2 30amps on pigtail for 50 amp Class A

[JVH]

I hope I don't confuse the issue here. Part of the confusion is that some people think that RVs are like houses. And in some ways they are. In a home a 50 range plug is two 120 volt 50 Amp legs out of phase. So If you connect a meter across the hot leads you get 240 volt at 100 amps.
The rest of the circuits are divided between the two legs coming into your house and are all 120 volt.

Unless things have changed, there are no 240 devices or outlets in an RV.
Think of your RV as a house with two 25 amp sides in your circuit breaker box.
The two side of the 50 Amp plug feeds each side of the box.

If you have ever used a 30 amp to 50 amp adapter in a park that had no 50 amp outlets to use. The adapter simply wires the one 30 hot lead from the the plug to both sides of the 50 female you plug your cord in. Mostly everything works unless you turn on too much high amp items like A/C units.

If you have an adapter that is two 30 amp plugs to one 50 female it will work fine as long as the pedestal is two 30 amp receptacles with 30 amp circuit breakers.

The only thing is that I would put a voltage minder / protector at the 50 amp end.
Some older parks may not have a heavy enough feed if many people start drawing like this and it may cause brown outs and damage your equipment.

Hope this helps.

[lewisedge]

Originally Posted by phlatkat

Folks,

I seem to be the king of electrical questions with my new class A. We stay at a park most of the summer and we just moved to a new pad. This particular one has an old power box with two 30 amp plugs. We need 50 amps for our rig. I've been told this box only has one leg and making it a 50 amp would be difficult. It has been suggested to use a twin 30 pig tail to 50 as a substitute. I've noticed several of the 5th wheels are set up this way. Will this work with my rig? Will it cause any damage or problems with operation long term? We're in Oklahoma so we will definitely need that second air in July and August. Any help appreciated.

Jay

If your RV has a power management system and "if" both 30-amp plugs are drawing from the same side of a 240 volt circuit, your RV's power management system may not "allow" you to draw more than 30-amps total. My Winnebago Itasca Sunova 33C works that way.


If you have a voltmeter and are able to measure the voltage between the "hot" pins of both of your 30-amp outlets you will either measure zero volts if they are both drawing from the same hot leg and approximately 240 volts if they are drawing from opposite sides of a 240 volt leg. If you measure 240-volts you may be able to power everything you need by using the plug splitter. I can run every electrical device in my motorhome on less than 25-amps per leg with a 240 volt connection.


I have often used my plug splitter with two 30 amp connections by using a 30-amp extension cord to hook into an adjacent campsite that is vacant to get the 240 volts. On campsites with 20-amp non-GFI sockets I can use that socket for the other side of the connection using this splitter and a 30-amp to 20-amp plug adapter.

[JMVAIL]

If your worried about needing to run two air conditioning units on a 30 amp circuit then you should get an Easy Start from Microair installed in each unit this would resolve your issue

Go to microair.net for the details good luck stay safe and wash your hands

[bobfrommaine]

Yup, as long as the 2 30A circuits are on separate breakers, and you make/find a 30/30 to 50A adapter, your coach will see that as 50A.
Bob '14 37F Adventurer; Jeep toad

[twinboat]

Originally Posted by JVH

I

So If you connect a meter across the hot leads you get 240 volt at 100 amps.


Think of your RV as a house with two 25 amp sides in your circuit breaker box.
The two side of the 50 Amp plug feeds each side of the box.

Hope this helps.

These statement don't help.

First one is wrong, its 50 amps at 240 volts. There is no 100 amps. It can be split into two 120 volts lines at 50 amps each.

Your RV breaker panel has a double 50 amp breaker. There are no 25 amp breakers. L1 is 50 amp and L2 is 50 amp.

[theoldwizard]

Originally Posted by JVH

In a home a 50 range plug is two 120 volt 50 Amp legs out of phase. So If you connect a meter across the hot leads you get 240 volt at 100 amps.

WRONG ! You get 240V @ 50A.

Remember we are talking about POWER which is V x A (true for DC, close enough for AC).[/QUOTE]

[theoldwizard]

Originally Posted by bobfrommaine

Yup, as long as the 2 30A circuits are on separate breakers, and you make/find a 30/30 to 50A adapter, your coach will see that as (240V @) 50A.

Maybe, maybe not. If each 30A circuit is on a different leg then you will get 240V @ 30A. If both feed are on the same leg, any 240V appliance will see 0V !

[RichardJ]

Originally Posted by cavie

The problem with that adapter is the average Joe does not know that those two 30's have to be on different legs of of a split phase service. And also would not know how to test to see if they are. It takes a volt meter that I find not many RV'ers have or know how to use.

Only if you are needing the split phase for a 240volt dryer or other appliance. All other appliances that run on a single phase can and will run on either phase just wonderfully.

[LarryinID]

Originally Posted by Solo_RV_Guy

I don't know how these products are allowed to be sold, as they violate Code in most jurisdictions.

Do you have any appliance or RV system that needs 240VAC service, like a clothes dryer? If so, the kludge of adapters won't power your dryer (see bolded text).

Worrying that a GFCI will trip? Tripping GFCIs should *scare the hell out of you* because unless the GFCI itself is defective, it's tripping to protect the lives of people who use the RV.... or it's telling you that you've done something wrong with wiring.

Nah. Mine go often in the house. Reset and good to go.

GCFIs are prone to tripping.

[LarryinID]

So happy I almost never stay at places that have power, much less 50 Amp.

Alas the latest toy has 50 amp plug to run the two ACs. I can’t imagine ever needing both. I consider the rear as a spare. I’d be delighted to convert it to a fantastic fan.

Meanwhile I have a 50/30 adapter, and an adapter for the 30 amp to 110 15 amp, which is what I use most.

[freestyle_freddy]

[QUOTE=Persistent;5205625]I don't know about the adapter posted above. There is one concern. A 50 amp 240 volts system has one neutral wire for both L1 and L2 sides. That neutral is designed to carry 50 amps. With two 30 amp plugs you could have 60 amps running through that single neutral. There is no circuit breaker or fuse to protect the single neutral wire.


I'm not an electrician, but a 50 amp plug is actually 240 volts/100 amps split into two 120 volt/50 amp circuits, with one common neutral & one common ground. So it seems the neutral should be designed to handle up to 100 amps if both 50 amp circuits are maxed out.

[augerdogger]

It is amazing that our RV's survive the kludged wiring. I am an engineer not an electrician but 50y ago; a 120V 30A circuit had power, neutral, and ground; a 240V 30A circuit had 2 power and ground; a 240V 50A circuit had 2 power, a neutral, and a ground, each of the power legs was 50A, i.e. the requirement for 6 ga wire and a total of 100A. Do not bond Neutral and ground, I run a 4ga wire to a 4ft ground stake because your RV should be at the same potential as the surface you are stepping onto or you might get a shocking result. For the uninformed I had 2 RV's with 240V appliances, an A/C and a cooktop. They each had 2 invertors and 2 battery banks. The invertors were 180 degrees out of phase to produce 240V.

[jupiterjim]

That is correct if on opposing legs the 2 30 amp outlets will work

[augerdogger]

The 2 power legs are 180 degrees out of phase, so the neutral only sees 50A, not he total potential.