50 AMP Shore power

[dp7955]

I have read several articles on this subject, some say that 50 service is 120 volt only and if it mesures any thing outher not to plug into it. Outhers say that 240 volt is only for your home. My new BC 3250 TS is 50 Amp and i am putting in 50 Amp outlet for my new unite. Good Sam had an RV triva challenge had this question?
( A 30 amp campground power outlet delivers 30 amps @ 120 VAC. What does a full 50 amp output?

• A) 60 amps @ 120 VAC
• B) 50 amps @ 240 VAC
• C) 50 amps @ 120 VAC )

They said the answer is (B), then retacted it later and said it was (C) and posted a website for reference, (In my experince (B) should be correct), timberman.com/ELECTRIC/electric.htm. (125/250V 3-Pole 4 Wire Grounding) that is commonly used for RVs, their is a link to prints that clearly shows that L1 to L2 is 240v L1 to N is 120v and L2 to N is 120v with a 14-50R plug. I just want to make sure this correct before pluging in my unite. Thanks Dave!

 

[jpmorgan37]

Dave;

Of all the 50 Amp pedestals that I have encountered, they were all two, 120 volt legs coming in. What happens when you connect your RV to this receptacle is that each leg is split to supply a separate 120 volt circuit. So in essence, you are supplying you RV with two 120 volt sources. However, if you tie them together, you do have 240 volts. Carrying this a little farther, if all you have is a 30 Amp supply, when you connect a dog leg to your 50 Amp cord, you are tying the two 120 volt legs together and that is the reason that you can only run limited appliances at the same time.

John

 

[boatdoc]

It is just as John says, TWO 120VAC legs going to the rig!! Why is this SO hard for so many to understand? It seems to pop up on RVnet once a week.

 

[ct0218]

Both John and Gary are correct, and when you calculate the total watts availabe on each you quickly see the advantage of 50A service: 30A delivers 3600 watts, 50A delivers 12,000 watts. My neighbor had an electrician put in a 50A pedestal for his new motorhome, and guess what happened? It fried everything. The electrician's insurance paid for it, and it was a hefty amount.

 

[Forrest Fetherolf]

Here is some info on RV shore power wiring..............
http://www.dasplace.net/RVWiring/wiring.html

If you run 2-50 amp feeds from the same shore power leg via 2 separate breakers.............what do you have????????

Forrest

 

[jpmorgan37]

It is the same thing when you use one of the splitters that connect a 30 Amp and 20 Amp to give you a "hypothetical" 50 Amp connection to your RV. Unfortunately, most of the time they both feed from the same leg and you fry much of the electronics and appliances in your RV. That's why most of the 20A receptacles are now Ground Fault protected and will kick out as soon as you connect. (Thank goodness)

John

 

[truknutt]

It is just as John says, TWO 120VAC legs going to the rig!! Why is this SO hard for so many to understand? It seems to pop up on RVnet once a week.

It's just the homeowner mentality---"the big plug runs the dryer & the electric stove...I know those are 240 so therefore all big plugs are 240!"

As Clark states, even a professional Electrician has a whoops cause he does stick homes all day!

 

[Triber]

50 Amp Service

Well, on my Big Horn 3670RL, 50 amp service delivers 50 amps to the 50 amp breakers. Basically, if you measure across L1 and L2, you are going to get 240V as L1 to N is 120V and L2 to N is 120. If you read across 2 X 120 V you will get 240V. The way my unit is wired, L1 feeds one 50 amp breaker and L2 feeds the other 50 amp breaker. The system only gets
120V but in essence you can draw 50 amps through each breaker for a total potential draw of 100 amps as opposed to 30 amp service which only gives you 30 amps total draw. It is much like having 2 12VDC batteries. You can wire them in parallel to get 12 V and more capacity or you can wire them in series to get 24 V. Just make sure you don't wire L1 and L2 in series or you will have 240 V and major trouble!

 

[Smokeyfl]

Residential service supplies 2 X 120V legs and a ground. A ground rod is driven into the ground and attached to the frame of the box for a frame ground. Each leg to ground is 120V. You get 240V by going across the 2 seperate 120V legs. No ground is needed for 240V. A frame ground is used for safety. A 4 wire, 50A outlet has potential for either 120V or 240V. You get a supply from each (seperate) 120V leg, a neutral and a frame ground. My rig is designed to use each 120V leg seperately (3612 Razor). Each leg has the potential for 50A for a total of 100A. A 30A set-up gives you just that, 30A total. A 30A to 50A adapter simply routes the 30A supply to both circuits - still 30A total.
In residential wiring, the neutral and the frame ground are usually bonded together.
You need a 2 pole 50A breaker. The 2 poles on the breaker will be tied together and will trip together. A split breaker designed to increase the capicity of the box will not work, as both pull from the same leg. These will not be tied together.

 

[Smokeyfl]

Should have said 2 X 120V legs and a neutral. The earth ground is supplied at the box.

 

[jpmorgan37]

There are 4 wires. Usually 1 black, 1 red, which are both 120 volt, 50 amp, 1 white neutral return and 1 ground. We have all said about the same thing and agree that for RV service you have two 120 volt, 50 amp feeds and in residential service, you have 240 volts available.