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dustyone · 02-21-2021, 10:22 PM

If your planning to be in the state or national parks here in the east. Probably not. The older campgrounds out here can't handle it.

Dusty

MtCamper · 02-22-2021, 07:25 AM

I'd recommend you buy a digital multimeter first. As for your question, maybe is the answer. Give it a try and see what it does.
With both running, check an outlet with your multimeter and see how many volts you have. If they both work and you have 108v or fewer, shut one off. You can run on that voltage but you may kill your AC doing so. If you are above 108 you should be OK but 116v or more would be better. Be aware that voltage will drop when the compressor kicks on. One trick is to keep your refer and water heater on propane. And don't run the microwave!

MRUSA14 · 02-22-2021, 07:32 AM

Quote:

Originally Posted by MtCamper

I'd recommend you buy a digital multimeter first. As for your question, maybe is the answer. Give it a try and see what it does.
With both running, check an outlet with your multimeter and see how many volts you have. If they both work and you have 108v or fewer, shut one off. You can run on that voltage but you may kill your AC doing so. If you are above 108 you should be OK but 116v or more would be better. Be aware that voltage will drop when the compressor kicks on. One trick is to keep your refer and water heater on propane. And don't run the microwave!

Bad advice. Voltage is not the main issue here, amperage is. You can have 120 volts but still blow a breaker because you are drawing too many amps.

Like the poster before said, don’t overthink it. When on 30 amps you can easily run just one AC, which may leave you a bit warm in the day but will be more than comfortable to sleep at night.

Old Scout · 02-22-2021, 07:59 AM

Even if your Rig is in perfect condition and you are managing your consumption, the real issue is the quality of power at the CG. The primary reason for "30 amp only" CG's is they are old and outdated.....based on infrastructure and worn equipment--you will be lucky to get 120v and 30 amps. Spending a lot of time figuring out how you can "live" on 29.5 amps probably wont be very productive. IMHO

SailorSam · 02-22-2021, 09:51 AM

Quote:

Originally Posted by Persistent

13 + 13 + 13 = 39 amps. The circuit breaker will trip.

Not necessarily. Breakers are thermal devices and trip due to increase in temperature caused by current flow. Marginally exceeding the amp limit will trip the breaker EVENTUALLY. That is a, a dead short causes a current flow of 100's of amps and the breaker trips almost instantly. Running 33 amps on a 30 amp breaker may continue for seconds to many minutes. You see this everyday - an AC unit at startup draws well over 40 amps, but just for a few milliseconds and the breaker does not trip. So in this case if the microwave is only on for a short period, everything may continue running. On the other hand, an old breaker will heat up faster and trip quicker.

SKP Kirk · 02-22-2021, 09:58 AM

Quote:

Originally Posted by SailorSam

Not necessarily. Breakers are thermal devices and trip due to increase in temperature caused by current flow. .

Circuit breakers are designed with 3 different trip points. What is called "long time", "short time," and "instantaneous." The first is typically about 110% of rated load, the second more like 150% of rated load and instantaneous is usually on the order of 10 X rated load. The actual numbers vary by intended use and manufacturer.

As a circuit breaker ages the trip points begin to fall. An older breaker will often only carry about 80% of rated load if constant.

mrpardee · 02-22-2021, 10:00 AM

I'm on a 30 amp site now and can run both ACs if i don't run anything else. I'm in Fort Meyers so AC is needed. I have my water heater on propane and will turn one AC off if I need to use micro or clothes dryer. I have tripped breaker while running both ACs but was because of water heater. I also have my auto gen start on just in case. I do have the soft start capacitors though and when both are on i'm running at 22 amps.

Randy the sly old fox · 02-22-2021, 11:54 PM

In theory you should not be able to run both AC units - a 50A service is actually more like your house - two 120V and a neutral plus ground. the panel should alternate between the two "phases" of 120V. One AC should be hooked to one phase and the second to the other. The 50 to 30 A dogbone only connects one of the 120 lines. Most RVs I have seen reserve the second AC circuit for the bedroom AC so you can still run the bulk of the unit on a 30A service.

twinboat · 02-23-2021, 03:48 AM

Quote:

Originally Posted by Randy the sly old fox

In theory you should not be able to run both AC units - a 50A service is actually more like your house - two 120V and a neutral plus ground. the panel should alternate between the two "phases" of 120V. One AC should be hooked to one phase and the second to the other. The 50 to 30 A dogbone only connects one of the 120 lines. Most RVs I have seen reserve the second AC circuit for the bedroom AC so you can still run the bulk of the unit on a 30A service.

Dog bones connect the single 30 amp hot to both hots of the 50 amp plug.

All breakers will be powered.

Here is an X Ray view, showing the jumper in the 50 amp side.

Click image for larger version

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KanzKran · 02-23-2021, 07:14 AM

Quote:

Originally Posted by Randy the sly old fox

The 50 to 30 A dogbone only connects one of the 120 lines.

That would describe a 50A shore power to 30A coach dog bone, where only one of the two 50A phase conductors in the pedestal is connected to the single 30A phase conductor in the TT-30R receptacle end.

Randy the sly old fox · 02-23-2021, 09:55 AM

Yep I stand corrected. I realized this morning that I was thinking of the opposite situation - simply because that is where I have found myself being the owner of a rig with only one AC and a 30A set up.

KanzKran · 02-23-2021, 10:38 AM

Quote:

Originally Posted by Randy the sly old fox

. . . myself being the owner of a rig with only one AC and a 30A set up.

I'm in the same situation, and I've found the 50-30A dog bone useful where the 30A receptacle in the pedestal is pretty beat up and loose, while the 50A in the same pedestal is in much better shape. Got that idea here, in fact, and my FIL had already given me a brand new one he had laying around. I carry it in my box of stuff, just in case, and have used it twice so far.