generation gap

[stlthe]

my generator is an onan quietdiesel 5500, circa 2004 (HDKBA series C). it provides a single-phase output of 5500 watts through 2 breakers, call them 30 and 20 if you will, but they are both labelled 30.

my bus is FE with a doghouse where my cupholder should be. I have no engine driven a/c. I understand some of the issues concerning amperage demand upon a/c compressor startup.

i have 1 each 11Kbtu, 13.5Kbtu and 15Kbtu airconditioners and was imagining that putting them all on the same 50Amp circuit together was the best way to make use of the power I have available from the gen and the fluctuations between the units for demand of energy (while the compressors are cycling). Right now this a mental exercise for me but i hope to find some real-world answers.

i have made the assumption that i could turn my 2-circuit output into 1 big circuit because they are on same phase, and that the one large circuit would do a better job than the two existing circuits of running the 3 a/c units simultaneously.

if we forego the 3 a/c good/bad discussion, is it safely possible to combine two circuits like this to creat a circuit with a sum of their (assumed) potential?
I would tie the white to white, black to black but i have only one green space on the block... i assume i would use 6 gauge for this.

if i had to use 2 circuits i'd put the two smaller ones together and put the 15 on its own.

to exclude this option lets posit 3 units at 13.5kbtu each with no other electrical capacity from nor demand upon the 5500 watts from genny. this will more clearly illustrate my dilemma.

thanks for life sustaining advice... do not spare my ego on any account.

[miltruckman]

Your generator is likely putting out 120vac on each circuit. You are correct that it is likely wired for single phase, but if you measure between the two 120vac breakers when the generator is in operation you will have 240vac. So you cannot combine them unless you want to let all the smoke out of the generator windings.

Bill

[Booyah45828]

It depends on how the generator is wired.

My generator head is a 2 coil unit, as are most 120/240 generators.

The coil leads are all connected to a switch. That switch's position determines if the coil's leads are connected in a series or parallel arrangement.

Here is a photo I found online that demonstrates it.


As you can see, with the switch flipped to 240vac mode, you get the graph on the left where the lead #'s 2+3 are connected to form a common neutral, with 1+4 having 240 VAC difference.

With the switch flipped to 120vac mode, you get the graph on the right where coil lead #'s 2+4 are connected and 1+2 are connected, giving you 120vac difference across the wire pairs.

Now, back to your question. You can wire it in a way to get one single 50 amp source, because the 2 coils are already connected together. But I don't think you'll be able to power 3 ac units off a 5500 watt generator. Typically, you'd run something that large off a 10kw unit because each ac unit requires around 3000 watts at startup. The minimum size they spec is 2800 startup watts per unit, and you'd still be well over 5500 watts with 3 units. So the most I'd run off yours is 2. And you can do that with the 2 circuit system you have.

[john61ct]

Easy Start units will help overcome the surge issue, but not solve your fundamental issue.

Personally if I ever wanted that much joice from a genset, I would buy one designed to output 240Vac, and likely a Euro version of the standard not the USA one, even if I was never traveling internationally.

Note there is a great device targeted at the EV travel charging crowd, where you want say 5kW Type 2 charging (240Vac) in a location with only 110Vac outlets available.

There are 2 long plugs, each gets plugged into a separate 15-20A 110V circuit.

If the device will work with a given pair, an indicator light goes green and the you can activate for fast charging (or any 240V USA type load)

If the light is red, you go try a different pair of circuits.

Can't find my link to this gadget, but thought it maybe relevant here.

[Booyah45828]

IMO, if you're running anything more then 20 amps on 120, you need to build a breaker box for your bus electrical needs. This way you can run each load or air conditioner off it's own breaker and not need to run 6 gauge wire to your air conditioners because you have a 50 amp protection device.

If you do build a breaker panel, you can then plug in your bus to shore power as well, or plug it into the generator when shore power isn't available. A simple 50 amp 240 vac rv socket connected to your generator would be all that you would need.

[john61ct]

Power Cor Adapter Inverter (Reverse Converter) Takes two 115 volt outlets and allows you to use 230 volt appliances that uses under 15 amp @ 230 volts (4600 watts) Single phase current to NEMA 14-30R receptacle

Fast and Easy 220 Volts

https://www.steam-brite.com/power-jo...r-p-12498.html

not a reco just FYI background info