Generator power

[ctwebb]

Hi all, We just got back from a week long trip and needed to use the generator for several days. I have a new Onan 5500lp. We where having trouble running both air conditioners at the same time. I switched all of the appliances over to lp to ease the power load and still could not run both, Do I have a problem with the gen set or is this common. I would think as expensive these gen sets are it would run both units

[H. John Kohl]

My first guess is that both AC are on the same leg of the two legs from the Generator. Therefore drawing to much current on one leg. It will take checking the circuit breakers or a meter to verify it.
Good luck and safe travels.

[Phil P]

X2 for H. John Kohl

That was the first thing I thought about when I read this.

Phil P

[K0LCB]

Is it wired for 110 volts or 220?

[Sniperduce]

From what I know about my own rv, our 5500 Marquis Gold LP unit will easily runs both AC units. Check to be sure both 25amp breakers are switched ON outside at the unit under the cover. I have to reset them once after the dealer serviced the transfer switch after it was recalled. Good luck.

[Rainer]

I would agree that it was incorrectly installed as to the wiring.

I have the 6500 Marquis Gold LP generator, yes it's bigger, but it works similarly. I would also recommend checking the breakers on the front left of the unit after removing the front cover.

And having said that, I had to take my unit back to a Cummins-Onan factory center to have an IC board replaced that failed after only 14 hours of use. So, it's not impossible that there's a defect.

But as my daddy always told me, if your hear hoofbeats, think of a horse first and a zebra a long time later.

I'd check 1) the breakers (both those on the generator and those inside your Montana, and then 2) the wiring.

[ctwebb]

Thanks guys it sounds like they are both on the same circuit. My gen set has a 30 amp breaker and a 20 amp breaker, The 20 will trip during this process.So to be clear the correct way is to wire them on separate breakers ? Looks like I will be taking this back to the dealer where it was purchased being this is the first time it was used .

[H. John Kohl]

quote:Originally posted by ctwebb

Thanks guys it sounds like they are both on the same circuit. My gen set has a 30 amp breaker and a 20 amp breaker, The 20 will trip during this process.So to be clear the correct way is to wire them on separate breakers ? Looks like I will be taking this back to the dealer where it was purchased being this is the first time it was used .

You say separate breakers when actually they need to be on separate legs. Your 50 amp plug has four prongs the rounded one is ground. The one opposite it is the common and the one on left and right are you supply legs (leg 1 and leg 2). In your fuse panel the breakers are fed by either leg one or two. I believe you will find that the breaker for each air conditioner are on the same leg. Your comment that you are blowing the 20 amp breaker at the generator (one of the Legs) seems to validate this assumption.
Too bad you aren't making the fall rally, there is a good electrician that could fix it in a jiffy.
Safe travels.

[mhs4771]

Our Onan 5500LP has two 30 amp breakers and easily handles both our 15K ACs without a problem. If fact we were using both this past weekend while dry camping in a parking lot attending a Cat Show.

[WaltBennett]

One 30 and one 20 is strange for sure. Sounds like the wiring isn't right.

[woodtic]

Could just be a bad breaker. Do both ac units run when plugged into shore power?

[ctwebb]

Yes both do run when connected to shore power

[ctwebb]

Thanks for your help john, Wish I was going to the rally , never been to one and sounds like a lot can be learned there.

[Phil P]

If they work on shore power and not the generator then the problem has to be in the wiring from the generator to the transfer switch.

Take it back to the dealer.

Phil P

[richfaa]

Both of my A/c's on my 2006 3400 were on the same leg wired from the factory. We had that changed to one on each leg. This 3402 was the same way. You would think they would know better.

[Phil P]

richfaa

Did you ever try your unit on 30 amp service before changing the AC to separate legs?

Phil P

[dmacy]

When you look at your electrical panel one a/c breaker should be on the left side the other on the right side. The right side is on one leg the left side is on the other leg.

[ctwebb]

Phil , I don't remember if we tried them both on the 30 amp service , And dmacy I looked in the breaker panel and both a/c are on the same side of the main, That looks to be the problem, Is it as easy as swapping a breaker to one on the other side? I am pretty handy but don't want to do anything to void my warranty, Think I will wait and see what the dealer does first...

[ctwebb]

Well, It looks like the dealer in unwilling to correct the generator connections so that both a/c units would run , They tell me the unit will not run both a/c at the same time.I find that hard to believe because there are several on here with the same set up as me and having no trouble.

[8.1al]

ctwebb,
go to this site http://www.cumminsonan.com/rv/select and print this page to show your dealer. Onan says your generator will run 2 ac units with "power to spare".