Please explain 2 ac’s on 30 amp service

[Fugitive861]

I recently looked at a 2005 Fleetwood Fiesta 31 foot class A. It had two factory, ducted ac’s and a 5500 watt Onan. Then I noticed that the shore power cord was a 30 amp and was plugged in to an outlet mounted in the cord bay (appearantly from the generator). I didn’t think a 30 amp service could power two ac’s even if they were both 13,500 btu’s. Certainly one ac isn’t hardwired to the genny while the other is tied to the shore power cord. If that was the case, only one ac would work on shore power only. Any insite would be appreciated.

[saddlesore]

Our former coach had 2 A/C's with a 30 system, Had no issues running both and once in a while using the microwave at the same time would trip the circuit breaker...but no biggie for us..It worked both on shore power and on the 5k genset for hours on end.
The cord from the gen set is because you may not have a hardwired transfer switch me thinks.

Happy Trails

[F4Gary]

In our 30 amp Southwind, when you set both a/c controls in the auto mode, it manages the amperage draw.

[CLIFFTALL]

My 01 Winn Chieftain was 30 amp and ran both. I had a power management system that would shed one if need be however it never had to as we managed to not overload it when both were running.

[Podivin]

My '96 Southwind was the same as others have mentioned, turn them both on and the power management system would 'shed' one or the other. Both fans would run, but only one compressor would run at a time. If the front compressor was running, when the temp in the front of the coach reached the set point on the thermostat the front compressor would kick off like normal, and then the power management system would allow the rear compressor to come on. When it got cool enough in the back then they'd switch again.

BUT, that's no guarantee that's how the one you're looking at will work. While that's what I'd expect, the only way to know for sure is to plug it in, turn on both ACs and see what happens.

[beamisl]

We have a 2005 Winnie with two A/C's. One is 11,00 BTU and the new one up front is 13,500 BTU.

We can run both units but are conscious if we need to run the microwave or a hair dryer we turn one unit off long enough to do so and then turn it back on.

When you turn something on go look at your AMP draw. This will tell you how much you can load without tripping anything. You will learn what you can do and not.

[twinboat]

Originally Posted by Fugitive861

I recently looked at a 2005 Fleetwood Fiesta 31 foot class A. It had two factory, ducted ac’s and a 5500 watt Onan. Then I noticed that the shore power cord was a 30 amp and was plugged in to an outlet mounted in the cord bay (appearantly from the generator). I didn’t think a 30 amp service could power two ac’s even if they were both 13,500 btu’s. Certainly one ac isn’t hardwired to the genny while the other is tied to the shore power cord. If that was the case, only one ac would work on shore power only. Any insite would be appreciated.

Some MH do wire a transfer controller that allows one AC to run off the second output of the 5500 watt generator.

30 amps is 3600 watts. That leaves 1900 watts, or a bit over 15 amps, to use.

When on generator power, you can probably run both ACs and the Microwave.

[rapid rick]

My 2013 terra has 2 ac's, 30 amp. I have a manual switch that moves power from microwave to ac#2. can run both ac's all day long just can't use microwave at the same time. It actually is a nice simple setup, we never use the microwave, well, except as a storage box. My wife used to use hair dryer at same time, no issues, since she passed, the hair dryer was discarded as my hair dries by itself within a minute or two without any power management, so all is good with 30 amp.

[jharrell]

Originally Posted by Fugitive861

I didn’t think a 30 amp service could power two ac’s even if they were both 13,500 btu’s.

My 15k BTU A/C draws around 15 amps, so conceivably I could run 2 on 30 amps and nothing else. Of course its really pushing it because if voltage low that increases amps and higher outside temperature causes the compressor to draw more, plus you have the startup surge.

I would imagine 2 13k btu's would be easier to deal with on 30 amps, but as others said there not enough left over to do anything else big like a microwave at the same time.

I have considered adding a second 13k "powersaver" a/c to the bedroom which is supposed to only draw around 10 amps: Coleman Mach - Mach 3 P.S. Power Saving RV AC | Airxcel

Also I would add a Micro-air easy start to it, just like my 15k btu to greatly reduce startup surge.

[Charlie 5320]

Originally Posted by Fugitive861

I recently looked at a 2005 Fleetwood Fiesta 31 foot class A. It had two factory, ducted ac’s and a 5500 watt Onan. Then I noticed that the shore power cord was a 30 amp and was plugged in to an outlet mounted in the cord bay (appearantly from the generator). I didn’t think a 30 amp service could power two ac’s even if they were both 13,500 btu’s. Certainly one ac isn’t hardwired to the genny while the other is tied to the shore power cord. If that was the case, only one ac would work on shore power only. Any insite would be appreciated.

If the coach doesn't have a power management system installed, the rear air could very well be wired directly to the generator. One way to tell is turn on both airs with the generator running and turn off the 20 amp breaker on the generator. Does the rear air still try and run or does it cut off when you turn the breaker off? My 95 Challenger was wired this way, but didn't have the second air, so the 20 amp breaker did nothing. I just left it in the off position, the coach had switches inside to run both airs on generator only.

[Tony Lee]

If you have a two or threeway fridge running on 120V , then that can draw 3 amps so switching it to propane removes a significant load off the mains. Similarly, turning off the battery charger frees up another couple of amps, so then you should be able to run both AC units

[wildtoad]

I once had an Airstream Landyacht MH with 30 amp service but a large generator. I forget the wattage but it was at least 5500. Anyhow, There was a switch much like a std light switch that I had to use to select which AC to use, living or bedroom. On shore power, one at a time. On gen I could run both.

[MisterT]

there are many 'wive's tales' in the RV industry, this being one of them. There is no 'electrical' rule that two of anything can't run at the same time on 30amps of power. Two ac units, which each draw at full capacity about 12 amps, can certainly run at the same time.
What everyone 'new' to the business does, though, is just 'believe' what they've heard, without trying it themselves to see if it's really 'true' or not.
Yes, there are times when you certainly need to run both AC units at the same time, and it's great that you have the ability to do so, even on 'only' 30amp shore power, BUT, yes, you can start tripping breakers if you try to add too much more to that scenario. This is exactly the reason for the industry moving to 50amp(100amp total) coaches in the more recent decades, and for especially the 'longer' and larger coaches.

With some coaches now having even three AC units, and electric cooktops, and residential fridges, you can see that 30amps would not work very well for them, at all.

Run all that you need, even when you 'only' have 30amp service. If you trip a breaker, then you know you're using too much... simple.

[seadaddler]

Yes sure you may run 2 ac’s on a 30 amp plug but if you try adding like a
microwave or water heater or some thing big draw besides tripping a breaker
you should check your plug and wire cord to see how hot it gets and may be
doing damage to the plug.
I did run one ac and microwave and did melt the plug and even melted inside the transfer box and did some checking to find out there was a recall on my 99
and did replace it and so check the electric cords when using big draw amps.
Nick