I am looking for some advice on RV 50 Amp service versus 30 amp.

[LarryJForman]

Because I am going 100% electric appliances, I want to maximize the amps I can pull from shore power. I want to be able to use either 30 amp or 50 amp service. When using 50 amps, I am thinking that I might be able to use one of the 50 amp lines dedicated for the roof A/C and the other line for everything else. This means that the 50 amp service lines will be unbalanced. Will that work OK or will the 50 amp breaker trip? When using 30 amp service, I will use a modified 30 amp to 50 amp adapter with one of the 50 amp lines separated and run only to a relay. I can have a relay trip when that line has no voltage and switch the roof A/C onto the rest of the circuit breakers. The idea is that for 50 amps I don't need to be quite so careful with power usage than when I have 30 amp shore power. I hope to have 50 amp service most of the time, but be prepared if only 30 amp service is available. Any suggestions appreciated.

 

[time2roll]

50 amps is a ton of power. Unbalanced is fine but I don't see the point. A 30/50 adapter connects both 50 amps mains to the 30 amp hot so everything is powered up. Yes some energy management will be needed on 30 amps. Even most 30 amp RVs need to be careful of power usage. I don't get how the modified adapter and relay helps anything.

 

[LarryJForman]

Thanks for your comments. The idea is to separate the possibly long running roof A/C power and that approximately 14 amps from the rest of the 50 amps. By splitting it off, I have the entire other 50 amps to use for the induction cooktop, the microwave, the hot water heater, the coffee pot and the refrigerator and anything else. It means that I don't need to be nearly as careful about running out of amps.

 

[CamoGreg]

With 50amp service, you won't need to add anything on even the biggest RV. 50a provides something like 12500 watts.

I can power everything you mention in my 42' 5th wheel and more. Including 2 chest freezers, multiple space heaters/electric fireplace. I can run dual 15,500 btu A/C units and use the microwave, an air fryer and an electric smoker, run a 120V washing machine while the freezers, fridge, hot water tank, computers and TV sets don't miss a beat.

Lots of folks in big 5th wheels run basically the same loads and 3 a/c units off a single 50amp plug.

Now they make dual 30amp plugs that will also tie into additional 20amp outlet with an adapter. (Or mooch off of another pedestal) But it still falls well short of a 50amp service.

50a x 240V = 12,000W

30a x 120V = 3,600W
Even adding a 20a kicker: 20a x 120v =2,400w

While they are both 50amps:

Split phase 50A = 12000W
Single 30A+20A = 6000W

Do you currently have an RV with 50amp split phase service?

 

[LarryJForman]

With 50amp service, you won't need to add anything on even the biggest RV. 50a provides something like 12500 watts.

I can power everything you mention in my 42' 5th wheel and more. Including 2 chest freezers, multiple space heaters/electric fireplace. I can run dual 15,500 btu A/C units and use the microwave, an air fryer and an electric smoker, run a 120V washing machine while the freezers, fridge, hot water tank, computers and TV sets don't miss a beat.

Lots of folks in big 5th wheels run basically the same loads and 3 a/c units off a single 50amp plug.

Now they make dual 30amp plugs that will also tie into additional 20amp outlet with an adapter. (Or mooch off of another pedestal) But it still falls well short of a 50amp service.

50a x 240V = 12,000W

30a x 120V = 3,600W
Even adding a 20a kicker: 20a x 120v =2,400w

While they are both 50amps:

Split phase 50A = 12000W
Single 30A+20A = 6000W

Do you currently have an RV with 50amp split phase service?

Hi CamoGreg,
I really appreciate your comments. To answer your question, NO, my RV is now only a 30 amp single phase. That said, I am building the circuit breaker panel and I want to be able to have more than 30 amps, but also single phase. I was unaware of the 30 +20 adapter. Also, I could wire my custom breaker box so that the roof A/C would be dedicated to the 20 amp circuit and everything else for the other phase of the 50 amp service. Essentially you showed me an approach that gets me where I was hoping to go. This means that one phase of 50 amps is 6000W and so is single 30A+20A. This will help me not worry so much about 30 Amp limit I was concerned about. Well done. Many thanks, Larry

 

[TacomaJoe]

Thanks for your comments. The idea is to separate the possibly long running roof A/C power and that approximately 14 amps from the rest of the 50 amps. By splitting it off, I have the entire other 50 amps to use for the induction cooktop, the microwave, the hot water heater, the coffee pot and the refrigerator and anything else. It means that I don't need to be nearly as careful about running out of amps.

Keep in mind that a 50A RV service has two 50A legs (total 100A) plugging into a 30A service will give you less than one third the power.

 

[LarryJForman]

Keep in mind that a 50A RV service has two 50A legs (total 100A) plugging into a 30A service will give you less than one third the power.

Yes, I understand. I am planning for flexibility when 50 A RV service is not available, like at home or some RV sites with only 30A and 20A. I want to be able to plug in for maximum power for those situations. For most RV parks I will just go 50 A, but when that does not work or is not available then 30A and 20A would work fine. 30A alone is somewhat limiting if I need the A/C to be working fine, and that is when adding 20A will really help in not having to juggle some of the power hungry appliances. For likely 90+ percent of the time I plan on using just a single phase of the 50A and that will work great. Thanks for the words of caution.

 

[GlenC]

I went with a Victron Multiplus 2 just for this reason. I believe it will function if I'm plugged into 240V/50A, 120V/50A, 120V/30A, 120V/20A.... I will just be limited to the amount of power available.

 

[time2roll]

The 30 + 20 adapter will trip a GFCI outlet every time. Virtually all US RV parks that have a 20 amp outlet will be GFCI protected.

Just swap out the 30 amp panel for 50 amps and get a 50 amp cord. Balance the panel and use less power when on 30 amps. Thousands of RVs do this every day with no issues no special equipment.

The 50/30 adapter will supply both sides of the panel with power so anything can operate normal to the limit of 3600 watts total. Just limit what you turn on. That A/C draws no power if turned off. I recommend the fridge and water heater should be set to propane only when on 30 amps.

 

[Freqz]

Hi CamoGreg,
I really appreciate your comments. To answer your question, NO, my RV is now only a 30 amp single phase. That said, I am building the circuit breaker panel and I want to be able to have more than 30 amps, but also single phase. I was unaware of the 30 +20 adapter. Also, I could wire my custom breaker box so that the roof A/C would be dedicated to the 20 amp circuit and everything else for the other phase of the 50 amp service. Essentially you showed me an approach that gets me where I was hoping to go. This means that one phase of 50 amps is 6000W and so is single 30A+20A. This will help me not worry so much about 30 Amp limit I was concerned about. Well done. Many thanks, Larry

I have my current RV wired this way: 30A shore power goes to Victron 24/3000 which feeds a 50A sub panel with AC on a 20A circuit and and the old main panel on a 30A circuit. This way, I can use the multiplus to assist with batteries/solar when I’m drawing over 30A (or 15 or what ever I set it to). I can comfortably moochdock on a 15A plugin with my 1000W of solar when it’s 100° out.

 

[Grabcon]

Okay Larry I have read this thread several times now and still somewhat confused on what you are trying to do and the responses that folks are giving you.

A normal 50amp RV circuit comes into the RV with 2 hot wires, a common and a ground. Each hot is 120 volts for a total of 240 volts at 100 amps. When the wires get to the AC distribution panel they are split into 2 - 120 volt legs at the 50 amp breaker in the distribution panel. The panel has 2 bars that alternate the other breaker for line 1 and line 2. Each bar is 120 volts. But that does not mean you have a 100 amps. You still only have a maximum of 50 amps in per leg.

In my RV I have 2 AC units, front and rear. Each is on a different line, front is line 1, rear is line 2. Now it is my understanding that using a 30 amp to 50 amp adapter there only be one hot line going to the RV distribution panel. I have also heard that if you go to a 20 amp adapter (basically a 20 to 30 to 50 amp daisy chain) that if there is a GFCI you will trip the GFCI. Be careful doing this I have seen several of the plug type adapters arc at the plugs and cause breakers to trip. Use the dog bone type of adapter.

 

[John Frum]

Hope this helps
30 amps @ 120VAC = 3600 watts
50 amps @ 240VAC = 12000 watts

 

[triplethreat]

Okay Larry I have read this thread several times now and still somewhat confused on what you are trying to do and the responses that folks are giving you.

A normal 50amp RV circuit comes into the RV with 2 hot wires, a common and a ground. Each hot is 120 volts for a total of 240 volts at 100 amps. When the wires get to the AC distribution panel they are split into 2 - 120 volt legs at the 50 amp breaker in the distribution panel. The panel has 2 bars that alternate the other breaker for line 1 and line 2. Each bar is 120 volts. But that does not mean you have a 100 amps. You still only have a maximum of 50 amps in per leg.

In my RV I have 2 AC units, front and rear. Each is on a different line, front is line 1, rear is line 2. Now it is my understanding that using a 30 amp to 50 amp adapter there only be one hot line going to the RV distribution panel. I have also heard that if you go to a 20 amp adapter (basically a 20 to 30 to 50 amp daisy chain) that if there is a GFCI you will trip the GFCI. Be careful doing this I have seen several of the plug type adapters arc at the plugs and cause breakers to trip. Use the dog bone type of adapter.

The bolded part of your statement above is wrong. 240V at 100 amp = 24,000 watts.....and that is not correct. The split phase system on a trailer is two 120V legs (with reference to the neutral) and are rated at 50 amps each.... 120volts x 100 amps or 120volts times 50 amps each = 12,000Watts

 

[Grabcon]

It should be 50amp. oops

 

[CamoGreg]

It's a little confusing. My understanding:
The issue is his RV is only a 30A rig.
But he can plug into a 50A service (adapter?) and get more watts on the one leg allowing use of all the appliances and his a/c unit. He can't do that on a standard 30A service where the watts are lower.

1 leg of 50A split phase = 6000W
Standard 30A = 3600W

 

[John Frum]

It's a little confusing. My understanding:
The issue is his RV is only a 30A rig.
But he can plug into a 50A service and get more watts on the one leg allowing use of all the appliances and his a/c unit. He can't do that on a standard 30A service where the watts are lower.

1 leg of 50A split phase = 6000W
Standard 30A = 3600W

Do we know what the busbar in the ac distribution center is rated for?
I would guess is its a 30 amp panel its busbar will not likely be specced much higher that 30 amps.

 

[CamoGreg]

---

Do we know what the busbar in the ac distribution center is rated for?
I would guess is its a 30 amp panel its busbar will not likely be specced much higher that 30 amps.

I don't know. I have full 50A split phase service. That's why the OP question was confusing to me. I assume as you do he's trying to push more power than the rig is designed for.

 

[triplethreat]

The existing 30A panel in the RV is 120V only...one hot, one neutral, and the ground. There should also be a 30A single pole breaker in that panel. Given that info, plugging into a 50A plug at an RV park while using the proper adapter will still only provide 30 amps of current because everything in the panel is feed from the 30A main breaker in that panel. The 50A to 30A adapters are wired so that one of the blades that plugs into the shore power does absolutely nothing....there is no wire attached to one of the two hot blades on the 50A plug with that adapter.

 

[John Frum]

The existing 30A panel in the RV is 120V only...one hot, one neutral, and the ground. There should also be a 30A single pole breaker in that panel. Given that info, plugging into a 50A plug at an RV park while using the proper adapter will still only provide 30 amps of current because everything in the panel is feed from the 30A main breaker in that panel. The 50A to 30A adapters are wired so that one of the blades that plugs into the shore power does absolutely nothing....there is no wire attached to one of the two hot blades on the 50A plug with that adapter.

Some panels have busbars that are rated for 50 amps per leg.
If that were the case then the 30 amp master breaker could be swapped for a 50 amp breaker.
That would only make sense if some branch circuits were added.
I would be very surprised if a manufcturer would wire enough loads into the existing panel to pop a 30 amp breaker under normal operation.

 

[CamoGreg]

Again, I don't know all of how the OP has his service setup.
Only:
-30A RV
-50A pedestal provides enough power but not true 50A split phase.
-Asking to increase power when only 30A pedestal is available.