RV tripps GFI outlet?

[427v8]

Hi Everyone.
I decided to put a GFI 30 amp outlet on the outside of my house in a weather proof box so I can plug in my little C without using a 100' extension cord.

It works great except it blows the house GFI!
If I disable the house GFI all is good, grrr.
The Motorhome does have it's own GFI protection inside, do you think plugging a GFI protected RV into the house GFI outlet could trip the house GFI outlet???

Or do I realy have a GFI issue. Everything is off but the microwave clock...

My main concern is that I'll get to a campground, it will have GFI power and I won't be able to plug in!


Keith

 

[Ned]

It's not unusual for RVs to be wired such that they will trip a GFI outlet.? The most common problem is the ground and neutral being tied together somewhere in the RV, often in the inverter.? To test that, temporarily lift the ground wire from your shore power input (most easily done at the transfer switch if you have one) and see if that solves the problem.? If so, then that's most likely the cause.? You then either have to track down the point where the ground and neutral are tied together or forgo the ground wire and the GFI protection.? I do NOT recommend the latter.

It's also possible that you have a true ground fault elsewhere and that will take a bit more work to locate.? It will require knowledge of AC power systems and how they're connected, so if you're not comfortable with that, you'll need an electrician to help you.

 

[427v8]

Thanks Ned,
I guess it's time to dig into the electrical system, AC doesn't bother me much. But I don't like not having a GFI on an outside outlet...

Just 1 more thing to fix ;-)

 

[Ned]

But I don't like not having a GFI on an outside outlet...

I believe the electrical codes require that.

 

[427v8]

This guy talks about GFI trips specifically in RV's and even mentions the NEC exempts 30 amp RV outlets...I gotta go find that reference.

http://personal.cha.bellsouth.net/j/o/johngd/files/rv/gfi.pdf

 

[Ned]

Thanks for that reference.  There are some interesting comments about RV applications, particularly the RFI filtering on converters (and probably inverter/chargers as well). 

 

[Pat]

v8:  Very informative article. 

I ran into a problem this week.  I bought a TrippLite surge protector for my computer.  It also has coax protection, phone, and Ethernet.  And it has a bank of widespread plugs for large adapters. 

My GCFI tripped the other day.  At the time I didn't realize the GCFI had tripped, but I did have to reset it to get the outlets going.

Today it tripped three times, each of them getting closer.  I removed the surge protector and plugged the computer into the same ceiling outlet that the surge protector was in.  Needless to say, the rest of the stuff isn't plugged in anywhere, but it's not needed all the time.  So far no more trips. 

I emailed TrippLite asking about the problem.  Sure hope that solved it.  I had a surge protector on my computer before, with no problems.  Mailed it off to my nephew along with the spare strip that came with this one, so now I guess I'll have to go buy another cheapo.   

Anybody know anything about the characteristics of surge protectors that would cause this?


--pat

 

[Lou Schneider]

Surge protectors work by shunting surge voltages to ground.  GFIs trip by detecting current flow from the main circuit to ground.  Any time the surge protector works, even if it's only for a minute amount of current, it will trip a properly functioning GFI.

Depending on the component tolerances between the surge protector and GFI, it's even possible to trip a GFI by simply plugging in a surge protector into a GFI protected outlet.  Even if there's no surge voltage present.

 

[Pat]

Lou:  So the previous surge protectors that I've been using in here the past 4 years were not working properly?  I think this is my first TrippLite in here.  It had hookups for coax in and out, and I wondered if the proximity of the coax cable to the power cables on the surge protector was causing problems.  This one didn't trip the GFI all the time, but it was getting more frequent. 

Does that mean the surge protector was protecting against surges when it tripped the GFI?  Maybe I shouldn't be running this computer on the outlet, until I get another surge protector to try tomorrow. 

I HOPE that the computer wasn't generating the surges.

I thought maybe the heavy cord and flat plug of the surge protector were pulling it out of the ceiling outlet into which it was plugged, causing some kind of problem for the GFI.  All my outlets are under cabinets facing downward, so all plugs, bulky, heavy adapters, and anything else I need to plug in, have to hang from the ceiling.  For the heavy stuff I run an extension cord down to a piece of furniture to get the weight off the outlet.

--pat

 

[Lou Schneider]

I'd try a different brand of surge protector before going further.  It may be the component tolerances in the Tripplite allow just enough leakage current to ground under normal operation to trip the GFI.  A different brand may not shunt as much current to ground.

We're not talking about gobs of current.  5 milliamps or 0.05 amps shunted to ground is enough to trip a properly functioning GFI.

 

[Karl]

Lou is right - with a small exception.
A GFCI does not need a 'ground' to work; it senses a difference between the current draw between the 'hot' and 'neutral' sides of the appliance which is plugged into it.

While GFCI outlets are quite relaible, they do age over time and can become less tolerant, just like a normal circuit breaker. If you're experiencing increasingly frequent faults, you may want to consider replacing the GFCI also; not just the surge protector. 

 

[Pat]

The surge protector was plugged into an outlet down the line from the GCFI.  Does that make a difference?

The only GCFI outlet in here is low on the wall by the back door.  It's the one I reset to fix the problem.  I'm in rain country, so there could be moisture, but I'd put my money on the surge protector as the culprit, especially since the outlet hasn't tripped since I removed the protector.  The protector is a TrippLite, which I have always heard to be very good.  Great little thing with the coax, widely spaced plugs with sliding dust covers, phone and ethernet protectors.  Anybody want it to test?

Tomorrow I'll go to Ace to find something generic.

--pat

 

[Karl]

Pat,

The surge protector was plugged into an outlet down the line from the GCFI.  Does that make a difference?

No. A single GFCI will protect all outlets wired downstream from it; you don't need individual GFCI outlets at each point.

Try plugging a single 120 volt lamp into the surge protector and turn it on. If it doesn't trip the GFCI after a reasonable period of time, my bet would be one of the devices you had plugged into it was the cause of the problem - not the protector. 

 

[Pat]

Karl:  Good idea, which I will do.  Today I bought a small, 3-outlet surge protector that is attached right to the plug in the ceiling, with the computer plugged into it.  No phone line.  No ethernet.  The coax is unprotected.

I'll do the lamp thing.  However, if the problem is that the plug takes a while to work its way out of the outlet, the lamp could be on for days before the problem occurs.  It tripped one afternoon, and then around the same time about 3 days later, and then an hour later and then a few minutes later.  Shorter and shorter waits.  I didn't like the mess of wires I had attached to it anyway.  I can plug things in as I need them.

--pat

 

[Pat]

As a follow-up, Tripp-Lite finally replied to an online inquiry that that surge protector was "not designed to work with a GCFI receptacle."  Something to look for when purchasing these things, I guess.  I saw nothing obvious to that effect when I bought it.  Don't have the packaging or the instructions.  There was nothing printed on the surge protector itself.

--pat

 

[Ron]

Gee if they had mentioned on the package it had such limitatiojns as not working with a GCFI they would have lost a sale. ;D

 

[Gary RV_Wizard]

Most common surge protectors work by dumping excess current to ground through a device called an MOV. When it does so it would indeed trip a GFCI. But it should not be dumping current to ground all the time, unless you have a steady "surge" in the line.  That's possible in an RV, because there are things in an RV that often generate surges and noise in the power lines - the 12V converter being one such thing.

There are expensive ($200+) types of surge protectors that would not do this, but probably aren't worth the cost for your needs.  You might consider putting a "whole house" surge protector on the RV's load center o rits power cord and protecting the whole RV. For a power cord surge guard and also high/low voltage protecor, see Surge Guard

 

[Pat]

Gary:  I did invest in a whole house surge protector once.  I'm hoping they've been improved.

Couple things I noticed about the surge protector that I bought for the house.  It was too long for some campground posts, plus it was stiff and inflexible.  Second was that, because of its length, the connection with the 30amp plug was always out in the elements.  And close to the ground.  After something happened, and I don't remember what, because it's been years, that seemed related to the surge protector, I just took it off permanently.  I think I wasn't getting power through it.  Carried it around for a year or two before throwing it away.  One small action I take is to unplug at the post if the campground has a power outage (planned or unplanned).  No surges at startup.  I run an extension cord out to the 110 plug at the post and turn on a fan or some noisy machine, and when that starts, I know power is back up.

Regarding the surge protector for the computer, I got a small 3-plug one at Ace that has as high joules protection as the strips.  This one plugs directly into the ceiling outlet.  No cord.  The computer plugs up into it.  It's a bit of a bandage, because when I print, I use an unprotected outlet, but there's not a lot of chance of a problem in the minute or two that I'm printing.    I use a USB connected cellphone for dialup usually, so no phone line protection there.  I do have the TV coax cable attached to the computer and should protect that.  This little 3-outlet plug has not tripped the GCFI in the week or so it's been installed.  Looks neater, too.

I will let the guy at Radio Shack, where I bought it, know that TrippLite says they don't work with GCFI protected outlets. 

--pat