Question about 30 amp vs 50 amp service

[Paleo]

So, assuming I some day get my rv back from the shop and can actually go somewhere in it, I have a question about the electrical. I've had a class C in the past with 30 amp service and it had the typical 30 amp plug. The new class A seems to have the same plug though but has 2 AC units. I was under the impression that 50 amp plugs were different, am I wrong?

[Sully2]

Big Katuna wrote:
My 97 holiday rambler could run two acs on 30a. It had a smart controller.

My '93 Southwind was the same way...30 amp service...2 rooftop AC's.

[Jim]

Eggactly. Doug is correct as usual.

The thing is that plug would not fit a campground 30A outlet for RVs even if it had a round ground...because the angle of the two active legs is different for RV 30A plugs. (One is hot, 120V, the other neutral).

RV plugs and sockets, 30A, are different enough that they have their own designation. They are designated with a TT (for travel trailer).

The 50A plugs and sockets for RVs are the same as home/business appliances though.

[dougrainer]

Old-Biscuit wrote:
30A RV Plug......3 prong


50A RV Plug.....4 prong

The top plug is NOT a 30 amp RV plug but a 220 plug. The top spade should be round. Doug

[wa8yxm]

Well there is a solution for that too but you need some knowledge which I can not impart since I have never worked on a rig like yours.

Basically though here is the procedure.

Somewhere there is a ROMEX cable 12/2 with ground, that run up to one of the air conditioners (Actrually two of them one to each) Usually you deal with the REAR A/C for this mod.

On some RV's you can access the botttom end of this cable in the Generator junction box.. Others. I do not know and that is the knowledge I can not pass on.

On mine (No Load Shedder) I accessed at the breaker.

Disconnect, all 3 wires, HOT, Neutral and Ground

Run a 12 ga wire from the point you disconnected from to a handy spot for an OUTLET

Extend power lead to A/C, again using 12 ga wire, To same spot and put in a plug

Plugged into outlet it works as designed

Unplug and using a 12ga extension cord plug into 20 amp Park outlet and it works.. period.

Notes:
12ga Extension cords.. Sears and K-mart sell one with a push button on the outlet that must be pushed to insert/remove.. I like those

Note 2:
I do not like joining stranded wire to solid wire with wire nuts,, I have had too many of those fail.. If connecting stranded to non stranded I like a good solder job.. But then I was trained in that.

[mowermech]

Our 2001 Fleetwood Southwind is wired for 30 amp service, and has 2 air conditioners. Yes, it has a 5500 watt generator.
It is sitting in the driveway now, plugged in to a 75 foot 10 gauge 30 amp extension cord.
I can run both air conditioners, no problem at all.
Yes, it has a power management system.
Yes, I have used the microwave while both A/Cs were running. It worked.
No, I do not use the electric side of the water heater. I have, however, used a small coffee maker while the A/Cs are running. Again, it worked.
I guess I'm just lucky.

[Rick_Jay]

Ditto Big Katuna,

And if you use 120VAC, you come up with nice round numbers for the maximum available powers of 3,600 watts for 30A and 12,000 watts for 50A service.

~Rick

[Big_Katuna]

depot44 wrote:

JimM68 wrote:
The difference in power is:
30 amps = 3450 watts.
50 amps = 11500 watts.

A 50 amp RV has about 4 times the power available that a 30 amp does.

The forumala for power is P(Watts)=E(Voltage)*I(Current)
Assumming 115 volts:
30 Amps = 3450 watts
50 Amps = 5750 watts
Unfortunately, a 70% increase in current can't produce a 400% increase in power (watts).


Ken

50a RVs have TWO 50a legs. 30a RVs have ONE 30 a leg.

[depot44]

JimM68 wrote:
The difference in power is:
30 amps = 3450 watts.
50 amps = 11500 watts.

A 50 amp RV has about 4 times the power available that a 30 amp does.

The forumala for power is P(Watts)=E(Voltage)*I(Current)
Assumming 115 volts:
30 Amps = 3450 watts
50 Amps = 5750 watts
Unfortunately, a 70% increase in current can't produce a 400% increase in power (watts).

Ken

[dalerussel]

Our rig has 30 amp service with 2 ACs. With our Onan 5500 generator we can run them simultaneously without problems since the back AC runs on a separate genset circuit if we toggle a switch. While parked we have 2 options. We can run on one 30 amp service which allows our ACs (high efficiency with an EMS) to run drawing about 15 and 10 amps. This does not allow much room to run anything else. Our other option, which we use most of the time, is to plug our back AC into a separate 15 amp plug at the pedestal. Our coach was wired with a separate power chord put for the back AC that uses the same circuit and switch used by our generator for the back. In this mode, we have 30 amps in the front with none of them needed for the back AC which has a separate power source. We assume, while not exact, the front AC, the electric water heater, the coffee maker, the microwave and my wife's hairdryer all need about 15 amps. So as long as we only run 2 at a time, we are fine.

[Paleo]

yes, 5500 watt genset. It has the 3 prong plug, and it does have a little "magic box" above the range for switching the ac's to run just the front, just the back or to "pulse" them I think teh guy said.

My only concern is that its retarded hot in texas and running only 1 ac at a time is not going to keep this beast cool, but it seems from the responses that if I only run the ac's and nothing else while driving I can keep both on.

[wa8yxm]

Yes they make 30 amp rigs with 2 A/C..There is either an automatic or manual switch (or both) that selects front or rear A/C. The automatic one will swich back and forth..

If using the generator and FRONT elected you can usually run both.. (NOTE; on some you may need to select REAR)

Does this help.

[Golden_HVAC]

A lot of motorhomes built before 2000 model year had 30 amp service to them. Even if they had two air conditioners. So my guess is that you should have a 5,500 watt generator rated to run both A/C units. The 30 amp service probably will run one A/C at a time, and might have a 'energy management system' to shut off one compressor at a time, and run both fans all the time.

My buddy's 1985 class A DP had a switch in the back to run either the front or rear A/C unless the propane generator was running, when both A/C's could be turned on at once.

If you have a 5,500+ watt generator, then it should have a pair of circuit breakers, typically a 20 and 30 amp breaker. The 30 feeding the main panel, the 20 feeding a relay with just one air conditioner on it.

It is possible, and not all that difficult to upgrade your RV to a 50 amp service. Back in the late 90's Weekend Warrior used to offer a dealer installed optional 50 amp service. Basically it was a 50 amp panel installed in a storage compartment, with a 50 amp main 2 pole breaker, 30 amp feeding the factory installed panel and factory power cord, Then a 20 amp was run to each air conditioner and another 20 amp breaker fed the receptacles near the air compressor in the garage area.

It might take me 45 minutes at Home Depot gathering the supplies, and another 2 hours to install it all in the storage compartment where the electrical cord is located, perhaps another hour if you wanted the electric panel in another compartment.

Good luck,

Fred.

[Tom_N]

You can easily run 2 AC units on 30 amps. But not any other high amp drawing apparatus.

[Old-Biscuit]

30A RV Plug......3 prong


50A RV Plug.....4 prong