50 amp service - help - Page 4

AKO · 08-02-2006, 05:13 PM

Rusty, Bob & adj, Are you guys really disagreeing, or just describing the same thing with different words? Maybe we could think of it as THREE waveforms! And no I do not mean "three phrase" power.
The transformer provides 240 volts across V1 - V2. This is single phase (one wave form) at 60hz and maximum amplitudes yielding +240...-240 Volts (these are nominal numbers; the actual almost always being lower). No other wires are required to come to your distribution panel. If all our lights and appliances were built for 240V, we would be done.
However by providing a third wire coming from the center grounded tap of the transformer coil we can have 120V (maybe safer and less expensive light bulbs?? I don't really know why). Anyway, we now have two 120V circuits available(V1 - N, V2 - N).
Each is single phase (one wave form) at 60hz and amplitudes yielding +120...-120 Volts. IF you were to plot these two waves (amplitude along the Y-axis, time along the X-axis), on the same graph, then you would indeed see that they are shifted one half cycle (180deg) from one another.
This happy happenstance saves the expense of requiring yet another (the fourth) wire "returning" to the transformer, or the center tap wire needing to be larger than the "hot" wires.

So, I think everyone is right on!! Peace and love to us all.

MikeT · 08-02-2006, 07:18 PM

AKO

Is that a WYE or Delta configuration??

AKO · 08-03-2006, 12:01 AM

Gee Mike... How would I know? I went to public school.
I think wye has to do with British underwear, and the delta is where we go to git them gators and crawdads (good eatin both).
Just know that 120 gives a nice tingle, at 240 one has to consider if it is worth going all the way back to the breaker box to turn it off, and feeling 480 makes me go oooooo. Any thing more than that I will leave to you guys.
Peace and love to us all!

RV Wizard · 08-03-2006, 12:38 AM

Guys, I look at phasing this way. A phase is 360 degrees. From 0 volts to a peak of a positive voltage is 90 degrees and then back to o volts is another 90 degress; from ther to a peak negative voltage is 90 degrees and back to 0 voltage is another 90 degrees. At anytime you measure from peak to peak on a single phase you have maximum voltage. As you throw a tap into the mix you now have another point from which to measure a peak voltage point from and can measure positive or negative with alternating current. Some concider positive voltages are out of phase of negative and; the electrons are flowing in two different directions at this instant. You migh say they are out of phase in a single phase circuit. I hope this has not muddied the waters too badly. We will see.

rebelsbeach · 08-03-2006, 04:03 AM

Round and round we go, where we stop nobody knows...

You guys will one day have to "agree to disagree" or maybe start talking about Walmart!!

Bob Hatch · 08-03-2006, 04:48 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by rebelsbeach:
Round and round we go, where we stop nobody knows...

You guys will one day have to "agree to disagree" or maybe start talking about Walmart!!

</div></BLOCKQUOTE>

NOT WALMART!

OK, I will be one of the first to agree that the electric threads get pretty long, and sometimes stray into the technical end, but, in my opinion, they are important.

I believe it is vital that folks with a 50 amp rig understand that they are, in fact, dealing with 120/240 volt electric service, and not some variation thereof. Again, in my opinion, this can be a life threatening situation if the person thinks that it is not what it is.

There are too many folks out there that know just enough about electric wiring to be dangerous, and if they think that they only have 120 volt service on a 50 amp rig, they can make some pretty big mistakes, with really big consequences.

So, while they might be boring, or a PITA, about the only thing that makes sense is to let them run to conclusion. Just my opinion.

rebelsbeach · 08-03-2006, 05:11 AM

OK Bob....With this thread having lost it's Winnebago connection some pages ago I am, at the very least going to remove the cross-link to Winnebago....I had simply figured that seven pages of discussing the how and why of 50A was sufficient...
As long as there seems to be a factual exchange of the facts concerning the issue I have no problem with it continuing, I am just leery that this thing will soon erupt into an "I know more than you and you're dumb" type of diatribe, which at that point we'd kabosh...

I dearly LOVE the chance for positive debate and the exchage of factual possibilities regarding an issue....it is only at such time that the issue seems to have been exhausted that I look to end the topic.

At your urging I will graciously step aside and allow the sparks to connect....

Thank you for your continued support of what I consider the premier location for RV information on the internet, I sincerely appreciate your efforts.

Bob Hatch · 08-03-2006, 05:16 AM

Thanks, I thing removing the cross link is a good idea, but letting the exchange continue allows folks with an interest to learn, and learning never hurt anyone.

RustyJC · 08-03-2006, 05:19 AM

As Bob says, an understanding of 120/240VAC 50A service is vitally important. If a shore power pedestal is cobbled up to feed both 50A legs off the same phase, then (since only a very few top line RVs use 240VAC appliances) everything within the rig will still function correctly with 0VAC instead of 240VAC across the 2 each hot legs, but the neutral leg of the shore power cord, which is not protected against overcurrent by a breaker, could easily be overloaded and melt down. It's a silent risk that RVers need to understand and be aware of.

If I didn't believe this subject was that important, be assured that I wouldn't waste my time on it.

Rusty

Bob Hatch · 08-03-2006, 05:35 AM

Rusty, there's that, and other problems as well.

Lets play a little imagination game. A guy with a 50 amp rig wants to install a stacked washer and dryer. He wants to run the washer and dryer at the same time, and realizes he will need 2 receptacle's for this purpose. He looks at his distribution panel, and it's full, but he knows that he can tap any one, or more, or the existing breakers with an additional line. and after some thought decides that the best thing to do is run a line from each of the AC breakers to the new receptacle for the W/D setup. He then decides that it really doesn't make a lot of sense to put in 2 full, dual 120 volt receptacles when one will do, so he breaks the contact on a single receptacle. He can now feed the top one with one line, the bottom with another, and can run the washer, and dryer at the same time, as long as he doesn't run the AC's. Cool, and it can't be dangerous because he read on the web that RV service isn't 240 volt, it's really 2, 120 volt lines.

So now he has 240 volts of power, in the same small junction box, fed from untied breakers. Dangerous, and foolish, and based on false information he picked up on the internet.

Sunny · 08-03-2006, 09:36 AM

Rusty
What you are saying can happen in more places than just in the RV. We stayed in an RV park (many years ago before 50 amp was hear of) they had pedestal at the end of each row with 2 - 100 amp breakers, one breaker feed every other site in the row. They had a rally come in all at one time about 50 to 75 rigs everyone turns on tha AC. And guest what the neutral at the end of 2 of the rows burnt off where the 100 amp breakers were. This being said I think both feeds were the same phase with the neutral trying to carry 200 amp.
I hope this makes sense.

Tom
PS maybe we should get into 208 Volt.

RustyJC · 08-03-2006, 10:01 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Sunny:
PS maybe we should get into 208 Volt. </div></BLOCKQUOTE>
Tom,

Only if you agree to explain the "wild leg" concept.

Rusty

Sunny · 08-03-2006, 11:48 AM

Rusty
let"s see is that on a /\ or a Y.
The one with 151 Volts.

No way.

Tom
PS: How do I underline???????

ruppr · 08-03-2006, 04:38 PM

Let's talk about the 'high leg' possibilities and really open things up for total confusion!

Best,

Bob Hatch · 08-03-2006, 08:16 PM

So, after 8 pages and lots and lots of information, this question was posted today on the irv2.com RV Forum:

"can anyone tell me how to wire a 50 amp service at the main power panel? do i use two single pole 50 amp breakers. I asume that they work off the same 120 volt bar? My motorhome's set up with a 50 amp plug with 3 blade's and 1 bare copper gnd. should be 120v + 120v + common + gnd. If i used a regular 50 amp breaker that would give me 240v. right? don't want that. thx. ahead of time. Lee"

50 amp question

What say you Rusty?

Route 66 · 08-04-2006, 01:54 AM

I guess some folks just don't understand electricty, and that's OK.

Not to hijack the thread, but this reminds me of a saying.

"There are only 10 kinds of people that understand binary, those that do, and those that do not."

mrschwarz · 08-04-2006, 02:18 AM

This reminds me of when I bought my first motorhome. I asked questions about the 50 amp connection and the salesman told me that an RV connection was different. He told me that each leg needed to be connected to the same side in the 240 volt panel because all of the appliances were 110 volt.

I thought about it for a minute and asked him, 'Wouldn't that mean under a full load that 100 amps (50 + 50) would be passing through the neutral?'

He then replied that maybe he doesn't know enough about electricity to answer. I have no idea how many other people he gave this same advice to.

While it's good to understand RV systems, it's also good to have little common sense about electricity and wiring.

RustyJC · 08-04-2006, 03:27 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Bob Hatch:
What say you Rusty?

</div></BLOCKQUOTE>Bob,

My momma didn't raise no fool!

I've had enough of this to last me for awhile.

Rusty

adj · 08-04-2006, 04:53 AM

I aplogize to the viewers of this thread. I feel as though I have used it for a private discussion on AC theory. And, although it is relevant, it isn't necessary to answer the original basic question.

Norm Newhall · 08-07-2006, 03:28 PM

Thanks to all who answered this (or tried to)!

Best to just call it information overload. Now I at least know some of the things to watch for!!

The new 50 Surge Guard is sitting here in the den, waithing to be installed in the new rig.........

Again - thanks.