How to deal with uneven load on 240 volt generator?

belfert · November 09, 2025, 03:29:15 PM

I plan to switch my air conditioning from 120 volt to 240 volt. Therefore, I need to either use an autotransformer for my A/C units, or switch my generator to 240 volt. I am most likely to switch my generator to 240 volt. How do I deal with most/all of my 120 volt load being on one leg of the 240 volt? My inverter is 120 volt only. I know the 240 volt generator heads don't like a highly unbalanced load.

A simple rough diagram of my plans is attached. I have more 120 volt loads than shown.

thomasinnv · November 10, 2025, 06:24:30 AM

Victron transformers can also be used to balance loads on a 240 ac source. Some other brands probably can as well.

belfert · November 10, 2025, 07:33:50 AM

One of my first thoughts was using a Victron Autotransformer directly after the generator to balance loads across the 240 volt legs. However, even though there is a 100 amp unit they have restrictions that probably make this not a great option, at least with the Victron unit. Outback Power has one, but limited to 25 amps.

thomasinnv · November 11, 2025, 07:11:24 AM

The victron is 28a continuous and 32a peak imbalance. There is a 32a or a 100a model. What are the limitations you speak of? Several people have them installed exactly for the purpose you speak of. If you have questions or concerns that are not covered in the manual you might try the victron forum for some answers.

David Anderson · November 11, 2025, 05:19:20 PM

Do you have two 120 volt hot legs coming off your genny output now?
If yes, you have 240v available.

Unless they are both on the same phase

David

luvrbus · November 12, 2025, 05:52:52 AM

I would call Jason at Wirco most of Dick's generators had 2 -110 volt leads, I called Gary for you, but he couldn't remember if yours did or not

belfert · November 12, 2025, 04:08:50 PM

I already talked to Justin at Wrico maybe a month ago. At the time I was more focused on using an autotransformer to take the 120 and change it to 240 for the A/C units than changing the generator to 240. It has been suggested to change the generator to 240 volt instead.

Justin was surprised I am using 120 volt as he shipped the generator as 240 volt. I followed the instructions in the manual to convert to straight 120 volt. One of the things I had to do was to tie the two legs together at the 50 amp breaker in the genset. Since I had no 240 volt loads I wanted to only do 120 volt. I am running two legs out of the generator from the two pole breaker, but they are each sized for 50 amps. The double pole breaker will trip if I use too much power on one leg, but I only had that happen once. I have spread the loads across the two legs as much as possible.

The limitation with the Victron Autotransformer is how much current you can have on the neutral. Even the 100 amp model has the same limit as the smaller one.

belfert · November 12, 2025, 04:10:25 PM

Quote from: David Anderson on November 11, 2025, 05:19:20 PM
Do you have two 120 volt hot legs coming off your genny output now?
If yes, you have 240v available.

Unless they are both on the same phase

I have two 120 volt legs on the same phase. I followed the instructions in the Wrico manual to convert to 120 volt. It would be easy to go back to 240 volt.

David Anderson · November 12, 2025, 07:08:41 PM

Switch back to 240 volt then. You will still have 120 volt on each leg (phase) in your panel. Nothing changes. You still get 50 amps on each leg.

Buy a 2 pole breaker and you have 240v to power your new air conditioning.

David

belfert · November 13, 2025, 08:04:58 AM

I could have the generator converted to 240 volt in less than 30 minutes. The conversion of the generator to 240 volt is not my concern. It is basically removing a jumper across the 50 amp double pole breaker, and moving a wire to a different spot on the terminal strip. I would not have to change anything else in my electrical system to switch to 240 volt.

My concern is in my current electrical setup essentially all of my 120 volt load would be on one leg of 240 volt. There could be up to 40 amps of 120 volt on one leg. 240 generator heads don't like a highly unbalanced load. I am trying to figure out how to deal with the unbalanced 120 volt load, or maybe it doesn't matter as much as I think it does. If I do a Google search there are plenty of web sites that state an unbalanced load can cause the generator head to overload. I attached a rough diagram of what my new setup would look like to my original post.

dtcerrato · November 13, 2025, 11:52:13 AM

We run our Onan with unbalanced loads. The built in circuit breakers will protect the generator head from overload. When unbalanced the unit vibrates a little more but has never been an issue beyond that.

belfert · November 13, 2025, 12:15:14 PM

Sure, the 50 amp breaker would trip if pulling too much from one leg, but it sounds like 40 amp on one leg and no load on the leg is not good for the head. (Absolutely possibly, but improbable, if the mini splits are not in use.)

bs4104 · November 13, 2025, 02:12:38 PM

What is the total KW of yours? Knowing that would make a difference in which way to go.
Bruce

luvrbus · November 13, 2025, 02:34:18 PM

The load balance deal is why so many of the higher end RV's use a inverter type generator, they don't care about balance loads

David Anderson · November 14, 2025, 05:06:11 PM

Arrange your loads on your breaker panel to balance between the two phases as close as you can.
I put ammeters on each phase of mine so I can see the loads while driving down the road. I'm usually within 10 amps from being equal.
I installed current transformers on each hot leg to show the amp flow on the ammeters. They are analog dial meters. They have worked for 20 years.
David