GFCI tripping issue on house

[DuneElliot]

I am sooooo confused. I don't suppose any electrical experts will be thru Wyoming before the beginning of June or after mid July?

[Kirk W]

9 hours ago, DuneElliot said:

I am sooooo confused. 

1

Some of our well-meaning experts here have a real flair for making a simple problem more complicated. Does it really matter how your GFCI works? To the average user, the device either works or it does not and even these technical experts are not going to repair them.  If you really want to know how the device works, I suggest that you ignore the debate here and read this explanation from "electrical safety .org". 

What we really need to determine is the cause of your problem and not the theory behind it. Do you happen to have another electric heater? If you do I'd try everything you have done before but with another heater. The fact that it happens when you set the heater to high could be the answer as the circuitry changes when you do so. See if it will run on low when connected in all configurations as it may well be that the problem is in the heater it's self. 

I am sending you a PM with a bit more.

 

[Chalkie]

Let me jump in here and relate my story, which could easily be OP's story. 

Last year we got home from an extended trip and plugged in as we always do. Immediately the GFCI on the house tripped out. In our case, we have a 30 amp RV plug on the side of the house with an adapter to 50 amp on the trailer end of a cord. That plug in is in reality no more than 20 amps as it is fed (for now) off of a 20 amp GFCI protected circuit. This might not be code but it works for us to keep the RV batteries charged up.

After testing the cord with a meter, and replacing the GFCI with a spare the problem was still there. I was scratching my head as the EMS had never reported any problems with anything along the way and nothing ever malfunctioned in the RV. 

I turned off the main breaker in the RV, plugged in and all was fine. I started adding in one circuit at a time until the GFCI tripped out. Only it didn't at the time. I shrugged and thought what the heck. A day later, it was tripped again. I went through the drill and this time a particular circuit tripped the GFCI. I thought I was getting closer and although the only thing plugged into that circuit was a couple of table lamps so I unplugged those and tried again. Tripped once more.

I thought it might have been wiring jarred loose at this point so I decided to start pulling outlets from their boxes to check. Fortunately, in terms of time saving I started at the back wall of the RV. The first one I pulled had a lot of dust in it. Blew it out with canned air, checked the connections and but it back in. Next plug, same thing. For grins I turned on the circuit and it did not trip. 

So here is what I found. We live in a normally very low humidity area. On looking back, the days it was tripping the humidity was up. That, combined with the the dust in the outlet boxes was what was tripping the GFCI. 

Hope my story helps you track down your problem. 

[oldjohnt]

Dune, I don't think you're confused, it sounds like you are on the right track as far as systematic troubleshooting is concerned. You have done a good job so far. Lets try the KISS approach.

1) Okay, if that oil filled heater is tripping a GFCI and if its a plug in type device you can take outside the RV, take and plug it into a household GFCI WITH ITS OWN CORD NO EXTENSIONS INVOLVED on high AND SEE IF IT STILL TRIPS???????????? If so, heater is likely defective. I have seen space heaters go bad and trip a GFCI. They can have suspended heat strips which due to high current and heat can develop a ground fault and their heat selector switches aren't super quality and can develop a leak.  

2) If it DOES NOT trip inside, but DOES TRIP when plugged into a GFCI in the RV, the RV's GFCI may be bad.

Another difference is the RV receptacle. Is it an actual GFCI itself, they have the small push to test and reset buttons maybe a small indicator light??? Or is it a standard receptacle that's still GFCI protected because its on a circuit that's downstream of a normal real GFCI located perhaps in the bathroom or kitchen???

FWIW Kirk is 100% CORRECT, I agree. The problem is simple so don't overthink and over complicate this and get all wrapped up and confused with theory. Its EITHER the heater is defective orrrrrrrrrrrrrrrrrrrrr a GFCI receptacle is defective orrrrrrrrrrrrrrrrrrrrrrr there's a leak in branch circuit wiring leading to the receptacle into which its plugged (moisture or bad connections)  PROVIDED THAT that circuit is monitored because it passes through an upstream GFCI. 

Get rid of any extension cords,,,,,,,,,,,,,,try the heater in a household GFCI other then in the RV,,,,,,,,,,,,If it trips there its likely bad, if not then suspect the RV GFCI or GFCI protected circuitry leading to where the heater is plugged in. As I said previously, a GFCI ONLY monitors devices plugged into it or devices on a circuit that are fed off the GFCI from its LOAD side terminals. In an RV you can find a regular outlet that's still GFCI protected because another GFCI like in the bath or kitchen serves that circuit and receptacle. In that situation (heater plugged into regular receptacle that's fed from a regular GFCI) if the heater trips the GFCI (like in kitchen or bath) IT MAY BE THE CIRCUIT THATS AT FAULT INSTEAD OF THE HEATER.

KEEP IT SIMPLE, DONT GET CONFUSED ABOUY THEORY, TRY THE HEATER WITH NO CORD IN A HOME GFCI, IF IT STILL TRIPS I SUSPECT THE HEATER WHICH MOISTURE OR HIGH HUMIDITY OR POOR QUALITY OR AGING CAN CAUSE.

 Post back your results and any questions and I will try to help you. Hope this helps and doesn't confuse lol

PS yours would NOT be the first portable heater I've seen that trips a GFCI, and moisture and humidity inside an RV can also wreak havoc on GFCI circuitry. Gotta be one or the other right lol  

John T  

 

 

[DuneElliot]

Okay, less confused now.

We just got more moisture (kinda fed up of snow and rain) so will do some more troubleshooting when it clears up. I'll do some outlet cleaning and checking, and also test the heater elsewhere but I did try a different heater (make, model and style) and had the same issue.

What leads me to believe that it is not the RV wiring itself is that the GFCI outlet tripped when the heater was plugged directly into the extension cord and turned from low up to high.

[oldjohnt]

21 minutes ago, DuneElliot said:

Okay, less confused now.

  Congratulations. Glad we helped. KISS  You're getting there for sure.

 John T

[oldjohnt]

A BIG THANK YOU TO KIRK,

I just had the opportunity to look at the informative GFCI link you were so kind to post above:

https://www.safeelectricity.org/information-center/library-of-articles/55-home-safety/317-ground-fault-circuit-interrupters-gfcis

and was happy to see IT DESCRIBED HOW A GFCI WORKS WHICH IS EXACTLY AS I RECALLED AND EXPLAINED IN MY POST ABOVE

It stated  "The GFCI will “sense” the difference in the amount of electricity flowing into (the Hot) the circuit to that flowing out (the Neutral)"   NOTE That's NOT measuring the Neutral and Ground !!! 

Good to see some of my old brain cells recalled correct and it hasn't changed since I was an electrical designer years ago lol

Your posting additional information (above and beyond posters question) is a good and helpful thing in my opinion and I try to do the same myself.

Best wishes, safe travels, and God Bless you and all here

John T

[Lou Schneider]

A GFCI trips when the current flow through the hot lead does not match the current flowing back through the neutral lead, meaning part of the current is flowing back through a different path (maybe through the ground lead, maybe through you).

There are two ways this can happen ... the first is voltage leaking from the hot lead to ground or the ground lead. The GFCI trips as soon as you plug in the RV since the leakage is determined by voltage, not current flow.

The second is a high resistance leakage from the NEUTRAL to ground.  This won't show until you draw current through the circuit.  Drawing current raises the far end of the neutral above ground due to the voltage loss along the wire between the leakage point and the source.  

If you lose 10 volts along an extension cord, 5 volts is lost along the hot line and 5 volts is lost on the neutral return line.  Since the source end of the neutral is tied to ground, the far end will rise to 5 volts above ground forcing part of the current through any leakage point to ground.  This unbalances the hot and neutral lines running through the GFCI and it trips.

The amount of voltage loss along the wire depends on how much current you draw plus the wire's length.  Using a long extension cord will increase the neutral return loss under load, as will drawing more current.

This sounds like what is happening here since the GFCI only trips when you draw more current.  The trailer end of the neutral wire rises above ground and a leakage path from neutral to ground forces part of the return current through the ground conductor instead of returning through the neutral.

Since the problem appears to go away when you plug the heater directly into the extension cord, it suggests the fault is somewhere in the RV.

But leakage currents are additive.  You could be hitting the tripping threshold by a combination of smaller leaks that by themselves are not significant.

Do you have another heater you can try inside the RV, drawing the same amount of power (1500 watts)?  If it performs the same as the old heater (tripping the GFCI) it eliminates the heater as a contributor to the leakage current.  If the GFCI doesn't trip, the old heater is suspect. Wal-Mart has 1500 watt heaters for $10-15.  Try one in the RV and see if the problem remains.

[DuneElliot]

58 minutes ago, Lou Schneider said:

 

Since the problem appears to go away when you plug the heater directly into the extension cord, it suggests the fault is somewhere in the RV.

But leakage currents are additive.  You could be hitting the tripping threshold by a combination of smaller leaks that by themselves are not significant.

It does trip when plugged into just the extension cord, but only when I go from Low to High...this suggests to me that it is NOT the RV wiring.

[phillyg]

On 4/28/2017 at 4:34 PM, Mark and Dale Bruss said:

GFCI breaker can wear out

This.

[Ray,IN]

My understanding of the problem(after reading facts to date) is this; heater trips GFCI only on high setting, trips both GFCI's heater is plugged into whether in RV or into extension cord, a different heater causes the same problem.

Have you plugged the heater directly into the house GFCI yet, eliminating extension cord? Have you tried a different house circuit GFCI?

[oldjohnt]

 Right on Lou,   "A GFCI trips when the current flow through the hot lead does not match the current flowing back through the neutral lead, meaning part of the current is flowing back through a different path (maybe through the ground lead, maybe through you). "

That's how I recalled and described it and how the link Kirk posted described it. FYI it does this by passing BOTH conductors (Hot and Neutral but not ground) through a torroid coil so if the currents are the same no voltage is induced into the coil but if different there's a net current flow through a coil which induces a voltage. Pretty simple actually. Current out better equal current in or else its flowing elsewhere and its CURRENT flow that's being monitored.

 The OP is doing good and catching on and by plugging to different outlets with and without any cords or RV system whatsoever as described to see if the heater still trips regardless of the source will eventually lead to the cause of the problem which may be the heater itself.

Keep it simple, systematic substitution and elimination will solve the riddle regardless if the OP understands how a GFCI works but its still good to post additional info like all the fine gents and myself and Kirk did. WE all try our best to help our fellow RVer.

John T

[Kirk W]

From  SafeElectricity.org

Quote

What is nuisance tripping of a GFCI?

It takes only 5 mA (0.005 A) of current leakage from the hot wire to the ground to cause a GFCI to trip. A small amount of leakage current may be difficult to avoid in some normal circuits. Hand-held power tools do not cause a tripping problem if the tool is maintained in good condition. Some stationary motors, such as a bathroom vent fan or fluorescent lighting fixtures, may produce enough leakage to cause nuisance tripping. Another problem may be a long circuit with many splices. If possible, keep GFCI circuits less than 100 feet long. To avoid nuisance tripping, a GFCI should not supply:

• Circuits longer than 100 feet
• Fluorescent or other types of electric-discharge lighting fixtures
• Permanently installed electric motors

 

This could be what you are experiencing.