Why DO our AC units trip circuit breakers ??

[Gary.Jones]

Why DO our AC units trip circuit breakers (corrected)

I have not done this in the past, but have been doing this this summer: Running my AC units when the coach is sitting in the driveway and connected to 50 amp shore power. Because of mold and mildew worries in this very humid and hot environment, I have been running the AC units, and it has been common for one or two of the AC units to simply trip their circuit breakers leaving only one AC unit to cool the coach and work extra hard. So, the question is, why are the AC units tripping the circuit breakers? Other report this as routine when parked in very hot climates and it certainly is a common occurrence, but why does it occur?

The circuits (wires) are properly sized for the loads that they carry.... The 50 A service from the house is not the problem because that circuit breaker never trips, and the AC units should be capable of running fairly continuously if demanded by the temperature they are facing.

What are the thoughts on why this occurs? If I was living in the coach, I would be resetting circuit breakers on one or the other AC unit every couple of days. Doesn't make sense to me.

Gary

[royals1212]

Gary

How warm is the circuit breaker panels in the coach? My last outing, the sun was brutal on the front of the coach and my circuit breakers were getting warm. Opened the exterior panel and covers for ventilation. No problems.

Circuit breakers have about a10% plus or minus amp range of what is listed. Also they do wear out especially if they have tripped several times. Being multiple ac units,in my opinion, I would be looking the coach circuit breakers back to the power pole checking power and amps where you can. PMS module etc. Voltage disparities can cause the breaker to exceed its amp thru put. E (voltage) = I (current amps) X R (resistance)

[mel s]

Originally Posted by Gary.Jones

Why DO our AC units trip circuit breakers (corrected)
I have not done this in the past, but have been doing this this summer: Running my AC units when the coach is sitting in the driveway and connected to 50 amp shore power. Because of mold and mildew worries in this very humid and hot environment, I have been running the AC units, and it has been common for one or two of the AC units to simply trip their circuit breakers leaving only one AC unit to cool the coach and work extra hard. So, the question is, why are the AC units tripping the circuit breakers? Other report this as routine when parked in very hot climates and it certainly is a common occurrence, but why does it occur?
The circuits (wires) are properly sized for the loads that they carry.... The 50 A service from the house is not the problem because that circuit breaker never trips, and the AC units should be capable of running fairly continuously if demanded by the temperature they are facing.
What are the thoughts on why this occurs? If I was living in the coach, I would be resetting circuit breakers on one or the other AC unit every couple of days. Doesn't make sense to me.
Gary

Gary
What voltage are the A/C units seeing when they're running?
A/C units running on low AC voltage draw more amps than they do if/when they're running on 120VAC.

BTW if the A/C units are set so the compressors cycle off and on, (as opposed to cooling continuously), it is not uncommon for a "low voltage start up" to draw enough amps to trip the breaker.

Mel
'96 Safari

[twinboat]

As the rooftop coils get dirty, the amp draw increases.

I removed the cover, hoses out the coils with water and went from drawing 19 amps, down to 15 amps, when done.

[lowejug]

I know you said you had the proper size wire ran to your 50 amp outlet
But to me it sounds that might be your culprit , I have the same issue when I installed my 50 amp in my driveway the wire is undersized and blows the breaker under the big load of 3 AC s,, A electrician may be needed to ck this out
Does the same breaker blow when you are running just your generator ?
If they don't blow that at least tells u it's your shore power and not your something in your coach

[Kuppajoe]

Originally Posted by twinboat

As the rooftop coils get dirty, the amp draw increases.

I removed the cover, hoses out the coils with water and went from drawing 19 amps, down to 15 amps, when done.

Twinboat makes a good point. Check all three units for debris buildup. I have been suprised by the leaves that collect inside the housing. I use a leaf blower and hand vac to keep it cleaned out. Also, you should swap out those circuit breakers as they are being adversely effected by multiple trippings.

[MRUSA14]

Originally Posted by Gary.Jones

Other report this as routine when parked in very hot climates and it certainly is a common occurrence, but why does it occur?
Doesn't make sense to me.

Gary

It doesn't make sense to me either, and from where I sit it is not routine at all. It has never happened to me in three and a half years. Check your incoming voltage to see if it is low.

[Misty123]

I suspect the panel is getting to hot from the sun. Open the panels and see if that doesn't stop the tripping. It doesn't have to be too high amp draw, heat will also cause them to trip

[Gary.Jones]

I have a Progressive EMS-50 monitor on the circuit and everything checks out fine. No errors, no problems. Circuit is wired to 60 amps on both legs in the house. The house trunk breaker to the coach is not blowing..... never has. What is tripping are the individual AC unit circuit breakers in the coach. There is one for each AC unit, and they randomly trip on an aperiodic basis. One breaker will hold for a week and trip on the 8th day, whereas at another time, it may run for 1 day and trip on the second. No load voltage is 121 volts one one leg, and the other leg is 120 V. That is with 0 or 1 amp current draw. It is storming here now and I will go out and force them all on, and get the voltages and amperages. My memory would say that one leg is 18 amps (one AC unit running) and the voltage drops down to about 117 VAC and the other leg is about 36 amps and 115 VAC when all 3 units are running. My memory is that each AC unit is on its own 20 amp circuit.

Local heating of the breakers in their box has been my suspicion but I have never felt the breakers being warm, but then again, probably have not been feeling them at the time that the breakers trip. That is my bet. The coach faces south and of course, our sun is east or west which means that the front does not really take the majority of the heat, but now that I think of it, my breaker panel is above the driver seat and is on the east side of the coach.... Our heat has really been brutal for the past month..... near or above 100 every day. Maybe being on the east side, they are tripping in the morning sun..... ?

I will verify and document.

Gary

[Cruzer]

The breakers are thermally controlled. In other words they trip when they get hot. As voltage drops the amperage increases. When they amperage rises above the breaker's designed trip point (whether from low voltage or just too much load) they get hot and trip.

If the breaker is in a hot enclosure this affects the breaker because it trips at the same temperature but now it takes less amps to get to that temperature. I only had that happen once but I understood why.

It was due to heat in the compartment. Those two panels are in a fairly small area as far as the air behind the panels is concerned and if you are running enough power the panels do create heat. Combine that with the incoming heat from the sun and it can get warm in there. Entegra does use the correct wire gauge so that's not a problem. They do a good job of insulating in that area as well but insulation only slows the transfer of heat. It doesn't block it totally so eventually it will get in unless you can provide a fresh air intake to that area to exchange the air before it gets too hot.

I then installed an Airplate in my coach. This is a fan that is thermostatically controlled. It lets air into that area and has a nice LCD display with temperature and control settings. I detailed the installation it on my RVtechmag website but I'm not allowed to that site on this forum. It'
s basically a large computer style fan in an attractive grill that comes with a remote temperature sensor and an LCD control panel. I mounted the fan and the control panel in the face of the overhead cabinet to the right of the breaker panel cabinet. I bought the unit on Amazon (search for Airplate fan) and they also make a dual fan setup, which is fine for large entertainment center cabinets but too big and not needed for this application.

[MRUSA14]

Mark, the airplate mod on your website is awesome. I assume that the fan is running in exhaust mode. Where is the fresh air being drawn from, the space around the cabinet door?

[mel s]

Originally Posted by Cruzer

The breakers are thermally controlled. In other words they trip when they get hot. As voltage drops the amperage increases. When they amperage rises above the breaker's designed trip point (whether from low voltage or just too much load) they get hot and trip.

If the breaker is in a hot enclosure this affects the breaker because it trips at the same temperature but now it takes less amps to get to that temperature. I only had that happen once but I understood why.

It was due to heat in the compartment. Those two panels are in a fairly small area as far as the air behind the panels is concerned and if you are running enough power the panels do create heat. Combine that with the incoming heat from the sun and it can get warm in there. Entegra does use the correct wire gauge so that's not a problem. They do a good job of insulating in that area as well but insulation only slows the transfer of heat. It doesn't block it totally so eventually it will get in unless you can provide a fresh air intake to that area to exchange the air before it gets too hot.

I then installed an Airplate in my coach. This is a fan that is thermostatically controlled. It lets air into that area and has a nice LCD display with temperature and control settings. I detailed the installation it on my RVtechmag website but I'm not allowed to that site on this forum. It's basically a large computer style fan in an attractive grill that comes with a remote temperature sensor and an LCD control panel. I mounted the fan and the control panel in the face of the overhead cabinet to the right of the breaker panel cabinet. I bought the unit on Amazon (search for Airplate fan) and they also make a dual fan setup, which is fine for large entertainment center cabinets but too big and not needed for this application.

Cruzer
Nice!
https://www.amazon.com/AC-Infinity-A.../dp/B009CO543S

[Cruzer]

Originally Posted by MRUSA14

Mark, the airplate mod on your website is awesome. I assume that the fan is running in exhaust mode. Where is the fresh air being drawn from, the space around the cabinet door?

The fan draws air from the room and pushes it into the cavity, so it's a supply fan rather than an exhaust fan. I drilled a few holes in the bottom of the cavity, next to the roller shade, to allow the hot air to exit. So far I haven't seen the temperature rise to the point where it would kick in but it's been in the 80s here with not much sun - just high humidity and dew points. I expect it will kick in once we get to the Texas Hill Country net summer. I tested it in the various modes and even in the highest speed it isn't loud at all. There is a Smart mode that will start it off in low sped, then ramp the fan speed up if the temperature continues to climb. Well built and designed unit. I'm impressed.

[Gary.Jones]

Mark

Thats a great mod you did.... I like the look, fit, and finish and I may be compelled to make that change. I hate mNY motorcoach mods since many of them look like ham-handed mods, but this one looks like it is a factory install. Thanks for the link to your web site.

The price is certainly right and if it avoid the AC breakers from tripping then it certainly would be worth the price and effort. You da man....

Gary