30 amp with a/c units?

[turbopilot51]

Can we run both a/c units (15 &13.5) on 30 power? It is 100 degres where we're at and one a/c is barely keeping up.

[joebedford]

I decided to do the same test without the 30A extension. No load was the same: 121.5V

One AC running: 118.2 (vs 116.5)

Two AC running: 114.5 (vs 111.5)

Didn't check startup voltages.

[MEXICOWANDERER]

What
Are
Individual
And
Combined
STARTUP
Voltages?

When one is running and the other is trying to start what kind of voltage are you seeing?

[joebedford]

joebedford wrote:

joebedford wrote:

4) right now my rig is on a weak 15A circuit which will not run even one AC. In a couple of days I'm going to move my rig to where I can plug into 30A. I'll try the two AC test then and let you know.

Just ran both my ACs on one of my 30A plug-ins. No problem but it's quite cool right now - only about 20C. It's going to be back over 30C later this week - I'll try it again and measure the voltage too.

OK - hot today. Ran both ACs on one of my 30A circuits.

Had the standard 50 foot 50A power cord connected to a 50/30 dogbone, then finally a 25 foot 30A extension.

Voltage with nothing running was 121.5V

One AC - 116.5V

Two AC - 111.5V

Changing the fan speed made no difference to the voltage.

[Hoosier_Cruiser]

Both of my air conditioners are heat pumps; therefore, the load of both running on high cool is 22 amps. I have an additional 2 amps load. Probably to maintain charge on batteries. My residential refrigerator adds another 3 amps when starting, but drops off. I cannot run electric water heater even with one of the air conditioners turned off, so I heat water with LPG.

[joebedford]

joebedford wrote:

4) right now my rig is on a weak 15A circuit which will not run even one AC. In a couple of days I'm going to move my rig to where I can plug into 30A. I'll try the two AC test then and let you know.

Just ran both my ACs on one of my 30A plug-ins. No problem but it's quite cool right now - only about 20C. It's going to be back over 30C later this week - I'll try it again and measure the voltage too.

[joebedford]

pianotuna wrote:
How bad is the voltage drop on the 15 amp supply?

joebedford wrote:


4) right now my rig is on a weak 15A circuit which will not run even one AC. In a couple of days I'm going to move my rig to where I can plug into 30A. I'll try the two AC test then and let you know.

The utility supplies us at 122V or sometimes up to 125V (we're in the country). The RV is at about 115V with just the converter running.

[pianotuna]

How bad is the voltage drop on the 15 amp supply?

joebedford wrote:


4) right now my rig is on a weak 15A circuit which will not run even one AC. In a couple of days I'm going to move my rig to where I can plug into 30A. I'll try the two AC test then and let you know.

[Almot]

It's not whether you can "run", it's whether you can "start". Roof A/C draws max 15A, so - yes, you can run at least one. Possibly two on low.

But when it's starting, it draws way more than 30A. So it might not start. Turn everything else off, at least for starting. And watch the voltage.

[dougrainer]

pianotuna wrote:
Hi doug,

I have skin in the game because I am no longer willing to turn off the roof air while I'm cooking on my induction "hot plate".

I have two solutions. One is a Magnum hybrid inverter that allows load support, but can be "tricked" into doing voltage support. It allows me to "dial down" input amperage to the maximum that a 30 amp outlet should be providing (24 amps) for continuous loads.

The other is an autoformer which will prevent damage to the air conditioners (or other loads) from low voltage. (which adversely affects induction cookers, too).

dougrainer wrote:
To the posters that stated yes you can run 2 AC's on 30 amp. YOU have no skin in the game. The correct answer is MAYBE! It all depends on how his RV is wired and if the RV allowed 2 AC units to run on 30 amp. MOST 30 amp RV's do NOT allow 2 AC units to be wired on 30 amp(unless there is an EMS system) Most Towables do not have an EMS system. It depends on the AMP draw of the 2 AC units and IF YOU HAVE AN EMS SYSTEM. It depends on the outside Temps. HIGHER temps will pull MORE amps. So, lets take this example. You are in 80 degree temps. Your AC's pull 13 amps at 95 degrees(spec). At 80 degrees those AC's will only draw 11.5 each for a total of 22 amps. You think great I can run 2 AC units on 30 amp. Lets now go to 100 degree. Those 2 AC units will now draw 13.5 each for a total of 27 amps. Add anything else and you go over the 30 amp threshold. Now, the Breaker will trip? MAYBE. What usually happens is, the line voltage drops and the wiring heats up. LOOK at the 30 amp shore cord end. WHY do they seem to look burnt and corroded/pitted? Because you have been overloading the power supply. Some CG's may have larger than 30 amp breakers on that 30 amp supply. Then add in the fact that most that run 2 AC's on 30 amp use a 50 to 30 amp dogbone adapter. IMO, DO NOT ADVISE PEOPLE TO RUN 2 AC UNITS IF YOU HAVE NO KNOWLEDGE OF THE SYSTEM THEY HAVE. Doug

What I meant by skin in the game is simple. Posters that state unsafe things do NOT have to suffer the consequences or COST when bad things happen. Doug

[pianotuna]

Hi doug,

I have skin in the game because I am no longer willing to turn off the roof air while I'm cooking on my induction "hot plate".

I have two solutions. One is a Magnum hybrid inverter that allows load support, but can be "tricked" into doing voltage support. It allows me to "dial down" input amperage to the maximum that a 30 amp outlet should be providing (24 amps) for continuous loads.

The other is an autoformer which will prevent damage to the air conditioners (or other loads) from low voltage. (which adversely affects induction cookers, too).

dougrainer wrote:
To the posters that stated yes you can run 2 AC's on 30 amp. YOU have no skin in the game. The correct answer is MAYBE! It all depends on how his RV is wired and if the RV allowed 2 AC units to run on 30 amp. MOST 30 amp RV's do NOT allow 2 AC units to be wired on 30 amp(unless there is an EMS system) Most Towables do not have an EMS system. It depends on the AMP draw of the 2 AC units and IF YOU HAVE AN EMS SYSTEM. It depends on the outside Temps. HIGHER temps will pull MORE amps. So, lets take this example. You are in 80 degree temps. Your AC's pull 13 amps at 95 degrees(spec). At 80 degrees those AC's will only draw 11.5 each for a total of 22 amps. You think great I can run 2 AC units on 30 amp. Lets now go to 100 degree. Those 2 AC units will now draw 13.5 each for a total of 27 amps. Add anything else and you go over the 30 amp threshold. Now, the Breaker will trip? MAYBE. What usually happens is, the line voltage drops and the wiring heats up. LOOK at the 30 amp shore cord end. WHY do they seem to look burnt and corroded/pitted? Because you have been overloading the power supply. Some CG's may have larger than 30 amp breakers on that 30 amp supply. Then add in the fact that most that run 2 AC's on 30 amp use a 50 to 30 amp dogbone adapter. IMO, DO NOT ADVISE PEOPLE TO RUN 2 AC UNITS IF YOU HAVE NO KNOWLEDGE OF THE SYSTEM THEY HAVE. Doug

[joebedford]

Couple of things:

1) my 5th wheel is wired for 50A but does not have an EMS.

2) turn the converter off before you attempt to run two ACs - it can draw a lot.

3) if your THERMOSTAT is like mine, it will not start both ACs at the same time - there is a time lag of about 30 seconds. No need to set different temperatures.

4) right now my rig is on a weak 15A circuit which will not run even one AC. In a couple of days I'm going to move my rig to where I can plug into 30A. I'll try the two AC test then and let you know.

5) I guess this is more than a couple of things.

[dougrainer]

Sober person posts---Can I get drunk and drive? Alcoholics respond, SURE, we do it all the time and nothing bad ever happens. Sober person then thinks, great, I can do it also. To the posters that stated yes you can run 2 AC's on 30 amp. YOU have no skin in the game. The correct answer is MAYBE! It all depends on how his RV is wired and if the RV allowed 2 AC units to run on 30 amp. MOST 30 amp RV's do NOT allow 2 AC units to be wired on 30 amp(unless there is an EMS system) Most Towables do not have an EMS system. It depends on the AMP draw of the 2 AC units and IF YOU HAVE AN EMS SYSTEM. It depends on the outside Temps. HIGHER temps will pull MORE amps. So, lets take this example. You are in 80 degree temps. Your AC's pull 13 amps at 95 degrees(spec). At 80 degrees those AC's will only draw 11.5 each for a total of 22 amps. You think great I can run 2 AC units on 30 amp. Lets now go to 100 degree. Those 2 AC units will now draw 13.5 each for a total of 27 amps. Add anything else and you go over the 30 amp threshold. Now, the Breaker will trip? MAYBE. What usually happens is, the line voltage drops and the wiring heats up. LOOK at the 30 amp shore cord end. WHY do they seem to look burnt and corroded/pitted? Because you have been overloading the power supply. Some CG's may have larger than 30 amp breakers on that 30 amp supply. Then add in the fact that most that run 2 AC's on 30 amp use a 50 to 30 amp dogbone adapter. IMO, DO NOT ADVISE PEOPLE TO RUN 2 AC UNITS IF YOU HAVE NO KNOWLEDGE OF THE SYSTEM THEY HAVE. Doug

[time2roll]

Turn fridge and water to propane only and give it a go.
Nothing will be harmed to try once. Use low fan speed.
Microwave or hair dryer will trip breaker so don't.

[pianotuna]

Get an autoformer to support low voltage that running both may cause. That may allow you to run both air units at the same time.