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Old 08-07-2022, 01:34 PM   #1
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50 amp to 30 amp adapter question

Does the adapters for 30 amp to 50 amp, provide power to both legs of the 50 amp plug? If not what do you do to ensure both incoming legs are hot in the panel on a 50 amp set-up. Everything I have is 120v so no worries about the 120 on both legs of the 50 amp circuit.

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Old 08-07-2022, 03:05 PM   #2
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you can walk into walmart if you want and buy a 50-30 cord right off of the shelf for i think 20-30$ as long as you are confident in your internal wiring, main breaker box for 30 amp you should be golden.
where are you grounded?
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Old 08-07-2022, 03:47 PM   #3
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i still want a response for where they are grounded.
i do to much commercial industrial work with clueless sparkies.
that doesnt matter hear because a bus body is grounded differently?
only reason i asked?
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Old 08-07-2022, 03:48 PM   #4
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Sorry for the confusion I have a 50 amp Service AWG 6-4 coming into the bus, currently just ran underneath the bus. I do have a transfer switch Surge Guard 41260. for the generator two 120v legs at 35 amps each. If I go to a 30 amp rv hookup, does the adapter provide 120v to both legs of the 50 amp plug or does only 1/2 of my stuff will work as it only powers one leg of the 50 amp cable?
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Old 08-07-2022, 04:18 PM   #5
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neither sounds correct to me but i am not an electrician.
where is your ground?
pictures might help?
12v 15 amp will give you a tingle 24v 15 amp will hurt you 30-50 amp 120 can kill you and anyone with you?
if you are asking these questions?
do you know who did the electrical in you build?
they are the ones that should be answering your questions? not a forum where you ask how to finish it? the plug in is simple and if you were not already told that or your sparky that installed your wiring didnt know that? might want to invest and install a couple of fire extinquishers and learn how to use them.
its a PASS method.
pull the pin.
aim at the base of the fire.
squeeze the trigger.
and sweep at the base of the fire.
basic fire extinguisher training ?
everyone should have one in there home and in you conversion.
co2 detector
fire alarm?
not just cause i come from a firefighter /EMS family in texas and was in the marine corp.
the safety training/advice caint stop.
please CO2 detectors and and propane detectors and if you dont hard wire then thats more batteries you have to keep up with.
some of that is stuff in my head and since an electrical build came up i went threw my layout and saw the detector stuff which i have already wired far.
but a fire extinqisher is something some dont think about.
was not trying to be a SAFETY bulletin board?
but the issues are real.
and the first responders have to figure it out.
TV shows?
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Old 08-07-2022, 04:23 PM   #6
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Good Advise

All of the Above.

Jolly Roger is trying to help keep you & yours safe.

A photo of the panel interior, terminations, please.
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Old 08-07-2022, 08:21 PM   #7
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I believe he is asking if he goes from 30 amp to 50 amp will he be hot on both 50 amp legs and the answer to that is NO!. 30 amp is one ground, one neutral and one hot which does not branch into 2 hot legs when trying to convert into 50 amp.
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Old 08-08-2022, 05:42 AM   #8
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Yes I am asking just about the adapter only. Does a 30 amp adapter supply 120v to both legs of the 50 amp side? As for the other comments the neutrals and ground need to be separated in a panel. When on shore power the ground is bonded to the bus and the neutral is kept away from the bus to be bonded back to the pedestal. When on the generator/ inverter the neutral will be bonded back to the generator or inverter at their proper locations all of this switching will take place in the transfer switch. My inverter does a have an internal transfer switch.



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Old 08-08-2022, 09:26 AM   #9
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Yes, the RV style 30-50 adapters just tie both load lines of the 50 amp plug to the single load line of the 30 amp end.
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Old 08-08-2022, 12:45 PM   #10
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Originally Posted by ennonne View Post
Yes, the RV style 30-50 adapters just tie both load lines of the 50 amp plug to the single load line of the 30 amp end.
This would make sense because as I have heard from multiple places, a 50 amp *RV* hookup does *not* provide 240V service, meaning the two 120V legs aren't on different power phases. So in other words, a 50 amp RV hookup will not give you 240V if you measure between the two "hot" legs.

Other kinds of 50 amp hookups that are usually used for home appliances or commercial/industrial applications *do* provide two phase hot legs and therefore will give you 240V.
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Old 08-08-2022, 12:49 PM   #11
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From https://www.getawaycouple.com/instal...-plug-at-home/:

"How Many Volts Does a 50 Amp Service RV Support?
Despite its dual hot pins, a 50-amp service supports 120V. The two hot pins are not combined to increase the voltage.

The two 120V hot pins provide separate 50-amp, 120-volt feeds to provide more wattage to operate larger appliances."
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Old 08-08-2022, 03:00 PM   #12
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Originally Posted by ennonne View Post
Yes, the RV style 30-50 adapters just tie both load lines of the 50 amp plug to the single load line of the 30 amp end.
Great topic!

I think you meant they just tie one load line to the single load line on the 30 amp end.

Which means of course you will NOT have 220 in the bus.

While it is true that 50A pedestals make available power from both sides of a single phase three wire supply, a.k.a. 'standard' 240 volt supply no different that what might be in your house, how your bus will use that power depends on how your bus is wired and what adapter cable connects the pedestal and the bus.

Let's assume for the moment the pedestal is wired correctly. There are a number of reasons why we shouldn't automatically assume that, but for this discussion, let's say it's a professional job correctly done.

If your bus has a 30 amp inlet and you use an adapter to plug your 30 amp inlet into a 50 amp pedestal, the adapter cable simply takes one hot leg of the power and feeds your bus, so you still have only 120 volts at the bus, not 240.

If you have a 50 amp inlet in your bus and you use a standard 50 amp cable to connect to a 50 amp pedestal, then you will have both sides of the phase available at your bus subpanel and your bus will have 240 volts.

Going in the other direction, a 30 amp pedestal properly wired up is also just 120 volts, like a house receptacle, except it has more amps available.

If you get an adapter to plug your 30 amp bus inlet into a 20 amp outlet, like in a garage, you only have 120 volts and 20 amps, but maybe not enough power. That will typically pop the circuit breaker in the garage or house if your power demand is greater exceeds the branch circuit rating of 20 amps.
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Old 08-08-2022, 03:46 PM   #13
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Thank you for the answers for both legs being hot, makes my life easier. Are most 50 amp rv hookup 120 or 240 volt at campgrounds.



Just a note follow the directions for bonding and grounding for each equipment you add to your bus to ensure it works correctly and does not hurt anyone. Wrongly bonded equipment can kill especially with a large metal exterior of a bus and bare feet.
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Old 08-08-2022, 06:15 PM   #14
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Quote:
Originally Posted by dbsoundman View Post
From https://www.getawaycouple.com/instal...-plug-at-home/:

"How Many Volts Does a 50 Amp Service RV Support?
Despite its dual hot pins, a 50-amp service supports 120V. The two hot pins are not combined to increase the voltage.

The two 120V hot pins provide separate 50-amp, 120-volt feeds to provide more wattage to operate larger appliances."
Sadly, not true. That site had incorrect information. Where he says in the text "Despite its dual hot pins, a 50-amp service supports 120V. The two hot pins are not combined to increase the voltage." he's completely wrong.

I can't explain why he was bum information there. If you watch the video you'll see the guy installed a double pole 50 amp breaker, which pulls from each side of the split phase (thus 240 volts). In that video he literally doesn't know what he's talking about, which is scary considering the topic is how to wire your own 50 amp receptacle.

Easy to misunderstand, then easier to replicate the bad info, sorry!

Don't take my word for it. You can verify this by looking at any RV pedestal wiring diagram. A NEMA 14-50 can ONLY be wired one way: 240 volts (both sides of a split phase).

The confusion may come from how a 30-50 dogleg works. If you plug a 50 amp RV into a 30 amp pedestal (using the proper adapter) you get only one side of the split phase, but it powers both sides of the RV panel. I have no idea how RVs deal with this if they have big appliances that normally run on 240 but I'm guessing they just don't run, or the owners know they won't work properly.
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Old 08-08-2022, 09:58 PM   #15
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Originally Posted by ism minerals View Post
Thank you for the answers for both legs being hot, makes my life easier. Are most 50 amp rv hookup 120 or 240 volt at campgrounds.
All 50 amp hookups are 240 volts but note my other reply on important details.
Quote:
Just a note follow the directions for bonding and grounding for each equipment you add to your bus to ensure it works correctly and does not hurt anyone. Wrongly bonded equipment can kill especially with a large metal exterior of a bus and bare feet.
Another important point. There are some good threads here on bonding and grounding. Still some differences of opinion but pretty much all the information you need to make up your own mind on how to put your bus together.
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Old 08-09-2022, 05:19 AM   #16
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Thank you Rucker and everyone else for the reply, I think the only thing I would consider for 240v is a hot water heater, but I got a tank-less LP unit. And well maybe a 240v outlet for on the exterior of the bus for my welder But I think that is being a little ridiculous.




On the bonding and grounding issues I am going to follow the directions of each piece of equipment, they are all made for the RV world. The generator and the inverter will be physically isolated from the chassis, but be bonded through their respective grounding lugs.



The Inverter has its own transfer pass through for the generator magnum energy for ms2812 and the transfer switch is a Surge guard 41260 which can do 120/240v and has some protection for open neutral and reverse polarity ( hot and neutral mixed up ?)
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Old 08-09-2022, 06:18 AM   #17
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im part of the fire extinguisher squad. no wisdom... just my 2 cents.

i've never tried it, but i believe if i plug my 50a camper into a 30a camp pedestal, only half of my panel will work. if a dog bone was wired to connect the 2 sides, that would cause all kinds of issues..... overloaded for sure, and mixing phase/voltage.

it sounds like trouble.

i have 3 - 240v appliances on board, 2 air heaters, and a stove. the heaters don't even use a neutral.
my 120v is a water heater and air conditioners (2 on separate legs)

i think a dogbone would clearly label its internal wiring

if i wired an external outlet, it'd be another rv 50a, so neighbors could plug in. i'd put the same end on my welder to use it on the road if needed.
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Old 08-09-2022, 01:40 PM   #18
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im part of the fire extinguisher squad. no wisdom... just my 2 cents.

i've never tried it, but i believe if i plug my 50a camper into a 30a camp pedestal, only half of my panel will work. if a dog bone was wired to connect the 2 sides, that would cause all kinds of issues..... overloaded for sure, and mixing phase/voltage.
A 30-50 dogbone is wired to provide 120 volts from one side of the pedestal to BOTH legs of the bus/rv panel. The Internet often replicates information from one site to another, sometimes wrong, but often missing the critical information-in this case, very few if any RVs utilize 240 volt devices. I know this is true because I read it on the Internet....

I checked out 5 Internet sites that discuss the use of dogbones. All five correctly state the 50-30 dogbone feeds both sides of your bus panel with only one leg of the 50 amp receptacle.

Three of the five sites I checked are silent on the question 'but what about 240 volt appliances in the RV' while the other two state 'few if any RVs have 240 volt appliances'.

A 50-30 dogbone is not an issue. Unless...

Quote:
it sounds like trouble.

i have 3 - 240v appliances on board, 2 air heaters, and a stove. the heaters don't even use a neutral.
my 120v is a water heater and air conditioners (2 on separate legs)
Unless you use 240 volt appliances in your build.

I know that many appliances simply stop working correctly if only one leg of the 240 service is cut. Dryers, for instance, may spin, but they won't dry (no heat because the 240 volt circuit is open). I don't know how they will run if there is power to the 240 volt circut but it's only 120 volts, a condition you'll have if you put a 50-30 dogbone on your particular build. Will it draw more amps, blow fuses?

More importantly if you have an inverter that runs on 240 volt shore power you may have to stick with 50 amp pedestals and not use 50-30 dogbones.

I guess when we call it 'house wiring' we'll need to be more specific when it comes to 240 volt appliances on the bus.
Quote:
if i wired an external outlet, it'd be another rv 50a, so neighbors could plug in. i'd put the same end on my welder to use it on the road if needed.
The good news is the 50 amp outlet is standard, and can be used for any 240 volt purpose.
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Old 08-09-2022, 03:30 PM   #19
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Originally Posted by dbsoundman View Post
This would make sense because as I have heard from multiple places, a 50 amp *RV* hookup does *not* provide 240V service, meaning the two 120V legs aren't on different power phases. So in other words, a 50 amp RV hookup will not give you 240V if you measure between the two "hot" legs.

Other kinds of 50 amp hookups that are usually used for home appliances or commercial/industrial applications *do* provide two phase hot legs and therefore will give you 240V.
I feel like I'm hammering your posts. My apologies, not trying to be difficult.

50 amp RV hookups are exactly the same as a 50 amp circuit receptacle in a residence. Two legs of a split phase circuit provide 240 volts. Because RVs don't use both sides of the single phase for 240 volts--apparently few if any RVs use 240 volt appliances--there is a misperseption.

A standard NEMA 14-50R is 240 volts no matter where you go.
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Old 08-10-2022, 08:49 AM   #20
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A standard NEMA 14-50R is 240 volts no matter where you go.
It's supposed to be. I've heard of shadier campgrounds where it's not. I wouldn't be surprised at all if there is some truth to that, as I've seen campgrounds do all sorts of things that are wrong according to the codes. One even so far as omitting ground wire and using the emt conduit instead.

I guess if you're worried about it, carry a meter and perform your due diligence.
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