Hi Everyone!
On the side of my 1994 U280 a sticker saying "120/240 Volt 50 Amps".
Question: Will my RV really take "240 Volts", or do they really mean "Two 120 volt circuits"? I thought the standard NEMA 14-50R connection was really two 120 volt 50 amp connections (each). I've been told repeatedly RVs don't have 240 volt connections.
Rest easy, I'm not about to try to plug this into my dryer connection at home ;-)
However, I did find it odd. When it says "240 volts", what exactly does that mean?
Thanks
Mark
Yes, you have TWO hots, a neutral and a ground. 240 VAC between the two hots.
Just like most appliances in your house with the exception of BIG thing like A/C, ovens, dryers, etc; things in your motorhome run on 120 VAC (one hot).
If you look in the 120 main breaker box (foot of bed), it is just like your house box with legs/breakers alternating between L1, L2, L1, L2, etc.
50 amp RV is the same as 50 amp stove, etc.
30 amp RV is NOT, repeat NOT, repeat NOT the same as house 30.
Some Newell coaches take advantage of the 240V, but that is not the industry standard. There is no reason why you couldn't have a 240V appliance (a/c maybe? dryer?), but it would take a bit of work and $$$.
To be clear, there were NO 240 VAC appliances as original equipment, at least in that vintage coach (I have no information on the new/huge Foretravels). 100% 120 VAC from ONE of the two hots.
As a tech, I have seen so many RVer's bend the tangs on a 30 amp plug or adapter, and plug their coach into a 220 outlet.
I picked up a couple of free Prosine inverters, which were easily fixed, but replaced under warranty by their insurance.
One guy was building a new home, electrician wired the 30 amp RV plug to 220. It took a bunch of stuff out. He paid out of pocket to get it all fixed, and 2 days later called me, he plugged it into 220 again. Same replacement of, microwave, converter etc.
I just worked on a Japanese Toyota chassis mount RV imported. RH steer and all.
Has a american 120 volt Onan gen set, and Dometic air con. But in Japan, everything is 100 volts. Has a transformer for the gen set when it is running, but only a 100 amp shore plug with wimpy power cord. You can not run the air con plugged in, only off gen set. Transfer switch is setup that way. Bet people in camp grounds like that!
Fun part is, everything was wired nice, but all labeled in Japanese.
Fun Times
Chris
Not to confuse; just to clarify: Our 1995 U320 uses both legs of the 240 Volt, 50 Amp connection, but for different 120 Volt circuits. Therefore, we do use from both of the two hots, but not as a 240 Volt connection for any single appliance.
And this is where the problems come in.
Where we're staying right now, the metered power pole has one power lead and one neutral. So my 50A breaker is connected to two L1. Not a problem for me since my 50A is strictly 120 volts, L1 and L2. Since they're never combined to make 240 VAC I have nothing to worry about.
So back to the original poster's post. His vehicles placard states This connection is for 120/240 VAC 3-pole, 4-wire 60 Hz 50 A supply.
If the power pole has two phases connected you have the potential for 240 VAC. If only one phase then you only have 120 VAC available.
120/240 get it?
Your coach / appliances don't know (or care) if you are connected to a 120/240 volt pedestal (L1 - L2 opposite phases) or a 120/120 volt pedestal (L1 - L2 on the same phase- and yes I have seen some wired this way). BUT........with the neutral conductor in your 50 amp cord .... it does matter. IF TOO MANY loads are on at the same time, it could become overloaded and over heat.
In a 120/240 volt system the neutral conductor carries the DIFFERENCE in current between L1 & L2
If both L1 & L2 are on the same phase the neutral will carry the SUM of the current of both L1 & L2.
This is what I dislike about our 120/120 volt wired 10 KW generator, and with that being said we never run enough appliances at the same time for it to be a problem.
So.............. enough about neutral conductors for today. ^.^d
If you are plugged into a any receptical or borrow an extension cord, or a portable generator at least use a $5 plug checker on it for hot nuetral polarity, and more importantly ground fault. I had my coach plugged in to a 15 amp cord with a bad ground. The result is called RV hot skin and can be deadly/fatal. I just happened to be wet sanding an area on the front of the coach and would lay the sand paper on the metal bumper every now and then I kinda noticed a very slight tickle when I grabbed the sand paper. Grabbed my multi meter put one lead on the bumper one lead on the wet concrete. IRC somewhere in the 40-45 volt ac range. Luckily I did not die. Voltage/power supply protection should be standard on rv, but it's not and/or wasn't at the time.
So, about that surge protector idea: I've been reading a lot about Surge Guard, Camco, EMP, Progressive Industries, and the like.
Ideally, what I would like to do is:
1) Protect my RV both from the wired power connection AND my 10Kw Powertech generator
2) Be able to check polarity and voltage of incoming power to the RV
3) Protect/condition the power to reduce the risk of over/under power and surges to the RV and appliances.
Do many people on this forum have such protection, and what are they using? Are they using one of the "portable" (plug in) solutions, or a hard-wired solution? Currently, I'm leaning in the direction of hard-wired, but I'm learning so much, I don't want to commit until I have a fuller understanding of the issues.
Thanks!
I use the Portable Surge Guard Protector, 50 amp.
Bought it brand new for $20.00 with 30 to 50 adapter at a yard sale.
Tells me everything I need to know about what's on line.
Now lets chat about Mexico power sources just for giggles....LOL
Chris
P.S. Great responses on here from knowledgeable people
RE:
1) Protect my RV both from the wired power connection AND my 10Kw Powertech generator
2) Be able to check polarity and voltage of incoming power to the RV
3) Protect/condition the power to reduce the risk of over/under power and surges to the RV and appliances.
Progressive Industries EMS hard-wired AFTER the transfer switch & BEFORE the main circuit breaker panel will protect from #1, and prevent #2 from hurting coach, and protect from #3 over/under.
Build your own polarity / voltage tester will check #2 before plugging shore cable to campground pedestal. Several home made plans available.
Portables are theft-able and may not be fully weather proof, and offers no protection from generator issues.
Nothing conditions, but Autoformer will increase some low voltage levels and should only be used when needed and necessary.
You are considering very important protectors. Learn more and do it. Make it happen for your coach.
Barry
A year or two ago I made a cheap test device to plug into the 50A outlet to check on voltage and proper connections. All it is is a 50A cord attached to two normal outlets. One leg is wired to each outlet. Each outlet has a digital volt meter and a polarity tester. I added a 240V neon light that comes on if the outlet is wired for 240V. I don't have anything that needs (or wants) 240V, but it was a pretty cheap addition.
When we were getting the new television antenna I noticed a 30A to 20A adapter that was pretty cheap. Since we're plugged into 30A outlets sometimes, I bought it. I then added a three-outlet tap that I already had. Now, if we're going to be at a 30A site I'll take one of the polarity testers and a volt meter from the 50A tester and put them on the 30A one. Yes, I have a PI 30A portable protector, but the lights on it are kind of hard to see sometimes and it doesn't tell me anything about voltage.
Eventually I'd like to get one of those Progressive Industries 50A hard-wired devices and then I won't need the others.
I bought a 50 Amp Power Pal back when they were still for sale. Kind cool. When we arrive at our parking spot I jump out and plug it in before doing anything else. After it gives me a OK, I plug in our portable Progressive EMS and let it check the outlet. If they both are happy, I figure its safe to hook up the coach.
RV Campground Voltage Tester Protects Your RV (https://50amppowerpal.com).
For the new members here is a link to what David is talking about in reply #12. There are several ways to make one, choose one that works for you. We always use this device prior to plugging into any shore plug.
Pedestal Tester (https://www.foreforums.com/index.php?topic=31712.msg280771#msg280771)
Mike
OR if you are save working around 240 VAC, you can check an RV 50 amp outlet with a voltmeter with probes in less than 30 seconds:
Either outer straight to center straight= 120 VAC= hot to neutral
Either outer straight to center round= 120 VAC= hot to ground
Center straight to center round= 0 VAC= neutral to ground
Outer straight to outer straight= 240 VAC= hot to hot
Anyone know the answer? In the rv park I am in today, the pedestal tests ok with a volt meter. See attached photos of my portable surge protector and my neighbors. More mysterious, some days the portable units both show all ok, with all lights green.
Mine model 44290 shows "Reverse Polarity", my neighbors 44270 shows "L1 and Neutral Reversed".
Sounds like a loose ground at their source.
You know when you go to the cardiologist and they take your blood pressure manually? Same principle here. If you do all of the checks listed by Mr. Wolfe and they show correct. Be happy, don't worry.
Sometimes a voltmeter will show everything is ok but there are loose or bad connections. As soon as you try to put it under load. See if you can leave the surge connected but loose and then do the manual test between receptical and plug
Shhhhhh! The pitfalls of using a high impedance voltmeter are for another lesson.
And, this is the reason we keep a large-readout digital voltmeter plugged into an outlet in the coach where it is easily visible. Check it when turning on large loads, in the afternoon when everyone is running their A/C, etc.
Only slight "hole" in that is that it only checks one hot. But, so does the built-in/OE voltmeter.
Maybe more suitable for the What I Did Today list but,
I finished up installing my 50A outlet on the power pole. Now this is some ancient box of a type I've never seen before, and it's full of cob webs and missing the safety cover, and the 30A plug is hanging from the breaker with too small wire and very classy black tape for a box.
That being said, I do have 2-phase, but I went ahead and installed my new 30A double breaker and 10 AWG wire. Scared myself before I realized the test probes are too short to reach the contacts in the socket, but in the end I have 120 X 2, 240, 0 and 0.
I also have 120V and a green light on my Power Watch meter with both air conditioners chugging away on this 90° Georgia day.
Happy happy, Art.