GFCI and Ceiling Fan

Reply

  #1  
Old 11-07-04, 09:15 PM
sdtims
Visiting Guest
Posts: n/a
GFCI and Ceiling Fan

I replaced two ceiling porch light fixtures with celing fans with Light fixtures. I connected the existing light wiring to the fan light wire (blue). I cut a nearby feed to an outside porch outlet which is on a GFCI and spliced in a feed for the fan (all sealed up in a closed metal box). When all the assembly and wiring were done, the lights on the fans worked fine via the switch inside the front door. However when I turned the breaker back on that feeds the GFCI circuit, the GFCI outlet in the garage immediatly tripped. I'm puzzled. One note that I question myself on is this: Since the fan light wiring only offers one wire (blue for hot), I wired the fan's neutral, the neutral from the light switch and the neutral from the GFCI circuit all together. I also connected all the bare copper grounds together along with the green wire from the fan. Could the bonding of the neutral's from two seperate circuits be the cause of the GFCI tripping?
 
Sponsored Links
  #2  
Old 11-07-04, 09:37 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
No matter what you do, you are never going to be able to keep this GFCI from tripping. A GFCI only works right if exactly the same amount of current going out the hot side returns on the neutral side. Because you have parallel hot paths and parallel neutral paths, this is never going to happen.

What you did is bizarre and a code violation too (if any of the electrical boxes are metal). What you need to do to fix this is to replace the black/white/bare cable from the switch to the ceiling with black/red/white/bare cable (and remove that other cable you ran). Let the red wire supply switched power and the black supply unswitched power. In the future, I encourage you to follow standard ways of doing things and not get too creative.
 
  #3  
Old 11-08-04, 04:43 PM
sdtims
Visiting Guest
Posts: n/a
I understand how I have parallel neutral paths since I tied all the neutral's together. Since there is only one neutral wire coming out of the fan that serves both the fan motor and the light, I had to tie the fan's neutral to either the switch feed or the new feed for the fan or both - I chose both and thus created the "parallel neutral". However the black (hot) is not crossed with the other circuit. Seems there would be a way to make this work without your suggested solution. I know that would be the cleanest way, but, given this is a 2 story house, the only way to do that is rip out drywall. Any alternatives?
Also, are you saying it is a code violation to put splices in a sealed "metal" box? If so, does that mean splices should be in a sealed "Plastic" box? I certainly want to do this as right as possible, but I don't understand where I violated the code other than possibly inside the fan box. Thanks for your input.
 
  #4  
Old 11-08-04, 07:18 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Drywall is easy to repair, and dirt cheap.

When only the light is on and not the fan, power to the light comes from the GFCI hot side. The current returns on both of the neutrals. Thus the current returning on the neutral running through the GFCI is sure to be less than the current running out of the hot side. This is sure to trip the GFCI.

If the light was the only issue, you could disconnect the second neutral at the fan and solve the problem. But...

If you disconnect the second neutral, then consider what happens when the fan is on (whether or not the light is also on). Current to power the fan does not come through the GFCI. But the neutral will return through the GFCI. So the current returning on the neutral running through the GFCI is sure to be more than the current flowing out of the hot side. This is sure to trip the GFCI too.

If you leave the second neutral connected, then consider what happens when both the fan and light are on. Current is coming from both hot wires, and returning on both neutral wires. It is just possible that the current going through the GFCI in each direction might be the same. But that's pure luck and will never happen in real life. So the GFCI will trip here too.

This is a lose-lose-lose-lose situation.

It might be possible to remove the GFCI from the equation, if you can do so without removing GFCI protection from something that requires it.

Drywall is easy to repair.
 
  #5  
Old 11-08-04, 08:35 PM
sdtims
Visiting Guest
Posts: n/a
Thanks...I've finally come to understand GFCI operation (e.g. what goes out (black) must come back (white) in equal amounts). My wife isn't going to go for the dry wall tear out - especially since the house is new. I'm assuming my plan would have worked OK and without code violation if I hadn't tapped a GFCI circuit - correct?
I have one other idea that just came to mind that I'd like your opinion on. Since there is only one romex wire coming from the light switch to the light fixture, that tells me that a hot wire is in the light switch box and this circuit just continues on to the light fixture on the neutral and the black goes throught the light switch (or maybe vice versa). Why couldn't I just power both the light and the fan off the GFCI circuit by making the romex coming from the light switch into a "switch loop" (don't know if that's the right term). To do this (I believe), I would disconnect the neutral in the light switch box from the wire nut where it's tied to the feeder circuit and disconnect the black hot wire from the switch (or it may be vice versa) cap it and then connect the white to the switch, and feed the hot to the switch from the GFCI hot ( or neutral - don't know which is proper - switching the hot or neutral).
Two questions...(1) would this work? and, (2) would this violate any code?

Also, I'm still puzzled about your reference in your first post to the "code violation (especially if the boxes are metal)". Should they have been plastic?
Thanks, I appreciate your help and hope I haven't been too aggravating! Best Regards, Steve
 
  #6  
Old 11-08-04, 10:11 PM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Your idea won't work. Not even close.

Chance are pretty good that you could put in the new cable from the switch to the ceiling without any drywall damage anyway. Hard to tell without looking at it.

The code violation is complicated and has to do with heat buildup in the metal box induced by the magnetic field created by the uneven current flows.
 
  #7  
Old 11-09-04, 05:36 AM
Member
Join Date: Sep 2003
Location: Central New York State
Posts: 13,973
Received 0 Votes on 0 Posts
John,

I believe that his idea would work. His terminology is off, but I see no reason (electrically) why he can't pull power from the porch circuit, and then use the existing wire to the switch as a switch loop for the light.

sdtims,

It is always the hot wire that is switched. The neutral wire is never (or at least it should never) be switched on a branch circuit.
 
  #8  
Old 11-09-04, 07:31 AM
Member
Join Date: Sep 2000
Location: United States
Posts: 18,497
Received 0 Votes on 0 Posts
Thanks Bob. You saw something I didn't. I stand corrected.
 
  #9  
Old 11-09-04, 05:39 PM
sdtims
Visiting Guest
Posts: n/a
Thanks to both of you, John and Bob...This will be a simple fix and there certainly won't be too much load on the GFCI circuit as nothing is ever plugged into it except sometimes a radio in the garage. Hopefully my assumption about what is in the switch box is correct, but I can't imagine it can be any other way. Thanks again. Steve
 
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: