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15/30/50 SHORE POWER PLUG IN ?

Oasisbob
Explorer
Explorer
My camper, listed below, uses what I believe is, a 30 amp shore power plug. I have a 15 amp adaptor. That is the standard looking plug in right? Am I correct in thinking a 50 amp connector is 220 volts? So is there an adaptor that allows me to plug into a 50 amp box using only one side? I ask as I am using a friends property and he has only 50 amp plug. It's kind of confusing atleast to me. Thanks
Oasis Bob
Wonderful wife 3 of 4 kids at home. 1 proudly serving in USAF
2018 Ford Explorer
2001 Bantam Trail Lite B-19

HAPPY TRAILS:)
48 REPLIES 48

fj12ryder
Explorer III
Explorer III
PNW_Steve wrote:
rk911 wrote:
fj12ryder wrote:
Just get a 50 amp to 30 amp adapter. You plug your 50 amp plug into it and then into the 30 amp pedestal. Easy peasy.

and no, a 50-amp RV pedestal is not 220-volts. it is two separate legs of 120-volts, each leg capable of supplying 50-amps. you can safely connect your 30-amp RV to the 50-amp RV pedestal using the 30-female/50-male dogbone adapter


Thank you for enlightening us.

It's a wonder I passed the Journeyman's electrician's test given that I always thought that a 50amp 240volt circuit actually provided 240 volts.

Learn something new everyday ๐Ÿ™‚
I guess we should all be glad you're not wiring up RV park pedestals.
Howard and Peggy

"Don't Panic"

rk911
Explorer
Explorer
2oldman wrote:
Oasisbob wrote:
So can a 50 amp outlet be 110 volt or are they, or can they be 220 volt? How do you tell?
My choice would be a voltmeter.

yup. I test each pedestal before I connect. my tester shows the voltage and proper wiring (proper ground, neutral, etc.) for each leg...~115 to 120-volts.

Rich
Ham Radio, Sport Pilot, Retired 9-1-1 Call Center Administrator
_________________________________
2016 Itasca Suncruiser 38Q
'46 Willys CJ2A
'23 Jeep Wrangler JL
'10 Jeep Liberty KK

& MaggieThe Wonder Beagle

2oldman
Explorer II
Explorer II
Oasisbob wrote:
So can a 50 amp outlet be 110 volt or are they, or can they be 220 volt? How do you tell?
My choice would be a voltmeter.
"If I'm wearing long pants, I'm too far north" - 2oldman

PNW_Steve
Explorer
Explorer
rk911 wrote:
fj12ryder wrote:
Just get a 50 amp to 30 amp adapter. You plug your 50 amp plug into it and then into the 30 amp pedestal. Easy peasy.

and no, a 50-amp RV pedestal is not 220-volts. it is two separate legs of 120-volts, each leg capable of supplying 50-amps. you can safely connect your 30-amp RV to the 50-amp RV pedestal using the 30-female/50-male dogbone adapter


Thank you for enlightening us.

It's a wonder I passed the Journeyman's electrician's test given that I always thought that a 50amp 240volt circuit actually provided 240 volts.

Learn something new everyday ๐Ÿ™‚
2004.5 Dodge 3500 5.9 Cummins, NV5400, 5" turbo back stainless exhaust, Edger programmer & 22.5 Alcoa's
2002 Forest River 36 5th Wheel (staying home)
1992 Jayco 29 5th Wheel (Mexico veteran & headed back)
2002 "faux" Wanderlodge 40' My new toy....

sparkydave
Explorer
Explorer
stevenal wrote:


Sparkydave,

My profession as well, registered in the state I reside in. I won't be stamping the design proposed. In your appliance example, you are plugging your UL listed #18 wire device into a NEMA 5-15 or 5-20 receptacle without an adapter, else you would be violating its listing.

https://rvnerds.com/2017/06/12/power-adapter-101/


True, it's not really up to code, but do the math. Shore power cord "burning up"? Horrors! Pardon me, but that sounds a little like worrying about the fire department getting your carpets wet if your house is on fire.

These seemingly unlikely faults that somehow draw exactly 50 amps and happen to occur between the dogbone and the circuit breakers must be a genuine concern and cause shore power cords to burn up all the time. I should get rid of my 50 amp to 30 amp dogbone right away, because if I'm plugged into a 50 amp pedestal with my 30 amp RV, I can't be violating UL and have my shore power cord rating possibly being exceeded while my RV is burning to the ground.:R Circuit breakers can and do fail, so plugging a 30 amp into a 30 amp pedestal must be dangerous too. If these faults that can cause a 50 amp fault to happen between the pedestal and the breakers, then it must be equally likely you could have a 30 amp fault in the same place while plugged into a 30 amp pedestal, but we can breathe easy because we won't be exceeding the shore power cord rating and having it "burn up". The RV will only have a 3560 watt problem inside it instead a 5900 watt problem, so the fire in the RV won't be as big :B

Now do you see what I'm getting at? Focusing on a minor issue instead of the much bigger issue in an unlikely occurrence.

Nah, I think I'll worry more about the condition of the wires and the outlets in the pedestal. I'd also worry more about the chuckleheads who wire RVs such as mine; I had all the ground wires from the 12 volt side jammed under one wire nut. Even the rat's nest of electrical tape couldn't hold it together.

wa8yxm
Explorer III
Explorer III
Your understanding of 50 amps is a bit shakey. It is 50 amps at 240 divided
Basically think of this

1--120 volts - N - 120 volts--2

Now from 1 to n is 120 volts.. likewise n to 2 is 120 volts 1-2 is 240

SO. you can (and should) get a 30-50 "Dogbone" Adapter (30 amp outlet. 50 amp plug short cord between 'em) at your favorite RV supply or Wally World. (Wal*mart though I don't like shopping there if I can help it).

It handles all the differences for you.. IT connects to just ONE leg and neutral so you get 120 volt (At up to 50 amp) but your 30 amp breaker in the RV limits the current.
Home was where I park it. but alas the.
2005 Damon Intruder 377 Alas declared a total loss
after a semi "nicked" it. Still have the radios
Kenwood TS-2000, ICOM ID-5100, ID-51A+2, ID-880 REF030C most times

westernrvparkow
Explorer
Explorer
llr wrote:
Oasisbob wrote:
So can a 50 amp outlet be 110 volt or are they, or can they be 220 volt? How do you tell?


They are 220, across the 2 hots, the 50-30 adapter only uses 1 hot so no issue
Other than the fact the voltage is actually 240 volts AC, this is the correct answer. There is no such thing in residential wiring where a single wire carries 240 volts. All 240 volt outlets are as described, two separate 120 volt lines, out of phase that measure 240 volts AC between them. Measuring between either hot line to either the ground or the neutral the voltage will result in 120 volts AC. Harbor Freight sells volt meters for less than $10.00. They are extremely easy to use. Using one is the best tool and easiest way to confirm a questionable outlet is properly wired.

stevenal
Nomad II
Nomad II
Sandia Man wrote:
No circuit breaker required on adapters as your RV has a main breaker that will instantly open upon reaching its rated value
.

Not true, the breaker will pass rated current all day without tripping. It will enter an inverse time-current curve at about 125% of rating. Instantaneous tripping will occur once you get to 3 to 10X rating. Any breaker will only protect for faults and overloads downstream.

Sparkydave,

My profession as well, registered in the state I reside in. I won't be stamping the design proposed. In your appliance example, you are plugging your UL listed #18 wire device into a NEMA 5-15 or 5-20 receptacle without an adapter, else you would be violating its listing.

https://rvnerds.com/2017/06/12/power-adapter-101/
'18 Bigfoot 1500 Torklifts and Fastguns
'17 F350 Powerstroke Supercab SRW LB 4X4

rk911
Explorer
Explorer
fj12ryder wrote:
Just get a 50 amp to 30 amp adapter. You plug your 50 amp plug into it and then into the 30 amp pedestal. Easy peasy.

and no, a 50-amp RV pedestal is not 220-volts. it is two separate legs of 120-volts, each leg capable of supplying 50-amps. you can safely connect your 30-amp RV to the 50-amp RV pedestal using the 30-female/50-male dogbone adapter
Rich
Ham Radio, Sport Pilot, Retired 9-1-1 Call Center Administrator
_________________________________
2016 Itasca Suncruiser 38Q
'46 Willys CJ2A
'23 Jeep Wrangler JL
'10 Jeep Liberty KK

& MaggieThe Wonder Beagle

llr
Explorer
Explorer
Oasisbob wrote:
So can a 50 amp outlet be 110 volt or are they, or can they be 220 volt? How do you tell?


They are 220, across the 2 hots, the 50-30 adapter only uses 1 hot so no issue

Oasisbob
Explorer
Explorer
So can a 50 amp outlet be 110 volt or are they, or can they be 220 volt? How do you tell?
Oasis Bob
Wonderful wife 3 of 4 kids at home. 1 proudly serving in USAF
2018 Ford Explorer
2001 Bantam Trail Lite B-19

HAPPY TRAILS:)

Roger10378
Explorer II
Explorer II
Dutchman is confused. If your friend has a 4 wire 220 plug that is exactly what you need. It is when people try plugging a 30 amp RV plug into a 220V 3 wire that gets them in trouble. Just remember that you are limited to the smaller of the 2 breakers as your friends plug could be anywhere from 30 to 60 amps.
2005 Cardinal 30TS
2007 Chevy 2500HD D/A

Sandia_Man
Explorer II
Explorer II
Head on over to your local wallyworld, they have a variety of adapters to handle any scenario. No circuit breaker required on adapters as your RV has a main breaker that will instantly open upon reaching its rated value. We use our 50 amp adapter often for our 30 amp rig since many power pedestals at older parks have very worn 30 amp receptacles.

DutchmenSport
Explorer
Explorer
If your friend has a 50 amp 220 plug, don't use it. Chances are, the 50 to 30 amp RV adapter won't plug in anyway. More than likely, the 50 amp 220 plug was set up for a welder, at best a cloths dryer, or an electric oven .... all of which have different plugs form each other.

You would be better off plugging your 30 amp camper into a 20 amp (110 volt) household plug with an RV step up adapter (20 to 30 amp). Your camper will still only have a max of 20 amps, but at least you won't blow up your wiring and electronics by plugging into a 220 volt power source.

50 amp RVs use two legs of 110 volts, each rated at 50 amp. It is not 220. Your camper manages each leg so the overall usage in the entire camper never exceeds 50 amps. But it's still only 110 volts.

My suggestion to be safe, plug into a 15-20 amp (110 volt) household plug with the RV adapter, either the "puck" or a "dogbone" adapter, and manage the power inside your camper so you won't pop the electric box breaker. Remember, if plugging into a 15 or 20 amp house hold electric socket, everything on the line uses part of that 15 or 20 amp; for example, lights inside the house, or appliances plugged into the same line. This reduces the available amp draw you can use inside your camper without popping a breaker switch.

sparkydave
Explorer
Explorer
stevenal wrote:
These "adapters" don't seem to include circuit breakers. Your camper wiring and cord ahead of the camper's distribution panel is designed for use on a 30 A circuit protected with a 30 A breaker. The 50 A circuit will allow the wiring to overload and possibly catch fire. Are these things UL listed?

Note that going the other way is not a problem, since 15 and 20 A breakers will protect the 30 A rated circuit. Doesn't your friend have a 15 A receptacle?


Ah yes, the old "your 30 amp shore power cord could burn up if you use a 50 amp to 30 amp adapter". I did the calculations and a write up a while back on why the probability of that happening is non existent. I'm an electrical engineer. If you get a short circuit (most likely failure), then the 50 amp breaker will trip quickly. If you happen to get some fault that somehow takes in excess of 30 amps but less than 50 amps before your 30 amp breaker (extremely unlikely), then the cord will be dissipating about 100 watts. Not good, but won't necessarily burn up as much as getting warm. However, the other 5900 watts (at 50 amps) will definitely be making whatever is causing the fault to get very hot very quickly.

An analogy: If you plug an appliance with an 18 AWG cord into a 20 amp outlet in your home, the cord is not rated for 20 amps, but the cord is not going to be the thing burning up if the appliance malfunctioned. Why? Because again, short circuits are far more likely and they will trip the breaker quickly. Even if it was an very unlikely partial failure that somehow took just under 20 amps, once again, the malfunctioning appliance would be catching on fire long before the cord.