AC electrical question

[rdhoyum]

I have a 98 Excella 1000 with 30amp service and one AC unit.

Should the AC have a GFCI breaker in the main panel box?

I think PO may have made some changes in the main box.

[TouringDan]

I believe that the AC should be on a dedicated 20 amp regular circuit breaker. It should not be a gfci type.

Dan

[Minno]

No, the a/c should not be on a GFCI breaker. Probably won't hurt anything though. Might trip needlessly, which would be a nuisance.

Chris

[HowieE]

No The starting capacitor on the compressor motor will most likely cause the breaker to trip more times than you will be willing to but up with.

GFIs are only used where an individual can get between the receptacle and a good ground, ie a water pipe.

They are grossly over rated and misunderstood by a governing bodies that has no knowledge of electricity.

[TG Twinkie]

Here! Here! Howie!

[rdhoyum]

So consensus is regular breaker for the AC circuit. Which circuit should have the GFCI then? The main breaker??? or one of the other two. One of those is a 20 amp double pole...I'm guessing for the various wall outlets....then what would the other 30 amp be for?

I have the owners manual, but nothing technical for the trailer.

[richinny]

in my '94 34' the main breaker was 30A and the air/microwave was on a 20A. the gfi was for the bath/galley/fridge/outside outlet circuit.

[HowieE]

The above description is correct for your trailer. There is NO REASON what so ever for a double pole breaker to be in an Airstream trailer with a 30 amp service. Double pole beakers are used with 220 volt single phase systems which in a trailer system would not be required until a 50 amp service.

[rdhoyum]

Ok, I got the circuit breakers all sorted. AC on its own 20amp, the working GFCI for bath and galley, the double 20 amp breaker is circuits 3&4 for b-room, converter and liv-rm.

Here's the problem. The AC controls are connected to 120 line. The control switch, rotary knob, six pin connector is disconnected. Upon connecting it the shore line outlet(a GFCI) trips instantly.

I can only conclude it onto the roof to diagnose an AC problem.
I'm doing all this while at storage. I'll bring it home tommorrow to connect to 30 amp RV pedestal and confirm the AC works like it did before last trip.

Any suggestions on what to check/test in AC would be very much appreciated.

[rdhoyum]

One note!!!!!! The AC is off when connecting the controls. I made no attempt to turn it on......of course I have no power to do so.

[DKB_SATX]

So you're tripping a GFCI on the supply side of your shore-power receptacle, not one inside the Airstream?

Are you certain that shore-power receptacle just a mildly-annoying GFCI, or is it the REALLY frustrating arc-fault type that can trip when you're plugging in a perfectly safe appliance?

[HowieE]

If you are attempting to Plug Into a GFI as a source of power for the trailer and not talking of the GFI in the trailer you will never get power to the trailer unless you go in the trailer and turn off ALL the breakers.

What is happening there is as you plug into the GFI you are making contact with the receptacle in a sequence that is causing the GFI to see current across hot to ground before it sees hot to neutral. That will pop the breaker. The ground lug is longer than the hot and neutral and thus is the first to make contact.

Try turning off all the breakers inside the trailer and then plug into the GFI. Then you should be able to turn on the breakers inside. If at this point you still pop either the GFI inside the trailer or the one at the source you have a problem.

Report back if that is the case with details and we will go from there.

[Protagonist]

It's usually considered unwise to plug a GFCI-protected circuit into another GFCI. The first GFCI sees the next one downstream as a ground fault. One reason why campground 30-amp and 50-amp pedestals are not protected by their own GFCI; since virtually all RVs have at least one GFCI breaker inside the unit.

Remember, only one GFCI per circuit! So, if your trailer has GFCI breakers, do not plug your trailer into a GFCI-protected home circuit. If you have nowhere else to plug in, you should turn off the GFCI breakers inside your trailer and do without them for as long as your shore power is plugged into a GFCI outside the trailer.

Coventional wisdom also says that you should not plug in appliances that have a permanently-installed self-starting motor (air conditioner or refrigerator with thermostat-controls) into a GFCI. The starter circuit typically registers as a ground fault as soon as the motor kicks in.

[HowieE]

As long as we are talking the limitations of a GFI any system that has a filter cap across the input side of it's internal transformer will kick a GFI when plugged in. The charging current of the cap is enough to kick the GFI.

Lots of older audio/video equipment was so designed.

As a plant manager I had 15 steel work benches each with 12 AC receptacles mounted on them and test equipment that ranged as high a 80,000 volts. The local electrical inspector required that they each be on a GFI. They were till he left the building.

[rdhoyum]

Based on the discussion from HowieE and Protagonist I think, I mean I HOPE the problem is the power outlet at my storage place.

I though I had it solved with your mention of a faulty ground connection within the AC controls , realizing that the ground was only attached to the metal frame support bracket....hanging inside the AS....which itself was grounded to nothing.

So I buttoned it all back up, cleaned up the mess and tried it again. IT STILL TRIPPED THE GFCI.

I'm home and will hopefully get it working tommorrow at home. We need the little getaway planned so wish my well.

Based on the informative discussion we've had I think its just the "inherent" troubles outlined with a GFCI outlet.

I'll advised later in the day tommorrow. You've been a great help. Thnx!!!!!!

[Jammer]

rd

OK

We call these phantom GFCI trips. Well you can either take the advice of the posters upthread, to wit, that it's a philosophical problem rather than an electrical one, or you can chase the phantom trips.

Phantom trips are caused by one of two things:

1) A short between neutral and ground.

2) High leakage current on the hot side, often caused by moisture or a combination of moisture and dirt.

With an older Airstream the first thing to check is to be sure someone didn't short neutral and ground together on purpose, either in the breaker box, or in the shore power cord. There may be a bonding screw in the breaker box, if so, remove it.

Then you can see whether you still get phantom trips with all the breakers off. If you do, you have a short between neutral and ground somewhere, and to find it, you'll have to remove (with shore power disconnected) all the neutral wires from the bus and add them back in one at a time and see whether the GFCI trips after each addition.

If you don't get GFCI trips with the breakers off you can turn them on one at a time and see which circuit is the perpetrator, you're dealing with excess leakage at this point, and once you isolate the affected circuit, you can go around and clean and dry out the wiring devices with compressed air or a hair dryer or something, again being sure to disconnect shore power while doing the work. If that doesn't do the trick you might have excessive leakage in a component, maybe a heating element, or a MOV, or a circuit board. In those cases the problem part just has to be replaced.

A properly working air conditioner will not trip the GFCI. Usually if they trip it it's because of sloppy taping of the neutral part of the splice where power comes in. Less often, dirt and moisture on the motor terminals, capacitors, or controls. Rarely, a failing compressor may trip the GFCI.

Happy hunting

[rdhoyum]

Originally Posted by Jammer

rd

OK

We call these phantom GFCI trips. Well you can either take the advice of the posters upthread, to wit, that it's a philosophical problem rather than an electrical one, or you can chase the phantom trips.

Phantom trips are caused by one of two things:

1) A short between neutral and ground.

2) High leakage current on the hot side, often caused by moisture or a combination of moisture and dirt.

With an older Airstream the first thing to check is to be sure someone didn't short neutral and ground together on purpose, either in the breaker box, or in the shore power cord. There may be a bonding screw in the breaker box, if so, remove it.

Then you can see whether you still get phantom trips with all the breakers off. If you do, you have a short between neutral and ground somewhere, and to find it, you'll have to remove (with shore power disconnected) all the neutral wires from the bus and add them back in one at a time and see whether the GFCI trips after each addition.

If you don't get GFCI trips with the breakers off you can turn them on one at a time and see which circuit is the perpetrator, you're dealing with excess leakage at this point, and once you isolate the affected circuit, you can go around and clean and dry out the wiring devices with compressed air or a hair dryer or something, again being sure to disconnect shore power while doing the work. If that doesn't do the trick you might have excessive leakage in a component, maybe a heating element, or a MOV, or a circuit board. In those cases the problem part just has to be replaced.

A properly working air conditioner will not trip the GFCI. Usually if they trip it it's because of sloppy taping of the neutral part of the splice where power comes in. Less often, dirt and moisture on the motor terminals, capacitors, or controls. Rarely, a failing compressor may trip the GFCI.

Happy hunting

Thnx Jammer,

I have isolated it to the AC circuit. I still have to check for small issues that may occur in the breaker box, then its onto the roof to check out, clean, troubleshoot, and/or replace whats needed inside the AC unit.

[rdhoyum]

Plans to camp this weekend changed after a recurring back injury has me layed up for awhile. I have the "problem" isolated to the AC. may have been a bad breaker as I changed out the 30 for a spare 20 amp I found in the storage cabinet.

However, prior to that I removed the ground tab on the three prong adapter I was using with the 30 amp power cord to the 15 amp outlet at storage space. It allowed me to plug in without tripping GFCI. But still wouldn't allow the AC breaker inside to be turned on. Changed to backup 20 amp breaker "fixed" it all.

Hopefully I'll mend soon and can get it home for a short getaway and plug it in to the RV 30 amp power box at home and get the AC running without issue.

When I get onto roof to address skylight fixes, I'll check and clean all connections inside the AC unit.