Community Forums

HHIDan · 07-20-2012, 05:53 PM

Quote:

Originally Posted by Mr_D

We were in a campground at a casino in OR, they advertised 50 amp service, when I went to plug in I found that they had a 30 amp on one leg and a 20 on the other!! Well, that does equal 50 doesn't it?
Just what inspector would approve that?

It's what you call misleading....

Cobra1 · 07-20-2012, 07:05 PM

Ok, for a typical rv all of the connections, 50 or 35 amp is a 120v circuit. The 50 is just 15 more available amps than the 35.

Anyway, when discussing different voltages and amps, to be clear you must convert everything into watts (amps x volts). For example a 240v 50amp circuit has 12000 available watts (240 x 50). The same circuit can be used as 2 120v circuits at 50 amps each but when you do the math for watts it comes out to the same 12000 available watts. (120 x 50) plus (120 x 50) Convert everything to watts and all will make sense. That is why all generators are rated in watts. Hope this helps.......

bdickson · 07-20-2012, 08:45 PM

Quote:

Originally Posted by Mr_D

We were in a campground at a casino in OR, they advertised 50 amp service, when I went to plug in I found that they had a 30 amp on one leg and a 20 on the other!! Well, that does equal 50 doesn't it?
Just what inspector would approve that?

In a properly wired 50 amp outlet, there should be 240 volts between the two hot legs. I made up a tester which is a dual outlet box, with one leg of the supply connected to each outlet. I plug a tester into each one to verify that I have 120 volts and no polarity reversals, bad grounds etc. On the side of the box is a 240 volt neon light tester which is wired across the hot legs. If it lights up then I know its a properly wired 50 amp supply and not a "cheater" that MR_D describes. I'll try to post a picture of the tester. I made it for about $40 worth of parts from Home Depot.

azpete · 07-23-2012, 09:25 AM

in theory, 50 amps is 50 amps on each leg. 100 amps total.
but in reality, in a campground setting, it all depends on how many people are connected to that particular power supply.
at many rallies, and older campgrounds, you will be lucky to get half the advertised power rate. 20 or 30 coachs hooked to the same line can greatly reduce the amperage available. as a vendor at quartzite, i was lucky to keep my batteries charged, much less run anything. yes, vendors get power with their campsite.
you should always have a way to check your power supply, if you are having problems. low voltage can ruin lots of appliances.
a man's got to be aware of his limitations. (dirty harry)

HHIDan · 07-23-2012, 09:45 AM

This is my 50 to 30 amp adapter. Technically it's a 30 amp adapter if I plug the two 15 amp plugs in a "split outlet". If I use a regular outlet then it's a 50 to 15 amp adapter.
When I use a split plug, my panel thinks I'm hooked up to 50...

I only use this adapter at home in the garage. Outside the garage I have a regular campground style 50 amp. outlet.

Lug_Nut · 07-23-2012, 12:18 PM

Some campgrounds run two 50 amp 120 VAC parallel, or in the same phase. This will supply two separate 120vac 50 amp services. Being in the same phase, do not support 240VAC. Jellystone park in Frankinmuth had a section of their 50 amp offering like this. They are the only camp that I have run into with this below standard set up. The only way I knew was my dryer would not operate which is only a 240 appliance.
To be fair, I have not stayed in this section for several years, so perhaps they have upgraded it by now.

Peter

Mr_D · 07-23-2012, 12:31 PM

Quote:

Originally Posted by bdickson

In a properly wired 50 amp outlet, there should be 240 volts between the two hot legs. I made up a tester which is a dual outlet box, with one leg of the supply connected to each outlet. I plug a tester into each one to verify that I have 120 volts and no polarity reversals, bad grounds etc. On the side of the box is a 240 volt neon light tester which is wired across the hot legs. If it lights up then I know its a properly wired 50 amp supply and not a "cheater" that MR_D describes. I'll try to post a picture of the tester. I made it for about $40 worth of parts from Home Depot.

Since there was 120 volts on each leg I don't know if any tester would find the different amp ratings on the pole. You'd have to load test it to find anything.

alvinc · 07-23-2012, 12:34 PM

Is there a specification somewhere that states the configuration of a RV power cord and pedestal supply? Does it state 2 x 120VAC at 50amps with a common neutral, or does it state a 240 VAC at 50 amps with a 120VAC neutral?

The difference is that the neutral in the second case will need to carry no more than 50 amps, the first case might require the neutral to carry 100 amps. Since all of the 50 amp RV cords that I have seen all use the same gauge wire for all 4 conductors, this means any of the pedestals without 240 VAC across the hot wires are dangerous and illegal.

RustyJC · 07-23-2012, 12:45 PM

Quote:

Originally Posted by alvinc

Is there a specification somewhere that states the configuration of a RV power cord and pedestal supply? Does it state 2 x 120VAC at 50amps with a common neutral, or does it state a 240 VAC at 50 amps with a 120VAC neutral?

Many (most?) 50 amp RVs have a sticker that specifies 120/240 VAC 50 amp service. This is 120 Line to Neutral and 240 Line to Line.

Rusty