Split Adapters 30/30 for 50amp Service?

[Blinkies]

We have a 2023 Montana High Country 331RLS With 2 Coleman Mach Air Conditioners that I believe are 1500.
We are going to a campground that does not have 50amp service, but they tell me they have two 30amp service and suggest we get a splitter to go to our adapter. I have several questions.
1). Is this safe?
2). Will it work?
3). What do I need (besides the splitter)?
4). Can I run everything (microwave, both air conditioners, refrigerator) at the same time like I do a 50 amp plug?

Thanks for any help you can give.

[Foldbak]

Originally Posted by Blinkies

We have a 2023 Montana High Country 331RLS With 2 Coleman Mach Air Conditioners that I believe are 1500.
We are going to a campground that does not have 50amp service, but they tell me they have two 30amp service and suggest we get a splitter to go to our adapter. I have several questions.
1). Is this safe?
2). Will it work?
3). What do I need (besides the splitter)?
4). Can I run everything (microwave, both air conditioners, refrigerator) at the same time like I do a 50 amp plug?

Thanks for any help you can give.

You will be fine if the pedestal power is wired correctly and each 30 amp has its own breaker.

https://www.amazon.com/RecPro-Power-...96061113&psc=1

[NCFischers]

If both 30 amp outlets are on different hot legs then you will have 30 amps available on each leg.

[Daryles]

Use a multimeter and verify the voltages before plugging in.

[twindman]

I don't think that using a meter tells you anything. You need to know if the 2 outlets have their own breaker which means you have 2 3 amp circuits. They would all have proper voltage regardless of how they are wired.

[BB_TX]

A 50/30/30 splitter is actually all you need. Your 50 amp power cord will plug directly into the splitter.

If the two 30 amp outlets are wired to different phases then you will have 30 amp 240 vac service (don’t panic. Standard 50 amp service is also 240 vac).

If the two 30 amp outlets are both wired to the same phase, that will also work with one caveat. If both 30 amp legs were loaded to or near maximum current, you could possibly run more than 50 amps thru the neutral wire that is sized for 50 amps. That’s probably not likely to happen, but could if both A/Cs running, water heater on electric, converter running, microwave running, and a few more devices/appliances running all at the same time.

https://www.amazon.com/RecPro-Power-...96061113&psc=1

[twindman]

Originally Posted by BB_TX

A 50/30/30 splitter is actually all you need. Your 50 amp power cord will plug directly into the splitter.

If the two 30 amp outlets are both wired to the same phase, that will also work with one caveat. If both 30 amp legs were loaded to or near maximum current, you could possibly run more than 50 amps thru the neutral wire that is sized for 50 amps.

So on a standard 50A plug and service, isn't there still only 1 neutral wire and would have the same problem?

[BB_TX]

Originally Posted by twindman

So on a standard 50A plug and service, isn't there still only 1 neutral wire and would have the same problem?

First some basics. On a standard 50 amp 240/120 vac system there are two hots using a common neutral. The voltage of the hot wire referenced to neutral constantly cycles between positive 120 volts rms and negative 120 volts rms (peak voltage is actually much higher than 120, but 120 vac rms is sort of an average). Since the voltage is constantly reversing, the current is also constantly reversing. That means on the first half of each cycle the current flows from hot to neutral. On the second half of each cycle the current reverses and flows from neutral to hot.

But hot 1 and hot 2 are 180 degrees out of phase. That means when hot 1 voltage is positive with respect to neutral, hot 2 voltage is negative with respect to neutral. Since there is only one neutral wire, that would mean that current would be trying to flow both directions thru the neutral wire at the same time. But that can’t happen. The result is that only the DIFFERENCE between the two currents actually flows thru the neutral wire. The excess current is diverted thru the hot drawing the higher current. Example; if hot 1 was pulling 20 amps and hot 2 was pulling 10 amps, the neutral would only be carrying 10 amps (the difference between the two). The neutral wire can never be carrying more than 50 amps. And only then if one hot was pulling 50 amps and the other hot pulling no current. A unique aspect of this is that if both hots were each pulling the exact same amount of current then the neutral wire would be zero current!

Now, if you had the two 30 amp outlets, and both of those hots were on the same phase, then both voltages have the same positive to negative timing, and the current of the two always flows the same direction. So instead of the neutral flow being decreased by the two offset of the hots out of phase, now the neutral flow is the combined flow of both.

As stated above on a standard 50 amp system the neutral flow can never exceed 50 amps and is typically something less. And all wiring is sized for 50 amps.

But on a system using two 30 amp outlets on the same phase, if both hots were pulling 30 amps the neutral would be carrying 60 amps. The likelihood of doing that is probably low. But you can see it is possible.

I know this is a pretty drawn out description. And possibly (likely?) confusing. Something much easier explained by drawing the circuits on a blackboard.

[twindman]

BB_TX. thanks very much. An excellent explanation. I know a little electricity, but didn't understand the in and out of phase stuff. Now I see the problem.

[RMcNeal]

I have a 50/30/30 adapter we use in several campgrounds in South Carolina as several of our favorite places have dual 30amp but no 50amp service.
I have been able to run everything in our Monte including running the water heater on AC, both air conditioners, coffee maker, microwave, air fryer, etc.
No problems at all.

[Lee-CI]

BB_TX that was the most well written explanation that I've ever come across. Well done sir!
I'm an electronics tech by background, but have to play electrician as well for my job. Most folks would be shocked (no pun intended) to learn the actual peak to peak voltage of a 120vac circuit vice it's RMS equivalent read from a volt meter.

[rohrmann]

Without the long story, if you have a panel with two 30 amp outlets, a volt meter will tell you if they are on the same leg or two legs. Measure voltage across the hot legs on the two outlets. If 240 volts, they are separate legs and you are good. If you measure 0 volts, they are the same leg and that is not good.

[BB_TX]

Thanks guys. It is pretty easy to illustrate with a schematic diagram of the typical 50 amp 120/240 vac system. But I wasn't sure I could put it into words without muddying the water even more. I started out to be brief and ended up with an essay.

[bcrvman]

Originally Posted by Blinkies

We have a 2023 Montana High Country 331RLS With 2 Coleman Mach Air Conditioners that I believe are 1500.
We are going to a campground that does not have 50amp service, but they tell me they have two 30amp service and suggest we get a splitter to go to our adapter. I have several questions.
1). Is this safe?
2). Will it work?
3). What do I need (besides the splitter)?
4). Can I run everything (microwave, both air conditioners, refrigerator) at the same time like I do a 50 amp plug?

Thanks for any help you can give.

It is safe ONLY if each leg of the 30 is a different phase. It is unlikely that will be the case. I am a retired electrician and NEVER used my splitter as the posts were always wired wrong.

[Ttman]

We stay in a state park a lot and their electric only sites have hook ups that have 30 amp & 15 amp on the pole so we use this one:

https://www.amazon.com/Camco-Heavy-P.../dp/B0024E70L2

It gives us 45 amps and easily runs two 15k Dometic AC units. I run the water heater as needed on Propane. We barely use the microwave.

[GreG L.]

The splitter is all you need. A 50 amp circuit for an RV is actually two 120V 50A circuits in a single plug, 2 120V hots, a neutral and a ground, two hot legs. The splitter takes the 2 separate 120V 30A circuits and connects them to the two hots on the 50A Femail connector thus giving you two 30A legs in your RV.
As a side note there are all kinds of splitters, 20A/30A to 50A connector, 20A/20A to 30A connectors as well as the 30A/30A to 50A connector, along with some that make no sense.
You might want to get a 30A Femail to 20A mail (small converter) incase you run into a site that has 30A/20A

[RMcNeal]

Originally Posted by Ttman

We stay in a state park a lot and their electric only sites have hook ups that have 30 amp & 15 amp on the pole so we use this one:

https://www.amazon.com/Camco-Heavy-P.../dp/B0024E70L2

It gives us 45 amps and easily runs two 15k Dometic AC units. I run the water heater as needed on Propane. We barely use the microwave.

I have one of these too, but can rarely use it because if the 20 amp is a GFCI, the adapter will trip it constantly and most places we stay are using GFCI outlets on the 20 amp side.

[Bourbon County]

Originally Posted by RMcNeal

I have one of these too, but can rarely use it because if the 20 amp is a GFCI, the adapter will trip it constantly and most places we stay are using GFCI outlets on the 20 amp side.

The 15 or 20 amp receptacle on the pedestal is required by code to be GFCI protected, either by a GFCI breaker or GFCI receptacle. The receptacle is a fraction of the price of the breaker and more often used. This has been code since the late 1970s, so if you find one that isn't GFCI it was likely replaced by someone or the inspector missed it. A GFCI will by it's function will absolutely not work on a shared neutral. It measures the current on both the hot and neutral and if it senses more than 5ma difference between the 2 it assumes it is leakage and trips. In this case both outlets are sharing a neutral to the coach.

[RMcNeal]

Originally Posted by Bourbon County

The 15 or 20 amp receptacle on the pedestal is required by code to be GFCI protected, either by a GFCI breaker or GFCI receptacle. The receptacle is a fraction of the price of the breaker and more often used. This has been code since the late 1970s, so if you find one that isn't GFCI it was likely replaced by someone or the inspector missed it. A GFCI will by it's function will absolutely not work on a shared neutral. It measures the current on both the hot and neutral and if it senses more than 5ma difference between the 2 it assumes it is leakage and trips. In this case both outlets are sharing a neutral to the coach.

I'm aware. Just stating it is unlikely to work since the GFCI will trip.
IOW, don't waste your money on one.

[StageCoachDriver]

50 amp service is actually 2, 50 amp circuits, 50 amps on each leg. That's a ton more current than 2, 30 amp circuits.