Altitude Degradation

[xvrfczm4]

Twice this year I have been in "high altitude" campgrounds, that is, over 2000 meters (approximately 6565 feet) and coincidentally, both Thousand Trails (Idyllwild and Snowflower - hmmm, both in California - a clue there?) in my 2005 Tiffin Phaeton 40QDH. In both cases, I lost AC power to part of the systems but not all and, in both cases, the same circuits. Looking through the coach and the electrical diagrams, I and a service tech at Bob's RV in Hemet, CA, can only locate one GFCI outlet and the assumption is that both AC circuits from the inverter go through it.

In the first case, testing and resetting the GFCI accomplished nothing. Green light on but no power to the satellite, TV's, most outlets, the refridgerator. Some outlets, the microwave, stayed on. Bob's replaced to GFCI outlet and everything was OK. In the second case, the GFCI went out and the rest did not work (instant trip) but same circuits worked or not as the first.

After the second failure I drove down to Sacramento looking for a Tiffin dealer and some help. While waiting I checked into a campground (the California State Fairgrounds has an excellent facility). While pondering the mysteries of electricity (NOT my strongest suit) I reset the GFCI outlet once again (I am a glutton for punishment or insane doing the same thing over and over but expecting a different result) and everything worked! And has continued to work with no problems, though I have not been above about 4500 feet since (but heading for Glacier NP in Montana). I am now thinking the replacement in Hemet was really not necessary but just coincidentally solved the problem because it was substantially below 2000 meters at that point.

After regaling my favorite (only) son with all this he sends back information he found on the internet laying the problem on the doorstep of something called "altitude degradation". The issue is apparently the higher one goes devices like GFCI outlets and most circuit breakers cannot dissipate heat rapidly enough and the unit overheats (like it would in a short) and trips the circuit. Conveniently, GFCI outlets and most circuit breakers are apparently only certified to 2000 meters.

Talking to folks about this, including some service managers, I cannot find anyone who has ever heard of this. Anyone out there ever heard of it?

Secondarily, does anyone know of a 15 amp GFCI outlet certified to more than 2000 meters?

And finally, if this is a factual problem, shouldn't RV manufacturers use CFGI outlets certified for higher altitudes (or at least warn buyers of the potential problem?).

I think I have a handle on the problem and, if it should recur, I won't get upset about it but it would be nice if it could be fixed!

[Lenp]

Circuit breakers do degrade with elevation and I would assume GFI would also.  However the degradation is nominal (maybe 15% at 10,000 feet).  The device is still doing it's job.  I suspect you do indeed have some leakage in that circuit but just under the threshold required to trip it at lower elevations and just high enough at elevation.  I would be looking for an appliance or something else that is causing the problem at elevation.  Start by disconnecting everything on that circuit (the next time it occurs) and then add them all back one at a time.   My bet is one of them is leaking some current to ground.

See http://bdbreakers.com/deratealtitude.php for details on circuit breaker degradation.

Lenp

[dickandlois]

xrvfczm4, Welcome to the FMCA Forum ! 

You mentioned that trouble shooting is not one of your shill sets, How about working with 120 volt / 50 amp power circuits? 

The most common item that causes GIF to trip is a abnormal resistance between the Neutral and Ground buses in the AC power panels, Connections at the ATS, in the 4 in. square "J"  connecting the generator output to the wiring going to the ATS and Loose connections caused by the Connections at the ends of the shore power cables.

They tend to loosen as we drive the coaches down the road or the plugs ans sockets from use.  Many coach owners have a yearly check list that includes tightening all the neutral and ground terminals located around the coach.

 If you are not sure of working to tightening them - have a service tech go through all of them. No power to the coach from the generator, shore riser or inverter(inverter turned off).

Rich. 

[manholt]

I have had no problem with the GFI's in my coach, I have 4, at any elevation below 10,000 feet. Have never camped above 9,200!  Linda has a 40 foot, 2006 Phaeton and it has one GFI, located in bathroom, for whole coach!  Hers goes off at any elevation!  So, we will do your suggestion Rich and see what happens! I'll get back to you on that.  

X, do you use a portable Surge Protector, like Progressive, at the campground post?  If not, you should.  Do you lose any 120v power when your on generator?  

[dickandlois]

Carl, the charts I have posted regarding the power loose at altitude are excellent as a relative reference. When one wants to know the drop in HP at elevation = A little lower output in KW,  but the voltage is steady at 120 volts in most cases.

Condition of the filters and carburetor  or inches of LP settings being off can cause surging - that issue will change frequency and frequency has a direct affect on voltage when the generator speed drops. Be it 1,800 for a 4 pole or below 3,600 for a 2 pole system.

Diesel generators are not affected to the same, but they do loose  KW per 1000 ft. changes. When running they Tend to be more frequency stable , but one has to remember that diesel powered units have more HP to start with. 

Clear as modded water  . Your background and sight work most likely exposed you to some interesting challenges. 

The coach is protected with a surge protector, but when there is a storm in the area , I just disconnect from the riser and run the inverter if necessary.  Very seldom been where we needed to run the generator. Major grid damage an it has run for a few hrs .

Rich. 

Carl, was it your model year that had the recall on the power panel circuit breakers ?   

[manholt]

Rich, dielectric change at high altitude, will also affect the voltage.  Not to any bothersome degree, below 11,500 feet.  Above that, it decreases voltage exponentially.  At 13,000 feet, it drops to .85% of 1v per = 102v depending upon the insulation properties, of the material used. 

It will not affect the GFIC, as it will still trip, at the same amperage. 

Recall CB?  Not that I'm aware off...but will check!

[alflorida]

9 hours ago, xvrfczm4 said:

The issue is apparently the higher one goes devices like GFCI outlets and most circuit breakers cannot dissipate heat rapidly enough and the unit overheats (like it would in a short) and trips the circuit. Conveniently, GFCI outlets and most circuit breakers are apparently only certified to 2000 meters.

OK, so a c/b degrades some when going up in elevation.  To me that means if the c/b is rated at 15amps a sea level, then at 10,000 feet it is now rated at 14 or even 13 amps.  Even at 13 amps, unless you are plugging in a toaster or a 1500 watt electric space heater the circuit should work just fine. 

I think you can disregard all this altitude stuff as the problem unless you are tripping the c/b with a space heater.  

You need to be trouble shooting the problem with a volt meter to find out where the voltage is missing.  If the c/b is tripping then you have an overload. 

If the GFCI is tripping (that is a different problem than a c/b tripping) then that is more difficult to identify.  But again the GFCI tripping is not an altitude problem.  The GFCI tripping means the total current going back on the neutral return wire is less than what came in on the hot wire.

[kaypsmith]

1 hour ago, alflorida said:

OK, so a c/b degrades some when going up in elevation.  To me that means if the c/b is rated at 15amps a sea level, then at 10,000 feet it is now rated at 14 or even 13 amps.  Even at 13 amps, unless you are plugging in a toaster or a 1500 watt electric space heater the circuit should work just fine. 

I think you can disregard all this altitude stuff as the problem unless you are tripping the c/b with a space heater.  

You need to be trouble shooting the problem with a volt meter to find out where the voltage is missing.  If the c/b is tripping then you have an overload. 

If the GFCI is tripping (that is a different problem than a c/b tripping) then that is more difficult to identify.  But again the GFCI tripping is not an altitude problem.  The GFCI tripping means the total current going back on the neutral return wire is less than what came in on the hot wire.

I agree totally with this statement. First, let me say that an AC should have never been associated with a GFI circuit for any reason. If the coach manufacturer installed it on one, it was done so in error. Even the electrical building codes allows for a refrigeration unit to be placed on a basement floor without GFI, no other device, an AC is a refrigeration device. Refrigeration compressors do create an electrical problem with GFI due to its delay equalizing the amperage between the hot side and neutral, this difference is the only thing that GFI looks for in determining when to trip, it doesn't care about over current, only milliamp difference in draw between hot and neutral. Normal difference allowed is only 4 milliamps, anything different is any degradation due to age of the GFI breaker, or a bad GFI from its beginning, and this does sometimes occur. I probably should add, overtripping of the GFI as a reason for shortened lifespan.

[dickandlois]

Circuit breaks react to current draw and GFI's  react to current differences between the hot feed and the common return.  Poor or loose connections in the breaker boxes can cause false tripping of the GFI.  The other item that we have run into - is power strip's with inexpensive surge protectors can trip the GFI when turned on and off.  

The ground wire is bonded to the common at the breaker box and the ground wire is connected to the outlet - that connects the metal case of appliances and tools to protect against shock hazards should the high side shout to a metal case. 

Note, There have been some recalls of coaches, because the circuit breakers used where defective. So do yourself a favor and check for recalls regardless of what the make, model and year coach you own. Kind of like checking with the Tire shop or RV dealership that they did registered them, so you get a notice of a defect. The devil in in the details and way to often they slip through the cracks.

GFI  circuit interrupters are designed to handle 15 or 20 amps.(if one looks at brand catalogs) Should one place a 20 amp GFI in a 15 amp circuit. It will respond with the same difference in current that is set near 5 ma. They just do not care what the circuit breaker size is.The wire size - GFI's can be wired with is 10 gauge   down to 14 gauge wire. The fact that a 20 amp GFI  will do the same job as a GFI rated at 15 amps. If you ask and look at the box the GFI's come in - the information will most often indicate a 20 amp rating.  That makes them fit, residential  applications for lighting circuits-15 amp lighting circuits and 20 amp duplex electrical outlets.

Rich.

 

[kaypsmith]

Just for understanding purposes, 1 milliamp = 1/1000 (one thousandth) of an amp. At 120 volts  that's 5/1000 amps or, 0.60 watts using the guidelines for a GFCI breaker. Not much current, many start capacitors used on refrigeration units will cause a disruption of more than that, this is why refrigeration units do not do well on GFCI.

[manholt]

Or AC's.  Where there is flowing and/or standing water !  Like a shower, tub or sink=GFIC !  Yes, UL is .5ma.  I would like to see .3 or .4ma!

[wayne77590]

...and GFI receptacles are polarity specific and are usually marked + and -, hot and neutral. If the wires are crossed it will never reset.

[kaypsmith]

45 minutes ago, manholt said:

Yes, UL is .5ma.  I would like to see .3 or .4ma!

Carl, that's 5 ma not .5, most manufacturers use 4 ma just to beat the electrical quidelines, and self preservation.

 

29 minutes ago, wayne77590 said:

If the wires are crossed it will never reset.

Correct!

[desertdeals69]

I was at Snowflower TT last week and ran both ACs on 30 amp service just fine.

[manholt]

Kay.  Have no clue, why I used .5