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Author Topic: Generator Install Questions  (Read 622 times)

Sspreer02

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Generator Install Questions
« on: February 13, 2020, 09:21:23 PM »
Hello new here and looking for advice as Iíve searched the web for hours with minimal luck. I have a 09 kz inferno bumper pull Toyhauler and am looking at installing a Onan built in generator. The camper Says from the factory the 5500/50 amp is an upgrade and mine currently has a 30 amp shore cord so Iím figuring I have a 30 amp setup. I want to install the 5500 right out of the gate so I donít have any issues running at high altitude. My concern is the generators all seem to have two circuits a 30 amp and 20 amp. Is it pointless to do the 5500 with my 30 amp camper or is there a way to wire the Onan to provide 50 amps with one circuit?

Lou Schneider

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Re: Generator Install Questions
« Reply #1 on: February 13, 2020, 09:50:49 PM »
Welcome to The RV Forum!

There's no need to have the Onan deliver 50 amps, you'll still be limited to 30 amps by the 30 amp main breaker in the power panel.

On the plus side, at 3600 watts (30 amps) you'll have surplus engine horsepower that will limit derating as you go up in rlevation.
« Last Edit: February 13, 2020, 09:54:39 PM by Lou Schneider »

Roy M

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Re: Generator Install Questions
« Reply #2 on: February 13, 2020, 09:57:16 PM »
Welcome! 50A at 120VAC equals 6,000 watts which exceeds the capacity of your generator. 5500 is the maximum you have available for starting the a/c's, 80% of that is the realistic maximum for continuous running. To get 50A continuos you need a 7500W which is pretty big and heavy for rv use. Lou makes a good point.

Isaac-1

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Re: Generator Install Questions
« Reply #3 on: February 13, 2020, 11:30:36 PM »
This depends on what is important to you, the RV Onans are not particularly fuel economic, nor are they particularly quiet, though the 5,500 tends to be quieter than the 4000, or at least has a more pleasant tone.  If quiet and fuel economy are important to you look at one of the inverter generators made by Honda or Yamaha.
2002 Safari Trek 2830

John From Detroit

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Re: Generator Install Questions
« Reply #4 on: February 14, 2020, 06:08:30 AM »
The difference is in the automatic transfer switch.

Question do you have one or two Air Conditioners??  Typically if the generator is a 5500 designed for install in a 30 amp RV the breakers are 20 and 30 amp... The 20 amp runs one of the A/C's (usually the rear) and the 30 the rest of the RV.  The automatic transfer switch also has two circuits. One just for the rear A/C.    Look up the auto transfer switch manuals for more information on this.

If you plan to do teh "poor-mans manual transfer" ,methjod )(An outlet driven by the genny) Install two such outlets one TT30 and one standard 15/20 duplex GFCI. now plug the RV into the big one but rig one of the A/C's (your choice which) so the power line to it goes to an outlet next to the generator outlet. (also a 15/20 type) instead of to the A/C (you might have to cut, put in a junction box and extend) and a 12ga or heavier cord to a 20 amp plug so you can "Transfer" the 2nd A/C as well.
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Sspreer02

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Re: Generator Install Questions
« Reply #5 on: February 14, 2020, 07:30:58 AM »
We just have one AC just donít want to have issues running the ac, microwave coffee maker etc. The 5500 says output of 46 amps is where I got the 50 number from. So if I do the 5500 I just feed my panel off the one 30 amp breaker and the excess amps/watts would cover elevation output loss? Iíve been using a large 7200 watt worksite generator that spec 25 rates amps 50 peak, it did everything we needed but is loud and heavy. Would this Onan 5500 operate similar?

Gary RV_Wizard

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Re: Generator Install Questions
« Reply #6 on: February 14, 2020, 08:57:41 AM »
You could feed the main load center from the 30A output and run a secondary 20A feed to a new subpanel. That would give you some extra capability when using the genset, but only for the circuits powered from the new subpanel.  Owners sometimes do this to accommodate an extra 20A shore power line as well, so they can take more advantage of a 50A RV site.   It takes some wiring knowledge, but so does installing an onboard generator.

The real question is what are you trying to achieve? With a 30A RV, there isn't much point in exceeding around 4000 watts (33A @ 120v) unless you will make some wiring changes in the RV itself.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Sspreer02

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Re: Generator Install Questions
« Reply #7 on: February 14, 2020, 11:35:33 AM »
I am just afraid the Onan 4000 wouldnít have the output to run at 10k feet in elevation. Do you think it would?

Lou Schneider

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Re: Generator Install Questions
« Reply #8 on: February 14, 2020, 01:23:18 PM »
The 4.0 and 5.5 Kw generators share the same engine producing 5.5 kw of power at sea level, so their performance at altitude should be the same.  Onan says their engines will produce 67% of their rated horsepower at 10,000 ft, which means you'll have 3600 watts of driving power available.

Here's an Onan brochure explaining this:

Onan Technical Bulletin - Rating Factors for Electrical Generating Sets
« Last Edit: February 14, 2020, 01:26:26 PM by Lou Schneider »

John From Detroit

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Re: Generator Install Questions
« Reply #9 on: February 14, 2020, 05:42:18 PM »
I would still break out the A/C to the 20 amp breaker. NOTE that if you put in a 30 amp auto transfer switch it may well have the devices needed to do this automatically.   No need to run the A/C on the 30 amp breaker if you don't need to. it's the single biggest power sucker in the house
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Sspreer02

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Re: Generator Install Questions
« Reply #10 on: February 14, 2020, 06:01:15 PM »
Does anyone know a transfer switch model that would accommodate this? I like the idea of splitting off the ac

Gary RV_Wizard

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Re: Generator Install Questions
« Reply #11 on: February 14, 2020, 07:48:36 PM »
Any "50A" RV transfer will switch two separate power lines (plus the neutral).
Gary
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Gary Brinck
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Isaac-1

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Re: Generator Install Questions
« Reply #12 on: February 15, 2020, 12:00:31 AM »
What Lou said about sharing the same engine on the 4000 and 5,500 was true years ago, but is not true of the current models.  The current 4000 uses a single cylinder engine 3,600 rpms, and the 5,500 uses a 2 cylinder running at  lower rpms (2400), which steps up to drive the generator end at 3,600.

As to ability to run loads at altitude, I have a Onan 4000 on my coach, and have camped at as high as 8,800, at this altitude it will only run 1 major load (air conditioner, microwave, etc.), plus various minor loads.
2002 Safari Trek 2830

Deano2002

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Re: Generator Install Questions
« Reply #13 on: February 15, 2020, 07:05:22 PM »
Welcome! 50A at 120VAC equals 6,000 watts which exceeds the capacity of your generator. 5500 is the maximum you have available for starting the a/c's, 80% of that is the realistic maximum for continuous running. To get 50A continuos you need a 7500W which is pretty big and heavy for rv use. Lou makes a good point.
ours is a 6500 and we can run both 13, 500 ac's and micro/convection oven and electric water heater and lights, never blows a breaker
1989 Champion LaSalle 34' project