50 Amp Service That Is Only 30 Amp

[snybe]

I was wondering if while hooked up to 50 Amp service and my 2011 Fleetwood Discovery 40G reads 30 Amps, if it will hurt anything or just limit what all I can run in the coach?

I checked the 50 amp plug at the box which is a standard 4 post (X,Y,W, &G) plug, but it looks like the electrician wired it with 120 coming off of either L1 or L2 but not both because I see zero (0) volts across X and Y with my voltmeter. I see 120 Volts between X and W and Y and W and X and G and Y and G and zero (0) between W and G.

Since it looks like the 120 is coming from the same side, which means the phases will not be balanced, is that a fire hazard on the coach side or the park's side?

Also I would be curious as to why someone would wire a 50 Amp service in this manner? Does it save money somehow? I checked the feeds coming into the bottom of the power box and there are 4 wires coming in and 4 going out, so they did not jump the poles in RV service box, which must mean they did it at the main circuit box.

Thanks!

[rossboyer]

If you have 50 amp load on one leg in your motorhome and 50 amp load on the other leg, the neutral wire will be trying to carry 100 amp load which is a major hazard for you. Also, I doubt that the campground has wired the neutral with #2 wire; therefore, the potential of having major neutral overheating in your coach and in the campground wiring is very great. I would ask to be moved to a site that is wired correctly.

[wolfe10]

While Mr Boyer is correct, IF, repeat IF you limit your total power needs to 50 amps (half of what is available on a properly wired 50 amp circuit where you have TWO 50 amp hots) you should not have a problem with overloading the neutral.

As you know on a properly wired 50 amp circuit, the neutral carries only the DIFFERENCE between loads on L1 and L2.

With both hots on the same leg, the neutral now carries the SUM of the loads.

As to why-- other than ignorance, the only reason I can think of is that the park was wired for only 15/20 and 30 amp (i.e. they only pulled ONE HOT) and they wanted to "upgrade".

Brett

[snybe]

Brett and Mr. Boyer,

Thanks for the info.

This morning the park electrician stopped by and when looking at the main electrical panel, they had the 120s coming off of L1. After switching them and making sure one of from L1 and the other is from L2, we now have a true 50 amp circuit.

Thanks again!

Don

[rossboyer]

Thank you letting us know the solution.

[Rjroxie]

I can tell you from experience that if you are going to be staying places that you are not familiar with then you need to get a meter, learn how to use it, and check the plug before you plug your coach into it. The one time that I failed to check the plug, it cost more that $2000.00 and that was looking for deals and doing all of the work myself.

Microwave, inverter - charger, electric side of refrigerator, back tv, power supply for satelite, satelite receiver.

Now with some upgrades like the hardwired progressive surge protector, I still put my meter on the plug before I plug up.

We tend to get comfortable doing the same thing over and over and never seeing a problem, then when you don't check, you can have a problem.

[QuiGonJohn]

Rjroxie, good point. I have a 30 amp RV and in the reverse of the OP's issue, it may be just as conceivable that a park that has 50 amp/220v on a post, might wire in a 30 Amp receptacle, but mistakenly apply 220v across that vs. 120v. And that would fry my RV. I hadn't thought of this, but I will start checking voltage, I already carry a meter.

[Rjroxie]

Rjroxie, good point. I have a 30 amp RV and in the reverse of the OP's issue, it may be just as conceivable that a park that has 50 amp/220v on a post, might wire in a 30 Amp receptacle, but mistakenly apply 220v across that vs. 120v. And that would fry my RV. I hadn't thought of this, but I will start checking voltage, I already carry a meter.

That is exactly what we did, our coach has a 50amp service and I used the 30 to 50 amp adapter so we could plug into the 30amp plug that my brother in law had wired up for us, at their hunting camp, it was wired up like an old 220 dryer plug, and it fried everything listed above, we were so excited to see all of our family members and talking and for that split second it never crossed my mind to get the meter out of the coach and check the plug. Lesson learned and upgrades made.

Hope others can learn from my mistake.

[QuiGonJohn]

I put in a 30 Amp plug at my house, so I could plug the RV in on the side of the house. I too came off the dryer circuit, but I was smart enough to only draw the power from one side of the circuit, 120v. Then I used 10 gauge wire for the 2 foot run through the wall and to the outlet. If we put the A/C on in the RV, we put a danger tag on the dryer to shut off the A/C before using the dryer.

[wolfe10]

To make it clear:

30 amp RV= ONE hot, one neutral, one ground= 30 amp max available

50 amp RV= TWO hots (50 amp L1 plus 50 amp L2), one neutral, one ground= 100 amps max available.

Yes, it is common for a household dryer to have TWO HOTS (AND SOMETIMES NO NEUTRAL in older homes). Plugging into that give you a HOT on what should be your hot AND puts another hot on what should be your neutral. Lots of damage. NEVER PLUG INTO A HOUSE CONNECTION THAT LOOKS LIKE A 30 AMP OUTLET WITHOUT TESTING IT.

[QuiGonJohn]

So, as I mentioned, I put in a 30A receptacle using a TT30R on the side of my house, for my RV. I knew when I put it in that it only had 120VAC across it, and tested at that time. But I just tested it again with my voltmeter. Across the 2 angled slots, it is 122.8VAC. Now here is where I ask to please pardon my stupidity, but I have read a lot about polarity, as well. First off, I never really thought AC had to worry about polarity, since it alternates between pos & neg at about 60 cycles. But, is there a way to test, with a standard voltmeter if this plug is wired in correct polarity. When I installed it, I followed all the white/black/green wiring instructions and got that from the same corresponding source power.

[wolfe10]

http://www.myrv.us/electric/

Click on 30 amp service.

[QuiGonJohn]

Thanks, on the outlet testing screen on that website, those are the exact tests I did for my outlet and I got those same results, so I am good.

I was a little worried, until I read that, as I also got the 120VAC from the hot to ground. But I see that is correct.

[Lenpa]

I just ran into the same thing the original poster did. Parked at site #94 at the Dewayne Hayes Corps of Engineers campground near Columbus, MS. Appeared only the one site (just my luck) that was wired incorrectly. Park personnel were notified.

In my case I was not aware there was a problem until standing near the refrigerator (outside) I heard it ignite. I thought now why is it running on gas when I have 50 amp service? Figuring it had been switched manually I came inside and discovered it was on AUTO. Further checking revealed the load share panel indicated only 30 amps.

I use a 50 amp Surge Guard (portable) and it had not registered any problems. Time to get the meter out. Sure enough, reading across the two hot legs showed a big ZERO. The Surge Guard was doing it's job and assumed I was on a 30 amp outlet and using a dog bone.

I did not get excited about neutral getting overloaded because the load management system does an excellent job of keeping the total draw below 30 amps. Without the load management, I would hate to think what might have happened. Hopefully the park will get this site fixed ASAP.

Lenp