then pigtailing the hot and neutrals that supply the bathroom switches. The unidentified downstream feeds that likely went to the Hall and bedroom would NOT go through the GFI, and therefore, the GFI would not pop when I turned on those switches.

Is my understanding correct?

Thanks again.

Jeff

 

[Dennis Alwon]

What I am saying is that on the load side of the gfci perhaps somewhere the neutral is connected to yet another neutral back to the panel. This would give the current 2 paths. One thru the gfci and the other directly back to the panel. If that is the case then the gfci reads an imbalance ad will trip. The hall lights may be connected similarly thru the gfci. Upstream current should not affect the load side of the gfci so there must be something from those circuits that is going thru the gfci.

 

[jmattero]

Dennis:
Thanks, I understand your point. By the way, I love the pictures that scroll. I have all of those people on my MP-3 player!!!

Jeff

 

[slalom skier]

What type of lamps are you using?

 

[jmattero]

Lamps being used

Lamps being used

The lamps are one hi-hat (sealed) over the tub, and a 3 light bar over the medicine cabinet.

 

[Dennis Alwon]

The lamps are one hi-hat (sealed) over the tub, and a 3 light bar over the medicine cabinet.

Have you solved the problem?

 

[jmattero]

Dennis - Yes, but the way I solved it was to make the GFI the end of the run (wires connected to the LINE side only), and I wired the switches for the lights ahead of the GFI. This solved the problem inthat everything worked correctly, but the switches and lights are not GFI protected. Not a big deal, but I just didn't understand WHY I was having the problem.

Thanks.

 

[slalom skier]

Are you using any fluorescent bulbs?

 

[Dennis Alwon]

Well you will never know for sure unless you go back and find it. Obviously something is amiss and it is possible a gaussmeter would help eliminate some problems.

 

[jmattero]

Dennis:
I own three houses on this street, and have had a similar problem in all of them. These houses were originally wired without a ground wire. In an effort to give the tenants three prong receptacles, rather than have them use 3 prong to 2 prong adapters. I placed GFI receptacles in each of the bedrooms, and labeled them as UNGROUNDED. The problem was, when I turned on the 3 way switch controlling the hall light, the GFI's would pop. I then pulled out the GFI's and replaced them with 2 prong receptacles. Some of these receptacles were on one circuit, and some were on another. I didn't have time to do a thorough investigation, but what I did find out some things which I think were a problem. To make it a little clearer, assume that the 3 way switch was on circuit #1 and the bedroom duplexes were on circuit #2. When the original electrician wired the 3 way switch (circuit #1) he used the neutral that was part of circuit #2. That is how I believe the GFI is sensing a fault, since there are two paths going back to the panel. Again, I didn't have enough time to do a thorough investigation, since the tenant was moving in. However, since it had worked for 50+ years without a problem, I left things the way they were originally wired.

It's funny, but I have seen a similar wiring scheme in other homes I have that were built in the late 60's and early 70's. In these homes there is a 3 way switch at the top of the basement stairs controlling the basment lights. In that box, there are two circuits. To be clear, I call the first switch in the run (the one that is supplied with the hot directly from the panel) the MASTER switch. I always hook the incoming hot to the Common terminal of the MASTER switch. I call the other 3-way switch the SLAVE switch, and the black coming from the luminaire is hooked to the common terminal of the SLAVE switch. If I were the one who ran the wires, I would have used 14/3 between these switches. However, in these houses, they always seemed to use 14/2. They would then use the true neutral from circuit #2 as the neutral for circuit #1 (ie., they would jump the neutrals between these two circuits), and use the white wire that SHOULD have been the neutral for circuit #1 as a traveler for the 3 way switch.

I am not sure if you will be able to understand clearly what I have tried to describe, but, if you do, was that EVER allowed by the code? To me that type of connection scheme seems dangerous, since when you have circuit #2 turned off, there is still current going over the Circuit #2 neutral (coming from circuit #1). Was this ever Code correct???

slalom - no, none of the bulbs are flourescent. Again, this problem is solved, but thanks for your input.

 

[chris kennedy]

I am not sure if you will be able to understand clearly what I have tried to describe, but, if you do, was that EVER allowed by the code? To me that type of connection scheme seems dangerous, since when you have circuit #2 turned off, there is still current going over the Circuit #2 neutral (coming from circuit #1). Was this ever Code correct???

Yeah, its called a MWBC. They are so dangerous 210.4(B) had to be added to the code.