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RV's typically take 120VAC with an oddball 30 amp receptacle:.Note the center hole is not a terminal.It will work fine with your 10/2 wire, but your breaker is 2-pole unnecessarily - a single-pole breaker would do. (Though, a single pole 30A breaker is kind of an orphan, hardly used for anything - the 2-pole breaker is commonly used for several purposes.)Neutral goes to your neutral bus, ground goes to your ground bus. Hot goes to one side of the 2-pole breaker, the other side is unused.If you wanted to use a NEMA 14-30 connection, you bought the right breaker but the wrong wire. But if you wanted that since 240V/30A is not common with RVs, usually it's 50A if it's 240V.
Ronnie,I’m not talking about a campground or electrician installing a dryer outlet and an RVer jamming the plug into the wrong socket. I’m talking about an unknowing electrician installing the proper RV outlet in your garage, but mistakenly wiring it to 240-volts rather than 120-volts. Since it appears to be a proper RV outlet to the unsuspecting home owner, they just plug their RV into it to check it out, and that’s when the fireworks begins.The reason electricians and DIY homeowners can make this mistake is that a 30-amp/120-volt RV outlet “looks like” a 30-amp/240-volt Dryer outlet. And since that electrician has probably wired in dozens of Dryer outlets while this could be his first RV outlet, that’s why the mistake occurs.
It’s always best to test every unknown outlet for proper voltage and polarity BEFORE plugging in your expensive RV. I am 37 years old and I have been working as an electrician for the past 6 or 7 years, before that I was a helper for8 years. I just cleaned my mother in laws trailer so she can sell it. I have done a ton of work on Mobile Homes and I like a real jerk jammed her 120 volt 30 amp plug into the 240 volt dryer outlet. When nothing was working, I went for the whole trying trying to figure the problem. I thought some idiot miswired the darn thing because I was getting 120 volt on my neutral.
How to Wire up a Travel Trailer 30 Amp Box By Amanda Flanders. SAVE; If you are looking to keep your travel trailer in a lot all season, installing a 30-amp receptacle at the camp site is a useful option. Test the GFCI 30-amp receptacle with a voltage tester and plug in the RV. Amanda Flanders Amanda Flanders has been writing since 2007. RV Advice Need to Know Differences Between 30 and 50 Amps. Mark Polk explains why you can use more electricity in an RV with a 50 amp service then you can in an RV with a 30 amp service. Top Tips From This Video. Plugs on RVs with 30 amp service and 50 amp service differ in design.
Well inside the trailer I was in 120 volt mode but every time I went to outside I was in 240 volt mode. I am just an idiot, I realized my error last night. I just had an electrician do this exact thingwiring a 120 V outlet in a 240 V mode. I had told him in a text to be careful, but he just wired it up wrong. Dummy me, did not check it out with my voltmeter. Luckily, I had a surge protector on, which likely saved my appliances. However, I ran it over to the RV shop and they said that my converter is blown.
The electrician is paying for the new converter. My question is – Should I be concerned about any wiring damage that may cause a fire, etc. From this event? Thanks for the advice!! Yeah, surge protectors will do nothing to protect you from a over-voltage situation like a 120-volt outlet mis-wired with 240-volts. The only thing they’re really good for is protecting you from a nearby lightning strike to the ground. But any kind of direct lightning hit to the electrical wiring is going through them anyways.
So don’t confuse a simple surge protector with something like a Progressive Industries EMS, which has relay contacts to disconnect your RV from over-voltage or under-voltage conditions. And yes, they also include a surge protector circuit for nearby lightning protection and other spikes on the power line from things like pump motors and such.As far as what can be damaged, basically anything with electronics is at risk if it was turned on at the time of the over-voltage condition. While the general wiring in the walls of the RV and the circuit breakers won’t care if they had 120 or 240 volts, you should check your refrigerator, air conditioner, television, inverter, converter, tank monitoring system, etc And the sad thing is that some of these electronic component failures many not show up for a few months.
So be sure to get your RV powered up (once the converter has been replaced) and run all the appliances for a few days, carefully monitoring for anything acting strange. And tell your electrician to keep the insurance claim open for a full year since you could have something electronic fail this fall that was a result of his mis-wiring in the spring.
If his insurance questions this, they can call me and I’ll charge my normal $250/hr consulting rate to educate them about over-voltage failure mechanisms in electronics. What often happens in electronic gear is the filter capacitors that have been exposed to over-voltage begin to out-gas and the case they’re enclosed in begins to swell up. Sort of like a miniature cola can that’s been overheated and tries to burst, but not quite.
Eventually that capacitor will fail, and when it does the circuit will die.Also, transistors don’t do well with over-voltage and their PN junctions will be stresses to the point of failure at some future point. There’s only so many over-voltage spikes they can withstand, because each voltage spike punches away a little more of the insulating layer.But a lot of very modern gear won’t be affected by 240-volts because they have universal switching power supplies designed to run on anything from 90 to 250 volts. Your situation just depends on the type of power supplies in your electronic gear and just how long you exposed everything to 240 volts. I just purchased a used 2003 Keystone RV 5th wheel from an indiviual. The TV and stereo was taken out.
The microwave didn’t work. All 110 volts electrical, converter, battery, slid outs worked, using an extension cord plugged into an 20amp outlet in my garage, to my 30 amp / 120 volt TT cord. I purchased a RV Power Outlet 120 volt 30 amp provides an electrical receptacle in a single enclosure and a 30 amp breaker for my breaker box in my garage. I wired both black & white wires to the breaker & ground to the ground bar. Not thinking that gave 220 volts Bad mistake $$$$$$$. My ac still works, all battery devices lights, slide outs, power jacks works. My frig light works, but says no electrically.
My GFI outlets work, but all 110 lights don’t, maybe more. Need all advice. That is exactly why I wrote this article.
TT-30 RV outlets look a lot like a 30-amp/240-volt dryer plug, so it’s far to easy to wire one up incorrectly. Basically, anything with a circuit board, filament, or motor could be burned out. YOu have to divide and conquer, testing each appliance or device individually. This can be so costly that I’ve seen entire RVs “totaled” since the entire electrical system was toasted. Most of the time the circuit breakers and actual wires are OF, but the fridge, HVAC, Inverter, Converter, Hi-Fi, Television, and monitoring systems can be taken out.
The more modern and expensive the RV, the more electrical appliances and controllers to destroy.Since TT-30 receptacle are so easily miswired, I highly recommend that everyone add an electrical monitoring system to their shore power connection. It’s just too expensive to fix all the fails from an over-voltage condition.
Test everything for proper operation, one piece at a time. You’ll have to take everything apart and inspect the circuit boards for burnt marks and bulging capacitors. Also, use your nose since burnt electronics has a sweet smell that’s hard to miss. Anything with an auto-switching power supply (90 to 250 volts) is likely OK, but anything with old-school single-voltage supplies could be damaged. Things connected to only 12-volts DC are probably OK. But realize that many components have been stressed and might fail in a few weeks or months.
So don’t just turn things on for a quick check. You need to run things for a few hours at least and monitor for a later failure. Yup happened to our parents. They built a new house and handed the electrician the proper outlet they bought at the RV store.and told him it was for an RV and where to install it alongside of their garage. The Idiot wired it up 220 instead of 110 and blew out all the electronics and even melted some of the wiring sealed in the walls.
It was a VERY expensive mistake– and time consuming for the RV repair place to try to correct. Even then, some strange electric things still happened within the RV aftewards. All the control boards for every unit went haywire, including the fridge, water heater and furnace too. Not to mention the TV’s, stereo, DVD player, micro/convection oven, and light fixtures. Every bulb was burned BLACK. The electrician had the audacity to ask them to turn a claim on their homeowners insurance instead of him rectifying the situation. Can you imagine that???
It’s an easy mistake for an electrician who’s never hooked up an RV outlet. Now, I’m not excusing his mistake, but commenting that I understand how he could get confused. And as you noted, I believe the electrical damage caused by plugging a 120-volt RV into an outlet mis-wired with 240-volts can create all sorts of “random” electronic failures months after the incident. If it happened to me, I would ask for the RV to be “totaled” and expect full replacement cost from the electrician’s insurance company.Modern RVs are essentially wired like a smart house, with so many interconnected electronic gadgets that it’s difficult to find and replace EVERYTHING that’s damaged by this type of mistake. Yes every electronic and electrical device in your RV can be fried by a few seconds of over-voltage.
See why I recommend that all RV owners test pedestal outlets for correct voltage, polarity, and grounding BEFORE plugging inMike Sokol. Don’t get me started on reducer/adapters. I get emails every week from RV owners that develop hot-skin conditions, and they’re normally caused by a ground break inside a cheap, imported dogbone adapter. Or someone will adapt a 30-amp outlet to a long 15-amp extension cord, then run it into an RV that doesn’t have a master circuit breaker.
They’re then trying to draw 30-amps through an extension cord rated for only 15 amps of current. Here’s a video I made about overloading extension cords:Mike Sokol. I think that installing a good voltage/surge protection system is the best money you’ll ever spend on your RV. The Progressive Industries products are well engineered and solidly built. Remember, there’s a BIG difference between a “surge suppressor” and a “voltage protector”. The surge suppressor is only good for reducing voltage spikes from nearby lightning strikes, but a voltage protector will identify low or high voltage conditions and disconnect your RV’s electrical system from the incoming power line.
As an electrician/construction administrator for an engineering firm, who just made this very mistake on my father in laws RV, I can tell you the problem does not lie with the electrician. This information should be clearly marked on the dogbone, at the plug on the RV and the receptacle. These items should be clearly marked DO NOT CONNECT TO A 240 VOLT, 30 AMP CIRCUIT!!! CONNECT TO A 120 VOLT, 30 AMP CIRCUIT!!! With so much dollar value riding on the correct and incredibly unusual type of circuit, THEN CLEARLY MARK IT!!! A normal single pole receptacle has different colored screws that indicate connection to designated wires. This receptacle does not.
Neither of the two different dogbones in my possession have any markings indicating the voltage change whatsoever. The original 50 amp, 2 pole service leads one to believe that two hots are acceptable. And for those who are not aware, some relatively simple electronics and a small transformer will create a neutral from a two hots. This is common knowledge in my industry.So yeah, I screwed up and cost myself a ton of money, but don’t try to act like the electrician should have known. Obviously, this is a very common mistake that could be prevented with some $5 stickers. And yes, I’m pretty p’od right now.
I can’t believe that the RV industry is so nonchalant about this occurrence (I called an RV store and they were quite aware of this common mistake). But hey, they get more money out of people having to fix this.Now that my rant is overCan these appliances be fixed? Or do they need to be completely replaced? The inverter/charger is simple enough to replace, but all of the others systems are what concerns me. Fridge, microwave, monitoring systems, water heater, the AC unit still works. Sorry to hear about your problem.
I do agree that there’s not enough markings or obvious differences on a 120-volt TT-30 RV plug to prevent miswiring one as a 240-volt dryer outlet. That’s exactly why I wrote this article after receiving numerous emails from readers about this same sort of mistake.
How often this happens is a mystery, but according to my discussions with Gary Bunzer and Mark Polk, it seems to happen a lot.Now, I don’t work for the RV industry so I don’t know the history of this design. But since the TT-30 receptacles are manufactured by a variety of companies, many of them foreign, marking all of them with big stickers would be problematic. If you look very closely at your TT-30 receptacle you should see a very small marking that states 125-volt max as per NEC specs. But that’s in really small black-on-black writing that nearly impossible to notice.As for repair or replacement of the RV appliances, that’s a roll of the dice. Anything that was turned off during the overvoltage event could probably survive. But many appliances NEVER really turn off, even when you hit the off switch.
I would contact each of the manufacturers to see if they can suggest what components might be damaged by 240-volts, and then inspect each appliance for blown fuses and obvious power supply component damage such as blown capacitors and diodes. I think that less expensive appliances such as a microwave may be too expensive to fix compared to replacement, but certainly you should be able to get a swapped control board for a built-in refrigerator. And you might find out if their homeowners insurance will cover the cost of replacement due to overvoltage. Of course there will be a deductible to pay but that’s certainly less than the full bill. Thanks for the reply and the website. Being an electrician/gigging musician/field engineer (Construction Administrator is just a fancy title), I find this site to be very informative and useful.I already have a new converter and new battery in my possession. The plan is to install them after work today.
Hopefully, it won’t all be bad news from there. I already know the microwave is toast, probably the TV and DVD player too. I do hold out some hope for the equipment powered by 12 VDC, since I unplugged the trailer immediately upon discovery of the failed smoke test.Either way, thanks again. Just an update that might be useful for anyone that unknowingly follows in my footsteps of stupidity. I installed the new converter and battery.The only losses, were the electronics plugged directly into the 120 Volt outlets in the trailer: the microwave, TV and DVD player.
All others systems have been fully tested and are operational. This may be due to the fact that the converter was directly in line with all a other systems and therefore protected them. Wiring insulation is typically rated for 600 Volts, which was the case with this trailer, so I would be very leery of anyone who says the wiring is bad within the trailer in this type of over voltage situation.
Seems like a way to take advantage of uninformed customers.Mike,Thanks again for the website, keep up the good work! Paul – When you say “converter”, do you mean “inverter” — the electrical component that is tied to the 120V system?
It normally takes input power from the shore cord and “through supplies” this power to the 120V circuits in the RV and also re-directs some of that input current to charge the house batteries; when the shore power (or on-board generator) is disconnected, the inverter draws DC power from the batteries, inverts it to 120V and supplies it to the 120V circuits in the RV.The inverter is a major first-step component in the supply of current into an RV from shore power. (We will ignore the fact – for the moment – that1) some RV’s are wired like a house and will supply 240V from a 50Amp/240 shore supply to electric cooking ranges, clothes dryers, etc, while splitting legs to supply 120V to ordinary 120 V circuits;2) some RV’s are set up to receive 240V from the shore cord but immediately “split” the legs so that the only power circuits on the RV are 120V supply;3) other RV’s are set up to only receive 120V from their shore cord. These various systems must be considered when designing or troubleshooting an RV electrical system but aren’t really relevant to our discussion here.)Unfortunately for simple description, there are devices which are called “converters” that are sometimes used on RV’s.
These are components that take one voltage of DC and provide output at another DC voltage; for instance, if the house storage batteries on the RV are 12V and it’s necessary to supply 24V to a component on the bus, a 12V DC – to – 24V DC converter can be used. But “converters” are very different from “inverters”, so to keep discussion clear, it’s necessary to separate the terms as we used them and be very accurate as to what components we’re talking about.I’m sorry to hear of your troubles caused by the poor labeling on the 30Amp connector. I especially regret the cost of the components ruined and I hope that you’ve worked through all the damage done.Best wishes, Bruce H NC USA. Bruce,It is an RV Converter/battery charger. See the link to the manual. It converts AC to DC.You are correct in how an inverter works, but this converter coverts 240 Volts to DC.
I realize that there are different types of converters. The trailer is set up for 240 Volt, 50 Amp shore power and my mistake was assuming and rushing to hook up a 30 Amp receptacle.
It would have been painless, if I just used a 240 Volt, 50 Amp receptacle fed by the existing 240 Volt, 30 Amp circuit breaker that I was trying to use. That is more available Volt-Amps than the 120 Volt, 30 Amp breakdown that the dog bone would provide.
So simple and yet such a pain in theThis is the first time in 22 years of working in the electrical industry that I failed a smoke test. Embarrassing!!!Moral of the storyKnow exactly what you’re getting into before you plug something up.Thanks a bunch for the reply,Paul. The trailer is a mixture of 120 volt circuits and 12 VDC as Mike mentions (that would be a great article, by the way).
Like I mentioned earlier, with all of the different possiblilties regarding voltages, things should be clearly marked throughout the trailer, extension chords, dog ones and receptacles. There is just too much money and safety riding on this potential mistake.One thing we do in our construction specifications, is require contractors to clearly mark everything. The NEC is going in this direction too, regarding increased requirements for Arc-Flash Warning Stickers. Stickers are cheap, easy to install and could potentially save a life. Ok, so I understand this.There is a 12V system with a battery and when the RV is not plugged into “shore power”, there is 12V available from the battery; when it is plugged in, the “converter” provides 12V into the system and charges the battery (.ies).
There is also a 120V system and when the RV is plugged into shore power there is 120V available from that system and when it’s unplugged, there is no power available from this system.Is this correct? No 120V unless it’s “plugged in”? Yep, you got it.
Certain circuits do not run without the shore power. The converter runs off of one circuit breaker from the shore power supplied electrical panel. The converter, battery and truck power can all provide power to the fuse block that supplies the 12 VDC circuits.I just went back to read all of my posts and it’s pretty obvious to me that I have learned a lot in the last few weeks. I really appreciate your response and Mike’s page. This was clearly the most informative site regarding this subject.Thanks,Paul. Thanks for that info, Paul.
I assume that you know that if an inverter were put into the system replacing the converter, it would act as the converter does but also does more.When the RV is plugged in, the inverter would provide 12V to the 12V system and charge the battery; it would also pass through 120V to the 120V wiring system. When the RV is no longer plugged in, the 12V system would be powered direct from the battery and the inverter would pull power from the battery and provide 120V to the 120V system. When the vehicle is going down the road, either the engine alternator or an auxiliary alternator would provide 12V to the battery, keeping it charged and providing power to both circuits (the 12V directly and the 120V through the inverter). A generator could be installed in the RV but it would just provide 120V and operate like a shore cord.Using a system like this, you always have power to 12V and 120V systems; but it should be added that pulling 120V from the battery(ies) can run the batteries down pretty quickly.
Since this is pretty flexible and provides power to all the circuits in many situation, it’s more useful than the converter alone. (But, an inverter is a lot more expensive than a converter, and there is the issue of the batteries being run down.). Bill,I’m guessing that your motorhome uses a 30-amp/120-volt shore power plug, technically called a TT-30. If that’s the case I would recommend that you have your home outlet (Edison outlet) changed out for a small RV receptacle box. Something like this would do the trick: Also, you’ll need to check to see what size Romex wire is already run there, but it’s probably 12-gauge which is rated for a max of 20 amperes. If so, you can’t upsize the circuit breaker to 30 amps, but it’s OK to feed a 30-amp outlet with a 20-amp circuit breaker and 12-gauge Romex.
However, I would suggest you label the TT-30 outlet as “20 amps” so that no future inspector has an issue with it. As long as you don’t have everything running at once in your motorhome, you’ll probably be fine with 20 amps of power. This is WAY better than using some sort of 20 to 30 amp dogbone adapter plugged into your existing outlet, since they’re notorious for failing and allowing a hot skin condition to occur on your RV. So- I actually did this all myself— I personally wired the connection a 220 (240v) and fried my trailer-even though i made an idiots mistake I am (at the moment) feeling confident i can go through and replace what is needed and sort it all outso far i diagnosed that theA/C doesn’t turn onFridge Doesn’t turn onNo outlets workMicrowave does work! That said, i am assuming the converter (inverter?) is friedI volt tested my main breaker panel and I am getting no voltage on it I am assuming this is because of the converter being fried in the connection before hand?so before i go replacing everything, is there a chance that when i replace the converter the other non working items may click on (main breakers and such?)just curious. I am the idiot everyone talks about. I made a “converter” out of a dryer cord and a 30 amp receptacle and plugged it in.
Fried my 2500 watt inverter and microwave. Cost me $2000.I never thought it was 240, just never entered my mind. (small as it seems now). But I was also under the stupid impression that my surge system would suppress the error.
Heard a loud “bang” and everything went dead. Needed a new inverter for $1600 and a new microwave/convection oven for $400 (used).I have been kicking myself every day since.
I am a cheap sob and wasting money on stupidity makes me nuts. If we disqualified anyone who has done something “not smart”, we wouldn’t have any readers or any followers.Sorry it happened that way for you. One question, if the only outlet available for an RV hookup is a 240V and the vehicle is wired for a 120V panel, is it possible (or if possible, good practice) to wire one “hot leg”, neutral, and ground and use feed that 120V power into the RV? I know that it would be “out of balance” and the neutral would be carrying all the “negative load” but would that be a bad thing?
Is the gauge of a neutral wire usually large enough to carry the full return path of one leg of a 240V circuit?And the reverse, if you have only a 120V and the RV is wired for 240V, can you supply the 120V feed to both pins of the 240V plug (neutral and ground connecting straight, of course)? You wouldn’t have “phase” and I guess that the total power use would again be “return path” down the neutral but 120V does that anyway.Implicit in this is the inverter being set to limit power use to approx. 14A on a 20A/120V circuit.The details are tricky.
Thanks, BH NC USA. Maybe, but a lot of electronics will suffer stressed components such as bulged capacitors and transistor junctions that have been damaged. So over-voltaged appliances might work for a few days or even a few month, and then just die. If there’s an insurance claim you should ask for them to keep the ticket open for a year in case your refrigerator dies.
However, it sounds like you did this yourself, so the best you can do is hope that nothing else dies. So I would use everything you can as much as you can for the next few weeks, and most of the damaged gear will probably show up soon.
Yes, that’s a safe way to do this. That’s because a 240-volt receptacle in the USA is really two separate 120=volt legs that are 180 degrees out of phase with each other.
So a 50-amp/240-volt shore power plus uses both 120-volt legs, while a 30-amp adapter only uses one of the incoming power lets which results in 120-volts being supplied to the RV. Where electricians and DIY guys get into trouble is when they improperly use both legs of the incoming 240-volt wiring to connect to a 30-amp/120-volt TT-30 plug.
That’s what will destroy an RV’s electrical system in a few seconds. I have a situation that’s a little different, we had the panel at our church replaced which is a 3-phase delta system (the third leg is 240v to ground but still only 240v to the remaining two legs. So the 50 amp breaker for the rv was put across the high leg because it’s “240” so any 240 appliance will work fine. What the electrician didn’t realize is that an rv is not a true 240 it’s actually two 120’s. So technically I can’t blame the electrician since it would of worked on any other appliance.Will I have all the same problems or will it be less or worse? The ac blower and compresser run but does not cool, the display on the microwave doesn’t work but the light comes on when you open the door, the display on the fridge works but not sure if it cools. The slides all work and the tv, all the 12volt lighting works but it could of still been powered by the battery.
I didn’t get a chance to check everything since I just packed it back up and came home since I couldn’t stay in it. Stanley,Well, you’ll have exactly the same type of over-voltage damage as a mis-wired TT-30 outlet. While High-Leg Delta panels never exist in a residential home, they should be well known to industrial and commercial electricians since they were very popular in the 60’s and 70’s in commercial buildings that used mostly 3-phase motors. I’ve personally been in dozens of churches with this type of panel and also know of at least one campground that miswired a whole bunch of pedestals from the “High-Leg” bus in the panel.
Lots of damage with that one. I just don’t understand why electricians don’t use a meter to check new circuits.
It only takes a few seconds and will save thousands of dollars in damage. Likely everything with a circuit board that was running from the 120-volt circuit is damaged. Do you or the electrician have insurance to cover this? With all due respect, they don’t know what they’re talking about. A lot of 240-volt appliances use the neutral and one hot leg to drive a 120 volt motor (in a clothes dryer) or 120-volt control circuitry (in a stove).
So there’s a 50/50 chance that this mis-wiring condition would have blown up an appliance. Your electrician created a 14-50 receptacle with a serious code violation that should never have passed inspection. The next person who plugged into that outlet would also have blown up their appliance or RV. Don’t ask an electrician about this, you need to talk to an electrical inspector. Electricians who wire outlets without metering them are asking for trouble. Again, a slightly different issue.
I’ve recently moved to a new storage site. They have three-pin 240V outlets; there are two female “blade” terminals and one female round terminal in each outlet/socket. I’ve checked with a meter, they show 120V from each blade terminal to the round terminal and 240V between the two blade terminals. My RV is wired with a 14-50 plug with four rectangular blade connectors. It splits to two 120V legs at the main breaker box; there are no 240V devices in my RV.What do I do?
I’m assuming that I’ll have to ask the storage owner to convert to a 14-50 socket. What will that involve, such as running new wiring, etc.?Many thanks, I’ve learned a lot from your site and forum. Bruce H, North Carolina, USA. Well, you’re most likely looking at a 30-amp/240-volt dryer outlet that became popular (and was code compliant) in the 1960’s as a way to save copper. You can still find them in a lot of US homes, and they’re grandfathered in so homeowners don’t need to replace them. But as far as using them with an adapter to power an RV that seems like a bad idea. They don’t have a dedicated ground wire, hence the 3 wires vs.
The 4 wires required by your RV’s shore power plug. I think you should ask the storage facility to install a proper receptacle with correct wiring. Yes, they’ll need to run new wiring back to the service panel to do this correctly. They can’t just put in a 14-50 receptacle and bootleg the ground to the neutral wire. However, since this is a storage facility and doesn’t need full 50-amps, they can likely run even a 20-amp breaker with 12-gauge wire to the 50 amp receptacle, marking it for reduced amperage.
That will save some money on copper and maybe get the job done. Yes, that’s correct. Most consumers don’t realize that we have 240-volts coming into our homes in the USA, but it’s split in half with the neutral. So Neutral to either Hot should measure 120 volts, and Hot1 to Hot2 should measure either 240 volts or 208 volts (depending if it’s wired into a single-phase panel or a 3-phase panel).
Ground to Neutral should measure very close to zero volts if there’s no load on the panel, but can go as high as 3 volts during high current draw in the panel, and still be in code compliance. I personally have not encountered 240AC pedestals with any of my RVs over two+ decades.When I was working as an RV Tech for about 10 years before re-retiring, I encountered three 240VAC installations that wiped out almost all electronics in the RVs. The three cases involved having a electrical contractor (or friend?) installing the receptacle at a private residence.
As I recall, the contractors paid for the repairs of damaged equipment and labor.I enjoy and appreciate your contributions to RV Travel for our education on electrical safety.Thank you. I am so lucky that I happened across this site.
I am an electrician in Colorado and was called by this client today to wire up his old 1980’s Airsteam on his ranch. I looked at the plug and thought, no problem, went to home Depot and bought supplies to wire up that dryer looking plug for 240 volt.I was even going to cut off the old corroded head and put on a new one.
Wow, I would have screwed up big time. Now I know what to do. I guess I should go look in the code book but I have a feeling It won’t tell me about this. I’m going to tell all my electrician friend about this and see if any of them are aware, I bet not.
Thanks Mike for saving me a couple of grand and an endless headache.Please put me on your mailing listSteve.