Can A TVS help on a 120AC circuit?

I have this exact issue with the gfi on my bath fan. the fan / light is in an enclosed shower, and by code had to be gfi protected. it always trips when my hand is wet and i contact the screw on the switch plate and the switch simultaneously. i never really gave it much though other than its a pain in the *** 

 btw the switch is OUTSIDE the shower!

ohh, and there is a separate switch for the fan and the light. it doesnt seem to matter  if the fan is on or or not when this happens. ill be interested in what some of the engineers have to say about this

I have this same exact issue, and the GFI is the type located in the main panel... which means a hike to the basement to reset it.

A TVS is for clamping over-voltages... the GFI trips on a current imbalance(fault path detection) regardless of the voltage, so I do not believe a TVS installation would make a difference.

Thanks for the input Ryan and Rob. At lest I know that I'm not the only one in the world who has seen this.

But Ryan what you said about how the interuption occures when you touch the wall switch with wet hands worries me a little. As far as I know there should never be a ground fault on a switch. The GFI is for protection when things goes wrong and to me that sounds wrong. I would open that switch box up to see if there is a pinched wire inside. That never happens when we use the shower at our house and the fan is over our tub as well. 

But, back to GFI application 101, can someone out there give us a fix or explanation for this?

It has been a long time (12 years) since I wired my house, but unless the code has changed, the light and the fan should not be wired to the protected side of the GFI. None of the ones in my home are, and I have no such problems.

Those devices are already grounded and should be powered directly.

There is no real safety advantage having the light and fan powered from the protected side, and you have discovered the disadvantage.

The GFI is intended to protect outlets in wet or damp locations only.  In the case of multiple outlets, the GFI is the first in the string, and the others can be daisy chained from the protected side.

I think there is a bad ground on the circuit. A wet area circuit can rust out connections and create a false circuit through the metal parts. That is why there are GFI circuit required in wet areas. Some defrost circuits in refers will also trip GFI , a building inspector told me.  That is why there are no whole house GFI required.  

Mario, how old is the house?

Hi "Train Yard" It's not the grounding, if it was I would have the same problem with othe devices. I think Elliot hit the nail on the head, though I would have to check the electrical codes.

Thanks Mario, and do please check the code. I'm not an electrician, just a very experienced DIYer.

The house was built in 1927, but it was totally redone in the eighties by me. The electrical was completely reworked at the time. It was also inspected three times for the bank as well as electricians and plumbers who are friends.

Believe me guys if they found anything out of order they would of been all over me. No critic is as loud as a friend with a few beers in them.

In any case the beer paid off because I got alot of good advice.

In fact I spoke to a couple of electricians about this issue and the one who dose commercial work never ran into this. The other who dose alot of residential work told me what Elliot said. But, did not feel good about a light fixture in a shower area without a GFI on it, so he said to live with it. He said at lest you know the GFI works.

I'm not an electrician but it occurs to me that over time moisture can get into the switch box and cause a film to develop on the switch housing causing a small current leakage path to the grounded mounting screws. Should this happen the surge that occurs when the fan is turned off may be suficient to bridge the gap with enough power to trip the GFI. The solution would be to replace the switch with a good quality one and install a seal gasket behind the cover plate. I am of the opinion that any time a GFI trips something needs to be investigated.

big boy, the code is updated every 3 years or so. now in pa were under the UCC code.

the addition that this gfi is in is less than 2 years old. I build it my self. the new code requires light / fans over tubs and in showers to be on the protected side of a gfi. luckly, my shower light is on its own gfi, so its not a "black out" when it trips. I spent the last eight years building (and living in at the same time) this house. i have been meaning to take the swithces out to investigate, but I'm still saturated from spending the last eight years of weekends and evenings working on this house. its been all i can do to finish the basement these last few months for my train layout. I used to enjoy going to home depot or lowes and "look around" now i get a headache just driving by the place!

Hi "HOSO&NZ", I thought of the same thing so when I installed the new fan I also changed the switch and double checked the grounding, with power off I went down to the main panel and disconnected the white wire and ground at the panel and connected them together. I then went up to the fan switch and took an ohms reading, and I had continuity. Of course if I set the meter to RX10K I saw a small resistance due to the fifty foot loop of the #12 Romex. I then reconnected to the panel and tightend every screw in the panel, I do this every year or two just as a Gee-Wiz pecaution. We must also remember that this issue only shows up when I shut the fan off every so often. It dose not happen with any other devise, not my drills, hair dryer, vacuum cleaner, ect, ect.

Boy Ryan I know what you are talking about. But the sad thruth of the home owner is that when you do your own work by the time we complete everything we have to go back to step one and start replacing the things that wore out.

Well, if that's the code, that's the code. Personally, I don't agree with it. Nowhere else in the home, are switches and devices GFI protected (unless that's changed too). I guess I don't understand what that rule is supposed to protect you from. GFI is a proven life saver, but in this application, I don't see the the hazard.

Kitchens now require two GFI circuits for counter level outlets.  The outlets are to alternate from one GFI to the other as you go down the length of the counter(s).

Outdoor outlets are required to be on a GFI also, our builder put them on the bathroom circuit.  If I trip it outside, the bathroom occupants are in the dark.

gg1man,

The best solution that I can come up with to help you is to replace the GFI unit now!

I had a GFI in the bathroom go bad and I had to replace it after almost 14 years. The GFI tripped with a hairdryer or electric drill.

If you had a pinched wire in the outlet box your main breaker would have thrown, not the GFI.

Speaking of new electric code; a ground wire is required now in EMT(elecrical metallic tubing, thin-wall conduit) in certain cases. I have seen this with newer air conditioning work, could be commercial application only.

Lee F.

Rob, that's crazy that your outdoor protection is tied to your bathroom. GFI outlets aren't that expensive. I haven't priced them in a while, but they can't be much over $10. 

I actually have 3 in my kitchen, but they don't alternate. Each serves a particular section (I have a large kitchen). The inspector made me add one to a "dry" area, just because it was in the kitchen.

I have an outlet below my cooktop which powers the ignitor for the gas burners and the exhaust fan. One day it wasn't working. It took me a while to figure out that the GFI had popped. Because it was out of sight, I had forgotten it was on the protected side. It must have been a thunder storm that popped it. Otherwise everything stays on just fine.

My outdoor outlets are all protected, including the one in the garage. Because they are so far away from each other, they are all on different circuits. Two are simple GFI outlets. The third one that serves the backyard is actually located inside, with a protected outlet tied to it on the exterior.

Ours is an integral-to-the-breaker type, in the main cabinet.

It is odd anyway, we have a 300 amp panel, so it's not like there isn't room for a dedicated circuit.

Another thing about GFI outlets and this is very important; if the nuetral side has a break, any load to the hot side it automatically pops the GFI. I wired up an outdoor GFI from a breaker box, circuit breaker style GFI, and I used the nueteral from the main box instead of going with the nuetral from the GFI breaker, talk about frustration. Had to consult a master electrician at work about my problem, hooked the nuetral from the breaker and everything worked fine.

Lee F.

Hi Lee, changing the GFI can't hurt, I think I will do that this weekend.

As for the pinched wire, I seen them cause what I call a high resistive short. In other words there is no direct path to ground, or return but the insulation is compromised to the point of the wire starting to get a little warm.

But, that said my GFI is working fine in all respects other then the exhaust fan. I think it's Ryan that has a wiring issue. None the less your suggestion is sound and I will run with it on Sunday after church.

Thanks.

Mario, I wired it my self, and even though I never finished my EE degree, I do have  an associate degree in electrical technologies. 

I think my issue is a pinched wire, a "high resistance" short as you called it, and the humidity and the dampness of my hand when i get out of the shower is enough to complete the short to complete the Ground Fault.   perhaps, after my 1000 and 1 chores this weekend are done ill take a looksey at it.  

Other than the fact that this is a complete pain to deal with, this thread really has me wondering about it.......  to the point i used the other shower tonight....

Or, should I try to change the GFI?  Probably, GFIs can age out within 5 years depending on the loads.

Retired Master Electrician

+1 exactly. This is not a spike problem. A GFI protects against currents leaking from the hot wire or neutral wire to earth ground. A bathroom fan housing is (or should be) connected to earth ground. If the insulation starts to break down or moisture carries current to ground the GFI trips. The problem is in the fan unit or close by wiring most likely. You can pull it out and clean it or just replace the fan unit.

Pete

Hi Pete, good point but I changed the fan, twice. I had a Newton fan in it for about seven years and it caused the GFI to tripduring shut off periodically. That fan faild so I changed it out about a month ago with a new Newton fan of the same model type this past May and it did the same thing I mentioned above.

 I then removed the Newton fan and installed an Inline booster fan in it's place and it did the same thing. A note that may be of interest is that I put the booster fan in line with the new Newton fan and the GFI tripped every other time I turned it off. Obviously I removed the Newton fan because of the noise and left the booster in-line fan in place, but added a 120 VAC neon indicator lamp at the switch that seamed to improve the frequency count of the tripping, in other words it tripps less often.

From what I can see the problem has to do with the AC motors used in these fans. It probably has something to do with moisture because as I stated above I have had other AC appliances on this GFI with no problems at all and it only occures when there is moisture build-up in the bathroom. Come to think of it I once had some water get on a drill that was plugged into the GFI and it did it's job by tripping.

It's not the grounding and I really don't think it's the GFI but I will change it just to be on the safe side.

But, I thank all for the input because some place out there is a fix for this question. I was hoping that this was a common trouble and as can be seen by other post I am not unique with this issue. 

Maybe my next step is a letter to Newton to find out what they think. But. I'm sure I will probably get the "pat" answer to change the GFI so again that's another reason to R&R it before going forward.

Mario, What you might want to try is:

Turn off the breaker at the distribution panel.

Disconnect the wires at the GFI that go to the fan.

Take an ohmmeter and read between hot and ground and also neutral and ground.

It should read close to infinity or at least a few megohms.

If it reads below one megohm then you have a leak path to ground. It could be the fan or the wiring close to the fan. It only takes a few microamps of current to trip a GFI.

At least you will know if its the light, fan or wiring and be able to go from there.

Pete

Hi Pete, that's a very good point because I'm using the original celling housing for the light assembly over the tub.  Even though I rewired the thing it's not a bad idea to check for what you said. Actually it sounds like fun, who knows I might learn something.