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Bus Discussion => Bus Topics ( click here for quick start! ) => Topic started by: pawagan on February 09, 2007, 12:54:07 PM
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When you have a 50 amp plug in, how much is the voltage coming into the coach?
The reason I am asking the question, is due to a friend's request to have a 50 amp service installed at his summer home, so he can hook his RV to service.
I wasn't aware that you could have anything but 220 volts if you had a 50 amp service to plug into.
I dont recall reading anything about this in the magazine.
Please let me hear from someone.
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I don't understand all the electric things, however I do know with a 50 AMP plug you only get 110 in the coach. Mine has a 50 AMP plug. When I got it I wired my own 50 AMP circuit in the garge so I could plug in. Yoy will get more knowledable people who will reply but that is what I did.
ED
MCI 7
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50 amp is essentally 240v with two legs of 120v center tapped with the nuetral. That gives you two 120v 50 amp legs.
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Jerry is essentially correct here. A 50 amp power outlet is 240 volts. It is composed of 4 wires: 2 hots, 1 neutral, and one ground. The two hots are 120 volts each in reference to neutral, but out of phase with each other. These two hots are typically used for 240 volt applications in a household environment.
However, in a coach, there is generally no 240 volt equipment. Often, one leg of the connection is used to power the entire coach, but it is not uncommon to use both, since most coaches use a standard house breaker box, which is composed of the same 4 buses. But the usage is typically all 120 volts, or one of the hot legs paired with the neutral.
Your buddy is correct in wanting to install a 50 amp, 240 volt outlet to plug into. He should use a standard RV power pole, with the standard 4 prong receptacle.
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I don't understand all the electric things, however I do know with a 50 AMP plug you only get 110 in the coach. Mine has a 50 AMP plug. When I got it I wired my own 50 AMP circuit in the garge so I could plug in. Yoy will get more knowledable people who will reply but that is what I did.
ED
MCI 7
The statement above is incorrect. The correct terminology is 50 amp, 240/120 volt service. There are two legs of 120 volts at 50 amps available for a total of 100 amps, or one leg of 50 amps at 240 volts available, or any combination of the two, as long as you do not exceed 50 amps per leg.
You could operate an electric range that requires 20 amps at 240 volts and any combination of other electrical devices that require not more than a total of 60 amps at 120 volts. This 60 amps would have to be split at 30 amps each for each leg.
Richard
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I have my bus wired straight 120v. I do have a 50 amp plug, but only use one side of the plug. I have read many a post where campers have plugged into an improperly wired 50 amp plug and gotton a full jolt of 240v into the coach. If you have doubts as to the wiring of the plug, have a volt meter with you. Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC
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Tom is right on with the manner to check the wiring on the campsite side of the receptacle. If that is incorrect, you may have higher voltages within your coach here they should not be.. That is 240 on a 120 plug within the coach.
To further the point, Coaches like homes will have two incoming 120 legs (circuits) which get distributed thru out. If you only wire to one side it provides you protection, but you limit your 50 Amp plug to essentially 25 amps. 50 amp service is 25 amps per leg, Two legs coming in, each 120 VAC.
If you can live with utilizing only one side of the 50 Amp 240VAC plug in, and manage the electrical loads, That is a great manner to safeguard yourself and your equipment.
I rarely plug in as I use the coach to get from here to there and donot stay in the coach at the end of the journey. That will come later when I retire ( or quit at my present job, there is no retirement in site for me, always something to do)
Hope this helps.
That simple check of Tom's will save $$$
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50 amp service is 25 amps per leg, Two legs coming in, each 120 VAC.
I hate to dispute you Gary, but that statement is absolutely incorrect.
50 amps service consists of two legs coming in, each 120 volts at 50 amps per leg. If you only use one leg, as Tom says he does, he has 50 amps at 120 volts for a total input capacity of 6,000 watts. If he used both legs he would have a total capacity available of 12,000 (12kw) watts.
For those using a 30 amp service, 30 amps at 120 volts provides 3,600 (3.6kw) watts. I have never heard of any standard service that provides 25 amps of service.
Richard
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quote "Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC" unquote
At both the power pole and the gen set the neutral is tied to ground. You should measure the same voltage to ground as you do to neutral.
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"Neutral to leg one should be 120v, leg two to neutral should also be 120v, leg one to leg two should be 240v, ground should not register. Just a good way to protect your self, no matter which way your bus is wired. Good Luck, TomC"
At both the power pole and the gen set the neutral is tied to ground. You should measure the same voltage to ground as you do to neutral.
Stan
Thanks Stan for pointing that out, I missed it and that is very important for everyone to know. The only place you would not, should not, can not (to be safe) read any voltage is between neutral and ground.
Richard
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Stan- thanks for that very important correction on my post. No voltage between the neutral and ground is what I was supposed to say-and a very important reading so you know if there is any "shorting" situations with the wiring. Good Luck, TomC
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Richard,
Thanks for the clarification, YOU are correct. The AWG size required for the 50 amp service warrants the full 50 AMP EACH LEG.
Not sure now, what I thinking then, but you have cleared this up for me and hopefully I did not screw toooo many others up before.
Rich,
thanks for helping this po boy from Weirton WVa with this.
I will wait for the second cup of coffee to set in before typing.
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Richard,
Thanks for the clarification, YOU are correct. The AWG size required for the 50 amp service warrants the full 50 AMP EACH LEG.
Not sure now, what I thinking then, but you have cleared this up for me and hopefully I did not screw toooo many others up before.
Rich,
thanks for helping this po boy from Weirton WVa with this.
I will wait for the second cup of coffee to set in before typing.
Gary, come on down to Spencer & I will furnish the second cup. LOL
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I did not see this post until I posted on the one above it, if phil or Richard want to combine it with this post is fine with me but this may help with assurance you have good shore power connected your RV /Bus before actually connecting up to it. My post has to do with Phil's near catastrophe on his bus at a camp ground that was improperly wired.
Sorry for the double posting on this.
Gary
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That business about the full wire size for 50amps per leg does a nice job of clearing up why 50 amp service has to be 240 volt; if the power was furnished as 120 volts only, then the neutral would have to be two neutrals or about a three gauge wire, if it was even legal to use only one neutral.
Tom Caffrey
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Mine is wired in the standard 50 amp 120/240 volt configuration. It seems silly not to, as the costs are about the same. I have a 20 amp 220/240 outlet in the center bay for those times I need to weld or use the plasma cutter. It's much easier than dragging out that heavy 70' 10-3 cable to weld. Also, I have an outlet in the bus for a portable space heater that runs on 240 volts @ 20 amps. It's very quiet and puts out around 9k btu. It's nice for quickly heating the bus or for sites that have 50 amp service with power included.
I'd wire 'normally' with both legs of 120 volts, neutral, and ground. You can always combine the two legs with an adapter plug or the cable itself. Also, my generator puts out 50 amps @ 120 volts, so my transfer switch combines both legs when it selects generator, or both legs when plugged in.
David
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Richard, Iam hooking up a 50 amp RV pole this weekend and think I got it right,but get confused by different posts and was wondering if you would post little drawing showing wire hook-up.Thanks for any help.
Leon
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Leon, I do not know how to make a drawing to post here. Perhaps someone like Sean will step up to the plate. Sorry
Richard
Richard, Iam hooking up a 50 amp RV pole this weekend and think I got it right,but get confused by different posts and was wondering if you would post little drawing showing wire hook-up.Thanks for any help.
Leon
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Does this work as a picture?
Bare or Green Ground
*
Black 120 volt hot | | 120 volt hot Black or Red
|
White Neutral
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Hi Rachard, Thanks thats perfect,because there were so many adapters with the bus I bought,I was second guessing which receiver to buy. Thanks again.
Leon
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You're welcome, but you really need to thank Stan. He is who posted the drawing. LOL
Richard
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Thanks Stan,am on my way to buy plug as that is configeration of the main extention with out adapters.
thanks again.
Leon
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Stan, When I wired my 50 amp plug from panel box in garage, I put red 110,black 110 , Ground to ground
block, (bare wire), Then white to nuetral block. I read where neutreal and ground should be bonded,should I put both neutral and ground in same block.
I ask question at home- depot and they look at me like Iam crazy. It is working allright, but I don't want to hurt someone or burn up my dream.
Thank Leon
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redbusnut: The only place the ground (bare wire) and neutral (white wire) are connected together is in the service entrance panel (the breaker panel closest to the meter). There are only three wires coming from the utility company to your meter. One of these wires is ground, and in the service entrance panel you connect the bare ground wires and the white neutral wires to the same point. In actual fact, the bare wires are connected directly to the metal box (or to a bus bar connected to the box) and the white wires are connected to a bus bar which is connected to the metal box. From that point on, the bare ground and the white neutral are not connected together. The neutral is a current carrying wire. The ground wire only carries current when there is a fault in the system, to prevent the current from going to ground through your body.
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The reference for clarifying these questions is NFPA standard #70, The National Electrical Code, published by the National Fire Protection Association. If it's not available at the library, or your local fire dep't., it can be purchased through NFPA on line. There are also guidebooks available that explain some of the more complex issues.
Back in my first life I had access to current versions, but not any more. And I won't try to comment on grounding requirements 'cause I'm too rusty! Another resource for guidebooks on the subject is electrical supply houses. That 220 is hot stuff, be careful.
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Stan, Iam going to admit, Iam dumest person on this board, Should I connect nuetral and ground on same bar in panel box.
Thanks Leon
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redbusnut: In your previous post you were talking about the wiring in your garage (I think). If you are still talking about your garage, which I assume has a subpanel, and is not the maiin service entrance panel, then you do not connect the ground and neutral together.
Remember that I am talking about the usual residential service and not industrial service where you may have a splitter box sending 200 amp service to more than one building.
If you have changed course, (without telling us) and you are now talking about your bus, there are different answers depending on how and what your panel is connected to. If it is only hard wired to an onboard genset then it would fall under the rules of main entrance panel. If it is ever connected to shore power, then it is a subpanel with isolated neutral. If an inverter is thrown into the mixture, different wiring is required because of internal wiring in the inverter.
There is a lot of info on this subject in the board archives, including wiring diagrams for different hookups.
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Hi Yo Silver: I try to explain electric and electronic questions in a manner that is safe and functional. The board has members in a multitude of countries that do not use the US codes and regulations.
In this thread, the profile for redthebusnut gives no indication of where he lives. If Leon lives in the US, then I assume that he should meet federal, state and county regulations
I live in Canada where most of the electrical code is much tougher than the US codes. In my previous life I had to make changes to many items imported into Canada that passed inspection in their country of origin.
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Hi Yo Silver, Iam in Canada to, Vancouver
Leon