30 AMP and 2 AC Units?

[Rawn77]

I've ordered a new 31' Classic which will come with 2 AC's (15k and 13.5k) and 50 AMP service.

Have any of you guys used a 50 to 30 AMP pigtail and were still able to run both AC units (assuming no other significant electrical being used {hot water and fridge running on propane})

For those quick one night stops, it would be nice to not have to wrestle with the 50 AMP cordset; the 30 AMP cordset is way easier to deal with.

Just wondering

Ron

[SteveH]

Know just what you're talking about. That cord is very heavy and stiff in the cool mornings. I have run both AC's on 30 amps, but have not done it for any length of time, and I don't think it will do it for long.

Where you live, you will probably only need the two AC's very infrequently.

I say get used to handling the 50 amp cord, it will build character and muscles.

[Aage]

When you think it through, I think you will realize that if it was OK to run two AC units on 30A service, why would Airstream provide a 50A input?

I believe that you run the risk of damaging one or both AC units by doing that. Oddly enough, too little current can harm them.

Perhaps other users with more expertise can calculate if you could use just one AC unit on a 30A input, but I ask you: why run the risk? Is it really that much harder to deploy the 50A cord?

[Rawn77]

Originally Posted by Aage

When you think it through, I think you will realize that if it was OK to run two AC units on 30A service, why would Airstream provide a 50A input?

I believe that you run the risk of damaging one or both AC units by doing that. Oddly enough, too little current can harm them.

Perhaps other users with more expertise can calculate if you could use just one AC unit on a 30A input, but I ask you: why run the risk? Is it really that much harder to deploy the 50A cord?

I think the real question for me was that when I was boondocking at a Walmart, could I use my Honda 3000 inverter generator to run the dual ACs and nothing else?

While up in the North-East I'll rarely need to use 2 ACs but I frequently travel to the southern states in the summer

[Aage]

If you even can do that, it won't last for long before the voltage drops below a useful level. And the same comments for low voltage I made before still stand.

AC is really not usable when boondocking (assuming no AC connection). Heck, you are just now spending a lot of money for your new trailer. Why not spend a few dollars more (for a proper campsite) and give yourself a chance to use all that AC you bought?

[SteveH]

Originally Posted by Aage

When you think it through, I think you will realize that if it was OK to run two AC units on 30A service, why would Airstream provide a 50A input?

I believe that you run the risk of damaging one or both AC units by doing that. Oddly enough, too little current can harm them.

Perhaps other users with more expertise can calculate if you could use just one AC unit on a 30A input, but I ask you: why run the risk? Is it really that much harder to deploy the 50A cord?

We frequently run one AC on a 30 amp circuit with no problems. Have been doing for a long time.

And, it's not too little current that harms them, but too low a voltage which is caused by drawing too much current on a circuit, that will harm the units.

[Minno]

I think you'll find that the 30 AMP Male to 50 AMP Female adapters only supply power to one leg of the 50 AMP female outlet. Only 1 a/c will work.

http://www.adventurerv.net/amp-femal...ter-p-122.html

[SteveH]

Originally Posted by Minno

I think you'll find that the 30 AMP Male to 50 AMP Female adapters only supply power to one leg of the 50 AMP female outlet. Only 1 a/c will work.

http://www.adventurerv.net/amp-femal...ter-p-122.html

You are probably right about the adapter (I haven't actually tried it), but we have a 30 AMP to 50 AMP cord that powers both legs of the circuit.

[bwoodtx]

That is correct. The adapters only supply power to one leg of the 50amp.

[xrvr]

Interesting, you just spent around one hundred thousand dollars for an RV and want to skimp on a campground? If you are staying at a Walmart, etc, then just run the oneAC with your genny, assuming it is at least a 3000. Jim

[Rawn77]

I have been running the 15k AC on my existing Airstream with my Honda 3000 with absolutely no problems.

And believe me when I say; I boondock for the absolute convenience and not to save money. If there were campgrounds every other exit (i.e. Walmart) and it didn't take me 30 minutes to register I would use them. And, I only boondock when en route to the destination.

This Marinco adapter will split 30 Amps to both legs of the onboard 50 Amp circuit panel.

But, it was just a thought......

[Rawn77]

Originally Posted by zigzagguzzi

Interesting, you just spent around one hundred thousand dollars for an RV and want to skimp on a campground? If you are staying at a Walmart, etc, then just run the oneAC with your genny, assuming it is at least a 3000. Jim

Is that what this Forum has come to. My question is not legitimate because of the cost of my RV??
I guess everyone here bought an Airstream because they're poor and looking to do things the cheapest way.

[xrvr]

I see nothing wrong with my post and stand by it. Use the genny and you can stop about sntwhere you want. I also see my first statement as relevant and should not have to defend myself. Jim

[Gene]

If both A/C's surge at the same time, you will likely flip a breaker. That means when you turn them on or they turn themselves on to bring the temp down. I believe each takes about 18 amps to start the compressor (the fan, which can run all the time depending how you set the thermostat, takes little power). So you will draw 36 amps on a 30 amp main breaker, overheat the wires and flip the breaker. If you can get them to never surge together (very hard to do, it will eventually catch up on you), you could get by, but don't use anything else.

If you have other electric appliances, the combination of one A/C and a microwave, toaster, electric heater or something else, may do the same. I haven't had that happen, but smaller appliances used in RV's get by with the A/C more or less.

There's more to it than that, but they won't change the basics.

Gene

[perryg114]

Where in Canada would you need two units at the same time? I have a 31 and a single 15k BTU unit works fine in 90 degree temperatures. If you have some degree of shade and you cover or awning your windows, I can't see the need for both of them. Now if you are in out west where it gets 120 degrees then that is a different story. You might be able to get away with it but you start adding other current draws like the Fridge and the Univolt and lights etc you are going to really be pushing it. You might also burn in the adapter because that is the weak link. You are going to be getting some serious current and voltage spikes. These can cause other things to fail. If the voltage drops the current draw goes up and you can fry one or both compressors. I would expect Canadians to go south in the winter rather than the summer.

Perry

[Rawn77]

Gene
I wasn't sure how many amps each AC consumed when running.
I did know that each time their compressors come on, they will use more amps than while just running; so seeing the 18 amps answers my question. It would be impractical to assume that the two AC's would never cycle their compressors at the same time over a few hours.
Appreciate the answer,
Ron

[Gene]

Ron, every A/C is a bit different, so to be sure, you have to check the electrical plate on the unit. It may be visible once you take off the covers for the foam filters, or you may have to take off the inside cover. That would make it too simple in some cases, so you may have to go on the roof and take off that cover. But, the information provided with the A/C may have the ratings or look up the model numbers on the company website. The model numbers should be on the unit—on the electrical plate or elsewhere. The information that comes with the A/C may be for several units and then you have to figure out which one you have—sometimes the info describes how different units look, sometimes they don't.

Watts = volts x amps. Use 120 for volts. A 20 amp circuit (common for residential receptacles and for an A/C) uses 2,400 watts. An 18 amp appliance uses 2,160 watts. If you only can find out watts for a unit, you can figure out the amps, but the plate should have amps. When you turn on an 18 amp motor, it surges well above that for a very short time (unless you have a slow start unit which costs more and is therefore unlikely). Breakers know that and won't flip right away. The A/C breaker is big enough (20 amp), but the main breaker will be the weak link (either the trailer main or the one on the pedestal).

As for using 2 A/C's in Canada, actually it does get hot and humid there for a few days at least. The Canadian Airstreams come with skis instead of wheels, but 90˚ temps and high humidity are possible even in the Arctic.

Gene

[Jack46]

We have the 2 a/c, 50 amp setup and generally we end up using only one unit. But, unfortunately the heavy 50 amp cord comes with the territory in either situation. Personally, I would not attempt to run both a/c units on a thirty amp cord. It may exist, but in an event, I've never seen a 50 to 30 amp pig tail that connects to the trailer's outlet that would provide for the use of a 30 amp cord.

[Gene]

The pigtail goes on the pedestal. It is only for a CG with only 50 amp service. I have one, but never have had to use it.

Gene

[SteveH]

I don't have one but they make an adapter that will plug into a 30 amp and 20 amp pedestal outlets, and let you use the 50 amp cord. That would probably let you run both AC units. I should get one of those.

http://www.amazon.com/Camco-55025-Po...20+amp+adapter