15/30/50 SHORE POWER PLUG IN ?

I obtained a 50 to 30 dogbone which plugs directly into the male plug on the back of my camper. I rarely need to run both AC units, and this allows me to use a much, much, smaller 30 amp extension cord to serve the camper when we are traveling. Horsing that huge 50 amp cord around was a real hassle. Again, the 30 amp breaker on the campground box protects me.

Bob the best thing for you to do is search for a schematic drawing of a 50 amp to thirty amp adapter.

The fifty amp plug will only have one hot wire running to the 30 amp socket. There are three wires in the adapter, one black hot, one white neutral and one green ground. You will not see them but the schematic will show you how they run.

When you plug into a 50 amp panel using an adapter the is no chance you will get more than 50 amp potential and the breaker in your distribution panel will limit your rig from using more than 30 amps.

It will be safe.

KMLsquared wrote:
Man I feel sorry for the op. This thread is like watching the news on tv, confusing and contradictory. Some of the responses are wrong and add to the confusion. It’s really no wonder this forum is dying. Yes 50 amp is 240 phase to phase and 120 phase to neutral. There, one more response that the op has no idea what is right.

Yes, there is some misinformation in this thread but you need to know that when it comes to 120/240 volt services, it is incorrect to refer to "phase" and doesn't help the OP. In the electrical industry, the correct terminology is line 1 & line 2 and line to neutral. "Phase" is terminology used in 3-phase power systems.

Man I feel sorry for the op. This thread is like watching the news on tv, confusing and contradictory. Some of the responses are wrong and add to the confusion. It’s really no wonder this forum is dying. Yes 50 amp is 240 phase to phase and 120 phase to neutral. There, one more response that the op has no idea what is right.

In Missouri at a Campground we sat up and connected 50 amp to ems. Went in and turned on the lights ACs were already on. Immediately notice the lights wer real dim with one side dimmer than the others and the Acs not wanting to run immediately hit the generator went to tower and disconnected. Figured everything was fried but was running fine on generator. Got hold of the handyman and he called boss. The ems plug in was hot. Told him what happened and he insisted everything on his end was fine at first. We moved to a different site and everything was fine. he gave me every kind of story you can think of what was wrong. never did find out but I figured one hot lead must have wired to the other. Others have said the 50 amp is two 50 amp and a common ground. I cannot see how to add up to 120 volt 50 amps to get 240 volts.

In Missouri at a Campground we sat up and connected 50 amp to ems. Went in and turned on the lights ACs were already on. Immediately notice the lights wer real dim with one side dimmer than the others and the Acs not wanting to run immediately hit the generator went to tower and disconnected. Figured everything was fried but was running fine on generator. Got hold of the handyman and he called boss. The ems plug in was hot. Told him what happened and he insisted everything on his end was fine at first. We moved to a different site and everything was fine. he gave me every kind of story you can think of what was wrong. never did find out but I figured one hot lead must have wired to the other. Others have said the 50 amp is two 50 amp and a common ground. I cannot see how to add up to 120 volt 50 amps to get 240 volts. I manufactured wire but didn't do any wiring.

fj12ryder wrote:
So if someone wired up an RV outlet the same as a welder outlet, and plugged a 50 amp RV plug into it, what would happen? Nothing?

I know I've read about people plugging into an outlet at someone's house and frying their electrics due to running 240 Volts to their 120 appliances. Would that just be a result of the outlet being wired incorrectly, and have nothing to do with the wirer copying a welder outlet?

Am I laboring under a misapprehension here? I know that I lost one leg of my 50 amp service and then had some appliances, lights, and outlets not work.

Plugging a 50A RV into a 240V welder plug is just a problematic as plugging a 30A RV into one. It's also the same as if you have an open neutral due to a poor connection to a legitimate 120/240 RV pedestal.

What happens is all of the 120V loads on one leg in your RV are now effectively wired in series with all of the loads on the other leg. If both legs drew the same amount of power, they would stay at 120V each. However the reality is that the heavier loads will pull their floating neutral up toward their leg which makes their voltage much lower than 120V and the opposite leg rises by the same amount to something higher than 120V. Worst case you can approach nearly 0V on one side and 240V on the other. This is why an EMS should be used on 50A RV's in my opinion.

Some reading here: https://www.electriciantalk.com/f2/theory-open-neutral-36386/

fj12ryder wrote:
So if someone wired up an RV outlet the same as a welder outlet, and plugged a 50 amp RV plug into it, what would happen? Nothing?

I know I've read about people plugging into an outlet at someone's house and frying their electrics due to running 240 Volts to their 120 appliances. Would that just be a result of the outlet being wired incorrectly, and have nothing to do with the wirer copying a welder outlet?

Am I laboring under a misapprehension here? I know that I lost one leg of my 50 amp service and then had some appliances, lights, and outlets not work.

Welder is usually 6-50 outlet and the 14-50 plug will not fit. There is only one way to wire a 14-50 outlet or plug to meet code and no harm will come no matter where it is located. Nothing special about an RV park or at home. Same, same.

Unfortunately the NEMA TT-30 (120v RV) and the older but very common NEMA 10-30 (240v) dryer outlet look similar. People seem to force the mismatched plug in on a weekly basis and burn up half the items.

So if someone wired up an RV outlet the same as a welder outlet, and plugged a 50 amp RV plug into it, what would happen? Nothing?

I know I've read about people plugging into an outlet at someone's house and frying their electrics due to running 240 Volts to their 120 appliances. Would that just be a result of the outlet being wired incorrectly, and have nothing to do with the wirer copying a welder outlet?

Am I laboring under a misapprehension here? I know that I lost one leg of my 50 amp service and then had some appliances, lights, and outlets not work.

Alan_Hepburn wrote:

fj12ryder wrote:

But I do wonder about people that say they have plugged into a welder outlet and damaged their RV. Or is that just a case of the outlet wired incorrectly for the welder?

Those people are usually dealing with a 30A RV - some older 240V 3 terminal outlets are close enough to an RV 30A outlet that some people will force their plug into the outlet, with the expected results.

An RV 30 amp plug will not fit into a 3 terminal 240 volt welding or older style dryer or stove outlet. The 30 amp RV plug has two blades and a pin, while the 240 volt outlet has three blade sockets. That third blade socket is narrower than the ground pin on the RV plug. To make the RV plug fit into that 240 volt 3 blade outlet you either need to modify the pin on the RV plug or use a hammer to force it in.
The most likely way anyone has ever damaged their RV is to have either replaced the welder's outlet with a 30 amp RV outlet, thus incorrectly wiring it, or they replaced the plug on the RV with a welding machine plug, again it would be miss wired.
That welding outlet has no neutral, so wiring a 30 amp RV outlet to it would mean there was a hot circuit wired to the neutral blade of the RV outlet. Similarly, wiring a welding machine plug to your 30 amp cord would mean one of those hot circuits of the welding outlet would now be connected to the neutral wire of the RV cord.