50 amp on a 30 hookup - what do you lose?

[mgscott4]

Your right cbeierl, I used and ohm meter and checked out my 50-30 adapter and the hot lead is connected to both hot leads on the 50 end.

I wonder how the coach knows when I'm on 30 amp and won't turn on the rear AC?

I do know the 20 amp breaker on my 5.5kw Onan generator feeds my rear AC and electrical water heater and I can't turn them both on at the same time or it trips. The 30 amp breaker on the generator feeds the rest of the coach.

[jzick]

You can do fine with 30 Amp service if you do not mind watching your electric use (alternating ACs on and not using heavy draw appliances at the same time). After living off grid for 25 years and getting tired of all the work that entails, DW and I are power spendthrifts and try to avoid 30 amp only places. We are exceptions. Most people do great with just 30 amps.

[Wizard]

Originally Posted by mgscott4

Your right cbeierl, I used and ohm meter and checked out my 50-30 adapter and the hot lead is connected to both hot leads on the 50 end.

I wonder how the coach knows when I'm on 30 amp and won't turn on the rear AC?

I do know the 20 amp breaker on my 5.5kw Onan generator feeds my rear AC and electrical water heater and I can't turn them both on at the same time or it trips. The 30 amp breaker on the generator feeds the rest of the coach.

Your coach can tell the difference between 110 source ( 30A ) and a 220v connection (50A ), my EMS will display which source it has available and manage the loads. Also my ammeter will only display amps when on 30 amp, is turned off when on 50 amp

[wa8yxm]

Eva Gabore rules (Eva Gabore played Mrs. Douglass on a TV shows called Green Acers, ehs was in the habit of plugging in too many appliances and blowing the farm's generator)

Big Ticket items include. Air Conditioners, Microwave, Water heater, Space heaters and if you just parked and the batteries are low.. The converter (It goes away when batteries fill up)(

Rule are:

20 amps = 1 big ticket item,, YOu may also be able ro run a tv or two.
30 amps - 2 big ticket items You will be able to run Televisions and such as well.
50 amps is SIX big ticket items.. You don't have that many. Basically EVERYTHING YOU GOT.


Suggestion.. there used to be a company Power Solutions RV,, www.psrv.net, Of late I have not been able to access their web page.

They sold an adapter, it was basically what I call a "Break out box" that.. Well let me describe how to build somethign like ti.

Get a 12ga extension cord (Sears and K-mart sell them with locking outlets, Lowes, and HOme Depot have them with standard outlet end.

Cut it in half

Now find the circuit breaker that feeds the rear A/C. remove the wire from it and remove the other two wires assoicated with that cable.. Remove these from the box to a Jniction box. Hook the half of the cord with the PLUG to these wires properly securing the connections with wire nuts and tape.

Hook the outlet end of the cord to the circuit breaker and neutral/ground bus bars in the breaker box.

The plug/outlet can be routed to an exterior compartment (Somewhere you can run a cord to)

Using a 12 ga cord, plug this into the 20 amp outlet on the park box.

YOu now have a completly INDEPENDENT power to the rear A/C. so... Using the rules above.. It does not count.

[sadrand]

Thanks to everyone for the great information. I feel much better about having a 50 amp coach now!

[firedoc]

I have an adapter thst has 2 30amp male ends and one 50 amp female end. I plug one 30a into my pedistal and one 30a into my neighbors (empty space) pedestal. This works (hopefully) where I need to use it. (No one at adjacent site). Have not tried it yet but have a volunteer position coming up where I hope it works.

[The Driver]

Originally Posted by Wizard

Your coach can tell the difference between 110 source ( 30A ) and a 220v connection (50A )....

50amp plugs provide two legs of 110v, but that's NOT the same as 220v!

[Dave78Chief]

Actually 50 amp service is 220VAC. It is two 110VAC 50A circuits 180 degrees out of phase.

Ever wonder why if each leg (L1/L2) is providing 50 amps each why the Nuetral leg wire size is not sized for 100 amps? It's because this is 220VAC service and the current is flowing back and forth over the L1/L2 leads in the shore power cable. In fact, there is essentially no current on the shore power Nuetral lead when connected to 50 amp service.

Additionally, the Main House Breaker Panel in a stick house works the same way.

When you use a 30 amp dog leg adaptor on a 50 amp coach, you are splitting the 30 amps between the 50 amp L1/L2 leads (L1/L2 jumpered tghether in dog leg). Because that is now single phase power, the shore power Nuetral lead does have current on it.

Dave

[Barbaraok]

Originally Posted by mgscott4

If you want to know exactly what you lose, just look at you circuit breaker panel. The 50 amp main breaker has a connected double pull handle, one is for "line 1" hot and the other is for "line 2" hot. Then every other breaker is fed from "line 1" and every other breaker is fed from "line 2" alternating. 30 amp service only line 1 so every other breaker is not hot on 30 amp.

On my rig, line 2 powers my rear AC and electric water heater. That is all I lose when connected to 30 amp or even 20 amp for that matter.

Everything on ours works just fine on 30 amps no matter which line it is on in the breaker panel. We always run the water heater and frig on electric and then we can add ONE energy pulling item, air conditioner, microwave, washer/dryer, etc., and if we have the dryer going and need to use the microwave, then we stop the dryer and run the microwave, then restart the dryer.

Big difference you notice is that with 50 amps, we never have to think about what else is running as long as it is on a different circuit.

Barb

[HotMech]

Originally Posted by The Driver

50amp plugs provide two legs of 110v, but that's NOT the same as 220v!

It is exactly that. it is truly, called, and is, 50A 220V, yes, it is just like your stick house. Other than, you stick house probably has 200A 220V.
But still the same thing. Most "50A" coaches, are not wired for anything using 220V, but it is there, that's how the EMS figures out what you have available. When you use an adapter, down to 30A, it supplies power to both legs, "in Phase" 30A 110V When you are connected to a full 50A post, there is two legs, each at 50A 110V 180deg out of phase, hence the 220V. Very confusing I know, but all very true. But just to make it even more confusing, Your generator adds to this confusion. most gas coaches of the recent years have an Onan 5500. It supplies Two circuits in phase, at 110VAC some have one 30A and one 20A circuit, some have two 30's, but still both in phase, but a total of only 45.8A at sea level and 70deg F.
Some coaches have larger 7k and 8k Diesels. but again, they mostly only have two circuits, in phase. So the 7k Onan Quiet Diesel, is only about 55 or 60A (I don't have my book in front of me sorry) total. So still less than a full 50A Shore line.
Chew on that for a while. hehe.
K.

[M&EM]

Originally Posted by Dave78Chief

In fact, there is essentially no current on the shore power Nuetral lead when connected to 50 amp service.

Dave

Dave I respectfully disagree. There usually is current in the neutral to the degree that one or the other of each phase(leg) is loaded differently..

Neutral current would be zero if the load were a 220 volt type(across both phases(legs)). This is uncommon in a typical 50 Amp wired motor home.

If, for example, only one AC were running, all the current it draws can be measured on the neutral. A two AC motor home is usually wired with one AC on each leg.

If both AC s were running, their currents may be equal and 180° out of phase. Then there would appear to be no current flowing in the neutral.

Marty

[Wayne M]

Dang!
This is getting to be just as much fun as "driver's licenses."

[Dave78Chief]

Marty,
Your correct. Thanks for bringing that out. Main point I was making is that load is shared between L1/L2 leads so that the Nuetral lead does not have to be sized for 100 amps. If, the same phase was used on each L1/L2 leg, then the Nuetral lead could be having to pull twice the number of amps it is designed for. This is why it has to be a a normal 220VAC style circuit (2 110VAC leads that are 180 degrees out of phase). People grasp and retain the idea of excessive current load (L1 50A + L2 50A = 100A total) on Nuetral lead easier than phase relationship as the reason why it has to be 220VAC.

Dave

[HD4Mark]

You can also use one of these Cheater Box Some of us have made these as I did for much less. If you are comfortable with working with electric they are a bargain compared to buying one. You can plug one end into the 30A at your site and the other into the 20A (standard plug using a 30 to 20 adapter). It will not work if the 20 is a GFCI. Or plug one into the 30 at your site and the other into another pedestal. Some "ifs" here like hopefully both circuits you use are not actually one in the same.

Your new rig should have some kind of EMS or energy management system. We found out that when plugged into a 30A it may decide it needs to shed some load. In our case one of the first things it sheds is the electric hot water heater. That meant one morning with the gas hot water shut off no hot water to shower. No big deal since the gas will heat the tank quickly.

It is all stuff you will get used to so don't hesitate buying a 50A MH.