100 amp service?? Someone educate me

[rohrmann]

If on a 120/240 volt circuit, there is say 10 amps neutral current from one leg and say 8 amps neutral current from the other leg, you just subtract the difference, and there is only 2 amps current on the neutral. That is the reason the neutral is allowed to be half the size of the hot legs in many circuits. Yes, the current flows in opposite directions in the neutral, but the flows cancel each other out, so the amperage in the neutral is much less than the hot legs.

[snfexpress]

We have stayed at CG's with 100 amp 240 volt service for the larger Class A's that require it. Usually just one or two spots if available.

[jlb27537]

The advertized 100 A service is just that. 2 50A plugs. Some Prevost type units have 2 50A power cords. Voyager RV Park in Tuscon has several 100A sites as does Skyline RV Ranch in Bandera, Tx.

Stayed at both.

Yes you would need 200A service to feed them. However 30A per leg is usually all is really required.

I did maintenance in both parks.

Jim

[Phil P]

quote:Originally posted by BB_TX

Again I will have to disagree, although it may just be semantics.

You can have 50 amps flowing thru line 1. And at the same time you can have 50 amps flowing thru line 2. So at maximum current flow thru both lines at the same time you can have 12,000 watts of power (100 amps x 120 volts = 12,000 watts).

You can't have more than 50 amps flowing thru either hot leg or any wire at any time. And (at any given time) the current flowing into one leg is flowing out the other leg. So in that respect it is not additive. But you do still get the EFFECT of having a total of 100 amps IF you have loads that would draw the maximum of 50 amps from each hot leg at the same time. The 50 amp breaker is a double pole breaker, each pole rated for 50 amps. Since the hot legs are not additive, you can have up to, but not more than, 50 amps flowing thru each pole and to each separate group of loads simultaneously.

Look at the drawing.

As you pointed out it is AC so one second one end on the transformer is + and the other end is -. The next second that changes. So the current flows thru both breakers at the same time in the same direction.

The power flows between the 2 lines. If you exceed 50 amps anywhere in the circuit you will trip the breaker.

We haven’t been talking wattage at all and if you want to go there then you need also to talk about power factor.

All of the information I have posted came from the text books I just made a typo error. It is a common mistake and I thank you for pointing that out. It is a long course if you study only the AC electrical part 8 hours a day the course takes 2 weeks to finish. It has now been 8 years since I did the last refresher course.

The school I attended for the 2 week course in Tucson had a demonstration panel with amp meters installed in all three lines and as the load was equalized on Line 1 and Line 2 the neutral amperage dropped accordingly until it was no longer readable by the meters being used. The voltage meters wired to neutral remained at 120 volts and the volt meter wired between line 1 and line 2 remained at 240 volts thru the entire demonstration.

The power flows between line 1 and line 2 when the load is equal. The difference between line 1 and line 2 is carried by the neutral.

If this were not the case the neutral wire would have twice the capacity of the wires to line 1 and line 2.

So we play the game with math.

100 amps X 120 volts = 12000 watts

50 amps X 240 volts = 12000 watts

This is simple formula that doesn’t take into account power factor.

Phil P

[BB_TX]

As I said, semantics. We have said the same thing in different words and ways. As an electrical engineer and 30 years as a control system design engineer I have been there also.

[BB_TX]

Sorry that this got off the original topic. But good to see that there are some good answers as to the meaning of 100 amp service at an RV park.

[ols1932]

In reality, when RV parks say they have 50 amp service there are two 50-amp legs on the line providing 100 amps. With the two 50-amp legs they can hook on to one leg for the RV and still have the other 50-amp leg available. This allows them to legitimately say they can provide 100-amps.

Orv

[K0LCB]

If I remember my basic elect. Theory, and that was a long time ago, I X E = W, applies to a D.C circuit, A.A. Requires you to figure root means squared or something like that.

[BB_TX]

quote:Originally posted by K0LCB

If I remember my basic elect. Theory, and that was a long time ago, I X E = W, applies to a D.C circuit, A.A. Requires you to figure root means squared or something like that.

Volts times amps equals watts, in a purely resistive circuit. When you get into circuits with inductive loads (such as motors) and capacitive loads then a thing called power factor comes into play. It affects the realized power available from the same voltage.

Root mean square is the method of specifying voltage in an AC circuit. What we know as 120 vac actually has a peak voltage of approximately 169 volts at the high point (and negative 169 at the low point) of the voltage curve. But after doing root mean square calculations it comes out to 120 volts. Since the voltage passes thru zero volts twice each cycle you don't get the full benefit of the 169 volt peaks.

[K0LCB]

Thanks Bill! It's been many moons since 1964

[richfaa]

BB TEx,, I remember that but I forgot it 10 mins after I retired. I was however a electronic technician not a electrician and there is a big difference. Folks always thought I could do electrical work and I would say no if you have radar that needs repaired I am your guy otherwise call a electrician.

[BB_TX]

Yeah, I still have nightmares about it sometimes from my school days oh so many years ago. Even the description above is highly simplified.

[catskiner]

Some of the newer class A MH are all electric,no propane at all.

[Phil P]

quote:Originally posted by catskiner

Some of the newer class A MH are all electric,no propane at all.

The last RV show we went to some of the bigger 5th wheels were equipped with AC refrigerators and 4 large batteries to power an inverter.

The excuse used was a high failure rate for the larger gas refrigerators.

Phil P

[Papafish]

Hi all. Ok, just to double check so I don't zap my Monty with 220v, if I want a 50 amp 120 volt shore receptical I would use a 220 v double wide breaker and wire one leg to line 1, one leg to line 2, neutral and ground. Correct? Thanks for the help, Steve
Also, why when I make a post does it show up twice?

[Papafish]

Hi all. Ok, just to double check so I don't zap my Monty with 220v, if I want a 50 amp 120 volt shore receptical I would use a 220 v double wide breaker and wire one leg to line 1, one leg to line 2, neutral and ground. Correct? Thanks for the help, Steve
Also, why when I make a post does it show up twice?

[Phil P]

Hi

I have had the double post happen several times. You have a delete button at the top of your post I just delete the second one.

You have the idea on how to wire the 50 amp service for the Montana if you are coming from the breaker box if you are coming from a different receptacle like a range receptacle (3 wire) one of the wires will have to be run out side of the receptacle I don’t remember if this is the ground or the neutral so be careful.

Phil P

[BB_TX]

You have the right idea on the wiring. Same as your house wiring. Here is a good source for wiring information.

Sometimes if things are running slow there is a tendency to click Post New Reply twice thinking the first time did not take. The result will be double posts. As Phil stated, just click on the delete button for the second one.

Also since your question was not really directly related to the original question in this discussion, I would suggest you start a new post next time you have a new question to get better results.

[jlb27537]

100A service in a RV park means there is 2 50A plugs in the box.

That would be a 50A plug which we all know is 50A on 2 legs of 240ac.

Your larger stuff like Prevost, which are total electric, have 2 50A power cords.

We worked one winter in Tuscon (Voyager) that had a section that they used for the Jewels, 1M priced rigs, and the park we go to in Bandera, Tx has some 100A sites. (Skyline Ranch)

Jim

[paulinbaja]

We certainly beat the theory to death! It was fun reading the different way people attempt to explain the same thing. One comment that was wrong along the way indicated the neutral can be 1/2 the size of the power legs. This is incorrect, it is the same size in a typical panel wiring. It does not have to be double the size due to the sign wave reversing the polarity! All that has to do with resistive loads, now with 3 phase digital power supplies all that gets adjusted due to the nature of digital power supplies and the way manage power! It is lots of fun!