Community Forums

MN_Traveler · 06-18-2021, 07:45 AM

(EDIT- just noticed another thread about ac’s and park power that just got pulled up to the top of the list … not quite a duplicate as this one is really focused on the breaker issue … and so I will let this one stand…)

Main loads: 3 AC units (two on one circuit, one on the other circuit), oasis heating (two loads, one on each circuit), refrigerator). All has been working ok until recently. A few days ago, was at monument valley, and started to trip the main 50 amp breaker if running all three ACs. Worked ok if I only ran two, making sure I only ran one on each circuit.

I thought the problem was the low voltage at the campground 108v or so under load), BUT, yesterday ran from monument valley over to fredonia AZ with generator running. When running by Vermillion Cliffs national monument, I noticed I had no AC, and traced that to the main 50 amp breaker having tripped again. Got things running again with only two ACs running, and did not trip the breaker. So, whatever is going on was apparently not the power at the monument valley campground.

Am at a campground now just west of Fredonia AZ (Paiute nation RV park … big, neatly kept, International Dark Sky location [emoji4] … you gotta stay here!), and after bringing things up slowly adding loads one by one, here is what I have: under full loads (all three ACs running, oasis unit heating water, refrigerator running,television running, etc, one leg is pulling ~41 amps, the other about 35 amps. The individual AC units each appear to be pulling about 16 amps. The oasis heaters appear to be pulling about 10 amps each. So far I have not seen any unexpected transients (I do have a clothes washer and a dishwasher each with heaters, I’m not sure which legs they are on yet,but they were not running and so are not part of this mix). Just right now, everything is running, and the breaker is not tripping.

A couple points to add: the coach does have an energy management system integrated into it, and so neither leg should be allowed to exceed 50 amps. At monument valley it was hot (105 degrees). Running by Vermillion Cliffs it was HOT!!! (115 degrees). At the Paiute Nation campground we are at more altitude (100 degrees when we got in, 85 degrees now in the morning).

So … am I likely looking at a weak breaker, made worse when it is hot? Or … is even a healthy breaker susceptible to tripping when it is hot (if so, then what is the point of three ACs, since it is exactly when it is hot that you need them…. Or … should I keep looking for transient loads that spike and trip the thing? I have never in my life experienced a bad/weak breaker, so I am not really sure what symptoms show up. Experience from those who have would be appreciated!

Jyrocharlie · 06-18-2021, 09:52 AM

Be sure and check the connections on that breaker.

Old-Biscuit · 06-18-2021, 09:57 AM

AS Ambient temps rise....120VAC Load increases....amps increase/work harder

Weak breaker.....replace it
And check wire connections on ALL CBs, Neutral Bar & Ground Bar

MN_Traveler · 06-18-2021, 10:19 AM

Thanks for the confirmation on the breaker ..
And the suggestion to check the connections. Will do that tonight. Not sure how quickly I can get to a store to buy a breaker, but will try.

Thanks again.

Outbound · 06-18-2021, 10:56 AM

I agree, sounds like a weak breaker.

tropical36 · 06-18-2021, 03:36 PM

Quote:

Originally Posted by MN_Traveler

Thanks for the confirmation on the breaker ..
And the suggestion to check the connections. Will do that tonight. Not sure how quickly I can get to a store to buy a breaker, but will try.

Thanks again.

If you might have or find a clamp on ammeter (tong meter), you'll be able to tell pretty quick if the current draw is exceeding 50amps for any reason.

swduns · 06-18-2021, 03:54 PM

small molded case breakers have a short time magnetic trip and a overcurrent thermal trip

every breaker has trip curves that show exactly when they will trip based on the current

also the ambient temperature the breaker is in will affect its trip point

the LRC starting amps of your ACs also could trip the breaker on the magnetic trip ... the typical RV AC LRC starting amps is ~85A

if your loads were consistent I then you could see if its the overcurrent or short term trip causing it to trip but you have various other loads and they have duty cycles ... starting & stopping

it could be a weak breaker ... it happens ... but not ofter
it could be some other load that has some issue and is drawing too much current

you might try running the water heater on gas only so eliminate the electrical element load

if your swapping the breaker doesn't work you could experiment with all loads off except the 3 AC units then add loads and wait a period. The over current trip is an inverse time trip. if the load is 51 A it might take an hour to trip where as if it is 60A it would trip in a few minutes. so it might take some time for it to trip.

Nightshifter · 06-18-2021, 03:55 PM

When you pull the c/b out to check it look at the buss bar and the clips on the breaker for any signs of overheating like a discoloration in the aluminum. Most of the rv panels have aluminum buss assemblies in them and can corrode. If the connection was bad at the buss bar it may even be pitted. Carefully clean it with a scuff pad or emory cloth and coat it with an aluminum inhibitor like pennatrox before snapping in the new c/b. Hopefully it was just the screws that were loose.

Dutch Star Don · 06-18-2021, 04:52 PM

Just a note on your power use. In cold weather, we run both Oasis elements. In really cold weather, we turn on the burner for showers. In the weather you're experiencing, we get hot showers with just one element, saving some amps.

MN_Traveler · 06-19-2021, 07:50 PM

Quote:

Originally Posted by Dutch Star Don

Just a note on your power use. In cold weather, we run both Oasis elements. In really cold weather, we turn on the burner for showers. In the weather you're experiencing, we get hot showers with just one element, saving some amps.

Don - took your advice … doing this definitely helps reduce the load on the leg that has two ac units on it. Your comment also caused me to more seriously trace what loads are on which leg. Interesting … a lot of the high draw loads are on the same circuit as two of the ac units (like clothes dryer, dishwasher, ….) and some of those are not subject to the silver leaf load shedding (I’m still not sure how that works … the breaker box is just plain old breakers with wires running into them. Probably a junction box in the basement somewhere… more fun stuff to research [emoji4]).

Anyway, drove 120 miles RT today to get a new main breaker. Opened up the box, replaced the breaker, verified all wire connections were tight. Will see what happens. If it keeps blowing (which it did today when my wife fired up the clothes washer), I’ll need to look more broadly for cause.

(Two asides … 1) this gave me a chance to learn more about the systems in my new rig[emoji4]. 2) it is amazing how fast a rig heats up in the Arizona sun when it is 104 out, and the electric is fully shut down [emoji15])

tropical36 · 06-20-2021, 08:48 AM

Quote:

Originally Posted by MN_Traveler

Don - took your advice … doing this definitely helps reduce the load on the leg that has two ac units on it. Your comment also caused me to more seriously trace what loads are on which leg. Interesting … a lot of the high draw loads are on the same circuit as two of the ac units (like clothes dryer, dishwasher, ….) and some of those are not subject to the silver leaf load shedding (I’m still not sure how that works … the breaker box is just plain old breakers with wires running into them. Probably a junction box in the basement somewhere… more fun stuff to research [emoji4]).

Anyway, drove 120 miles RT today to get a new main breaker. Opened up the box, replaced the breaker, verified all wire connections were tight. Will see what happens. If it keeps blowing (which it did today when my wife fired up the clothes washer), I’ll need to look more broadly for cause.

(Two asides … 1) this gave me a chance to learn more about the systems in my new rig[emoji4]. 2) it is amazing how fast a rig heats up in the Arizona sun when it is 104 out, and the electric is fully shut down [emoji15])

Why not switch one of the ac's with a like breaker on the other leg?
They're must be a lot more than the two ac's that's loading up the one side, so maybe some arithmetic is in order for balancing out the whole panel.
Shedding should be adjustable as well. On our old coach it was all in the main breaker panel and do remember changing it around to shed the ac's only instead of losing the microwave, toaster, coffee pot....etc.

pogoil · 06-20-2021, 09:01 AM

My 2 cents,
I met a man a few years ago that worked for a breaker MFG. He told me breakers are not exact as to when they trip. He stated they have a range of 20 percent below rating or 20 percent above rating range. He stated to manufacture them to break exactly at rating we would not be able to afford them.
My knowledge before that was they tripped at 80 percent of rating. I have changed many weak breakers over the years.

MN_Traveler · 06-20-2021, 09:44 AM

Quote:

Originally Posted by tropical36

Why not switch one of the ac's with a like breaker on the other leg?

They're must be a lot more than the two ac's that's loading up the one side, so maybe some arithmetic is in order for balancing out the whole panel.

Shedding should be adjustable as well. On our old coach it was all in the main breaker panel and do remember changing it around to shed the ac's only instead of losing the microwave, toaster, coffee pot....etc.

Yeah, I thought about that … but it turns out that the entirety of the load going through the inverter is on leg 1. That includes the refrigerator, the microwave, and any other plugged in high draw load (toaster, hair dryer, etc). So maybe the potential imbalance of loads is not really that bad. Like you said, I need to do some observation and calls to see how the loads add up.

On my old coach (an expedition) the shedding was done in the panel also. But this “new” coach has a computerized silver leaf control system … and the electrical panel is just a plain old dumb breaker box. I have yet to understand how the silver leaf actually sheds a load … my guess is there is a box in the basement somewhere. Nordic know yet how to program it (there is a computer jack in the front panel … my guess is you need specialized cable and software…) There are a few glitches in the system I need to address when I have time and access to customer support … so I will probably try to address all of those when we return from this trip…

MN_Traveler · 06-20-2021, 09:54 AM

Quote:

Originally Posted by pogoil

My 2 cents,
I met a man a few years ago that worked for a breaker MFG. He told me breakers are not exact as to when they trip. He stated they have a range of 20 percent below rating or 20 percent above rating range. He stated to manufacture them to break exactly at rating we would not be able to afford them.
My knowledge before that was they tripped at 80 percent of rating. I have changed many weak breakers over the years.

Yeah - that is the way of electrical components. For example, resisters are manufactured with a pretty wide range of resistance values. Resisters that are sold as “precision” are not manufactured differently, rather they come out of a “measure and sort” process (which is expensive) , and are just selected from the output of the main manufacturing process. I would imagine breakers follow a similar manufacturing output.

That might well be what is happening here. Two ac units adds up to about 30 amps. One of the oasis heating elements adds about 10 amps. That’s about 40 amps. Dishwasher and clothes washer adds a few more … putting the load into the low-mid 40 amps. Add the heat to that, and a potential breaker that actually trips below 50 amps, and …. Well, that’s a problem. Dutch star Dons suggestion of taking one of the water heater elements off line helped a LOT to bring that load down.

Always something new to learn [emoji4]