Home Electrical Hook Up
We have a 30 amp breaker for our RV at our home. Can you run two air conditioners in your Rv with a 30 amp? I am afraid to try it in fear of it creating a fire or damage to RV or home. Thank you for ...
Forum Discussion
OP, are you saying you have a 30 amp outlet already, but not an RV yet with two AC units and wondering if a 50 amp RV would get by at 30 amps with two AC units?
As mentioned previously, it depends on a few factors. You might get lucky, you might not. You can do things to improve the chances of it working with two. Proper voltage is critical. With AC units, as the voltage drops, AC units draw more current. AC units are rated to run at a nominal 120 volts. There are a number of sources of voltage drop from where your house connects to the power utility wiring on the street up to the power connection at the AC units themselves.
If you were to look at the AC unit electrical specs, you would probably find that by calculation, running two simultaneously is not possible on 30 amps. By code you would size the "main" breaker in the RV by taking the full load running current of the 1st AC unit (say 12 amp) and add the breaker rating for the 2nd (they're sized to min. to allow AC unit to startup) which would be 12+20 = 32 amps. So a 30 amp breaker "might" just make it. Note that this is at 120 volts nominal so as the voltage goes down, it will reach the point that it will take out the 30 amp breaker. In addition, you could also have other loads running in the RV like converter and fridge (on 120V) that will contribute to lower voltage. This is why it "depends"... Some will find it works, some won't.
If the voltage at the house panel is less than 120 volts, you have a lower chance. In the summer, if many other homeowners are running AC units in their homes, the voltage can drop. Can also drop in rural areas.
If the 30 amp receptacle isn't close to the house panel, you could have some voltage drop there. For longer runs, larger gauge wiring helps. If you need an extension cord, use min. #10 AWG, but even then it may not be enough.
Make sure plug blades on a shore power cord are kept clean. Dirty = voltage drop and heat. Never plug the shore power into a live outlet. Install a disconnect switch at home or shut a breaker off.
You may get the first AC unit running, but the second may not because an AC unit momentarily draws up to around 6 times the running current. The running current of the first unit + the 2nd at 6 times FLA may thus trip a 30 amp breaker. You could try a hard start capacitor if marginal to reduce the momentary inrush current. Also, make sure no other loads are running when trying to start the 2nd AC. Watch voltage level inside the RV *IF* you get two running. Running other loads (converter an exception if batteries charged) may not be possible.
Install a permanent voltmeter inside the RV to monitor the voltage. The best thing would be to install an EMS unit as it will automatically shut the power off it the voltage gets too low. Voltage under 105 will cause damage and eventual failure. Watch the reading on the voltmeter when you try and start the 2nd AC.
It is even possible, depending on the size of your house panel and total load calculation, that running two AC units in the RV is technically not possible and a house main breaker could trip when trying to start a 2nd AC unit in an RV. Having a 50 amp outlet (which is like 100 amps at 120V) could have an even higher possibility of tripping a house main breaker, esp. if you ran a bunch of other loads in the RV. If submitting a load calculation to the authority having jurisdiction, an RV outlet may not even be allowed, but I have yet to read of anyone doing this when installing an RV outlet (may not be exactly a legit. install).
ps: I did try to make this brief. :(
As mentioned previously, it depends on a few factors. You might get lucky, you might not. You can do things to improve the chances of it working with two. Proper voltage is critical. With AC units, as the voltage drops, AC units draw more current. AC units are rated to run at a nominal 120 volts. There are a number of sources of voltage drop from where your house connects to the power utility wiring on the street up to the power connection at the AC units themselves.
If you were to look at the AC unit electrical specs, you would probably find that by calculation, running two simultaneously is not possible on 30 amps. By code you would size the "main" breaker in the RV by taking the full load running current of the 1st AC unit (say 12 amp) and add the breaker rating for the 2nd (they're sized to min. to allow AC unit to startup) which would be 12+20 = 32 amps. So a 30 amp breaker "might" just make it. Note that this is at 120 volts nominal so as the voltage goes down, it will reach the point that it will take out the 30 amp breaker. In addition, you could also have other loads running in the RV like converter and fridge (on 120V) that will contribute to lower voltage. This is why it "depends"... Some will find it works, some won't.
If the voltage at the house panel is less than 120 volts, you have a lower chance. In the summer, if many other homeowners are running AC units in their homes, the voltage can drop. Can also drop in rural areas.
If the 30 amp receptacle isn't close to the house panel, you could have some voltage drop there. For longer runs, larger gauge wiring helps. If you need an extension cord, use min. #10 AWG, but even then it may not be enough.
Make sure plug blades on a shore power cord are kept clean. Dirty = voltage drop and heat. Never plug the shore power into a live outlet. Install a disconnect switch at home or shut a breaker off.
You may get the first AC unit running, but the second may not because an AC unit momentarily draws up to around 6 times the running current. The running current of the first unit + the 2nd at 6 times FLA may thus trip a 30 amp breaker. You could try a hard start capacitor if marginal to reduce the momentary inrush current. Also, make sure no other loads are running when trying to start the 2nd AC. Watch voltage level inside the RV *IF* you get two running. Running other loads (converter an exception if batteries charged) may not be possible.
Install a permanent voltmeter inside the RV to monitor the voltage. The best thing would be to install an EMS unit as it will automatically shut the power off it the voltage gets too low. Voltage under 105 will cause damage and eventual failure. Watch the reading on the voltmeter when you try and start the 2nd AC.
It is even possible, depending on the size of your house panel and total load calculation, that running two AC units in the RV is technically not possible and a house main breaker could trip when trying to start a 2nd AC unit in an RV. Having a 50 amp outlet (which is like 100 amps at 120V) could have an even higher possibility of tripping a house main breaker, esp. if you ran a bunch of other loads in the RV. If submitting a load calculation to the authority having jurisdiction, an RV outlet may not even be allowed, but I have yet to read of anyone doing this when installing an RV outlet (may not be exactly a legit. install).
ps: I did try to make this brief. :(
