Unable to run 15 amp shore power

[RidgecrestDad]

When we first picked up our 2007 3075 we stopped at a friends house on the way home. We parked in his yard and he allowed us to hook up to an extension cord plugged into a garage outlet (standard 15amp/30amp adapter in line). Things went fine, we even ran the air conditioner and a few lights with no problem. We stopped by his place another time and, again, we hooked up to his garage power. The third time we stopped, when we hooked up to his garage circuit the GFI in the wall outlet where the extension cord was plugged in IMMEDIATELY tripped. I mean immediately; we had nothing drawing power, nothing was on in the coach. We tried several other outlets and generally had the same result; as soon as we attached the power cable to the 5er the GFI tripped. I even had another adapter that we tried with no luck. Needless to say, it was a warm evening and we swealtered. Earlier on the same trip we plugged into a 30 amp service with no problems. (I am also able to hook up to 50 amps with no problem. Thought I'd throw that in for good measure.)

Upon arriving at home I tried the same connection as I have a 30 amp shore power hookup and a 15 amp GFI circuit nearby for general use. Same problem, the GFI IMMEDIATELY tripped. Hooked up to 30 amp and no problem, everything worked just fine. Then I plugged in an extension cord from inside that was not on a GFI circuit and I was able to run the air conditioner and a few lights with no problem.

The only thing that is different is we have an Onan 5.5KW installed. I went to the shop and spoke with the mechanic who installed the Onan and he maintains the circuits and transfer switches are separate and there must be something else wrong. Following the wiring diagram seems to corroborate his statement.

Anyone else have similar problems? Any ideas on how to track this problem down?

[Countryfolks]

You apparently have a short in the rig. Try turning all the AC circuit breakers in the rig off; plug in the power the same way as when it fails, turn on the main CB, then each sub CB on then off in turn. This may narrow the list of possible suspects.

[jimcol]

I would look at the 30 to 15 amp adapter. It could be the culprit as you are running OK on 30 amp service.

[Larry]

Another thought is that you may have stretched the operating limits of the GFCI outlet. Remember, these things are engineered to open at the least amount of current excess and as such, will not tolerate too many trips before they wear out. Life expectency, of any circuit breaker, is dependent on the amont of current draw and time in use. Rule of thumb, expect 80% efficiency and you probably will not be disappointed.

[kdeiss]

What was the AWG of the extention cord?

[Waynem]

I personally would run a thicker gauge wire such as AWG-12. Most extension cords are AWG-16 and that is not big enough to support what you are loading.

When I had the 3400RL I bought a 50Amp connector to 110v 15 Amp reducer. It was a pigtail about 12 inches long and screwed right into the 50Amp connector. The end of the extension cord plugged into the pig-tail. This gave me full voltage at 110V 15A throughout the Montana. I just had to make sure I did not turn on a lot of stuff or I'd blow the garage circuit breaker. I now have 50Amp service just outside the garage door.

[DHenry]

I do not know much about electricity but did your water heater switch get turned on, it maybe drawing to much for the GFI, just a thought.

[grampachet]

The H2O heater was what I was going to suggest too. Doug you beat me to it...

[RidgecrestDad]

Thanks to all who have provided ideas to fix this elusive problem.

I am fairly certain the electric water heater is not on. But since it is easy to check, I'll look at that first.

I also like the idea of killing all circuits and bringing them back on line one at a time. Think I'll try that second.

One thing I failed to mention is that I have ohmed out each adapter and the shore cable and see no anamolies (no shorts, no high resitance etc). Outside of verifying they are not shorted or corroded I am not sure what else I can try.

The extension cords were likely 14 guage at my friend's house. Believe mine is 16 guage. I agree, GFIs do wear out; could be both are tired although my power drill and vacuum do not trip my GFI at home.

If I bear fruit from the ideas I'll post the answer.

[HamRad]

Any time we use a regular extension cord to run shore power / generator we use a HD extension. The Heavy duty one is at least a 10 or 12 gauge. We've found that other wise the lighter stuff just will not get the job done on a reliable basis.

I searched for a week one time when I was literally getting a 'tingle' every time I touched the metal on the rig when hooked up with extension cord. I think I checked out every connection at least twice! Finally realized that someone (me most likely) had cut off the male plug and replaced with another. Well I had not reconnected the male plug correctly thus was getting a ground fault constantly! Once I corrected that all was once again well!

And I had really given the dealership the "what for" for not being able to replicate and fix my problem. Needless to say there was a bit of 'eating crow' involved for a few visits.

Good luck and let us know what you finally resolve.

HamRad

[dieselguy]

I have no other suggestions other than previously stated about your GFI situation .... however I would like to throw in a little food for thought on running your AC along with lights and what have you off a 15 amp plug in in someones garage. More than likely the converter and fridge, along with "phantom electricity" from the surround sound, microwave, and TV's are tapping current right along with the AC. You are shortening the life of your AC each time the compressor cycles as I doubt if you have anywhere near 115 - 120 volts at the unit. I know we've all done it one time or another, but I sure wouldn't make a repeating habit of it as they sure don't give AC's away or the service that comes due with it. JIMHO!

[2 for Him]

Barry,
The older converters had a thermister in them that ramped up the voltage to the capacitors in them to keep from having a super large draw when plugging in, the new ones don't for cost reasons. Our replacement Iota converter blows the inside breaker about half the time, resetting it immediately fixes it. Got a slow blow breaker from my "stash", works great now.
You should find if it is this by trying the breakers one at a time.

[RidgecrestDad]

HamRad, I thought for sure I was the only person on earth that would improperly make a simple change hard and embarrass myself. Thanks for sharing. I promise to keep it a secret between you and I only. Well you and I and the other 217 readers so far.

Dieselguy, We normally do not do garage power. This buddy just happened to get the pleasure of our company once too often.

And for Tom and Georgia, I may not have been clear. The GFI that trips is the one in the garage, not the 5er.

Thanks again to all offering ideas. Nice to have the help.

[RidgecrestDad]

For those who offered suggestions. I found the water heater circuit breaker was off, therefore do not believe that is a causal factor. I also shut off all circuit breakers and brought them on line one at a time. No individual breaker tripped the shore power GFI; however I was unable to run the central vacuum or air conditioner when I could keep the power on the rig. Still at a loss.

[NCFischers]

Barry,
Is the GFI in an outlet or circuit breaker? If the GFI is in the outlet and is tripping, then you have a fault to ground, not an overload which would cause a circuit breaker to trip. They perform two different functions. You said that you plugged into a non GFI circuit and it worked. I would look for a fault to ground on a non GFI protected circuit in your rig. As a note, compressors like AC compressors can cause a momentary fault to ground. This is normal in compressors and usually not a problem. Another thought, what kind of condition is the extension cord in? As previously stated, I wouldn't use a cord that was less that 12 gauge. The length of the cord can also be a factor.
Good luck, I wish I could help you more.
Jim

[RidgecrestDad]

Jim,

The GFI in the outlet is the one that trips. Consequently your suggestion to look for a fault to ground in a non GFI protected circuit is a good one. Not sure how I'll find one as bringing each C/B in the rig on line one at a time did not trip the GFI in the outlet. Thoughts?

[NCFischers]

Barry,
As I stated, the AC could be tripping it and you may not have a problem. Just turning on the CB's may not duplicate the problem. Try turning on things one at a time in the rig and see what happens.
Jim

[scattershot]

Didn't read all the posts, but could you have had your water heater set on electric power? That will draw a lot of electricity, possibly enough more that it would trip the breaker.

[jjfavret]

May not be the same problem, but in the past couple of years, when I hook into a 20 amp GFI I blow the breaker where I plugged in. Did some checking and found if I unplugged the micro wave I had no problem. Ran an extension cord to the micro wave and no problem. Put a tester on the built in micro wave box and it appears I have a ground & neutral touching in the line. There is no problem when we are not at a campground without GFI. I have checked the plug and wires as far as I can see. Must be a screw has poked the wire and shorted the ground and neutral, not a problem unless on GFI.

[RidgecrestDad]

jjfavret,

Hmmmm..... Sounds interesting. Perhaps I have a similar problem.

Thanks for the tip.