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Author Topic: 50 amp to rv 30 amp  (Read 4403 times)

galangmaid

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50 amp to rv 30 amp
« on: July 25, 2010, 12:17:06 PM »
How can one adapt from an older NEMA 10-50R receptacle to a RV NEMA TT-30m shore power plug?

Thanks,
Gary
Gary

Ned

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Re: 50 amp to rv 30 amp
« Reply #1 on: July 25, 2010, 01:03:39 PM »
You can buy an adapter that connects one leg of the 50A outlet to a 30A female connector.
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

galangmaid

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Re: 50 amp to rv 30 amp
« Reply #2 on: July 25, 2010, 01:11:21 PM »
Hi Ned,
That what I was hoping to find an adaptor but I've been looking on the internet for the last 3- 4 hours and can not find one.  Do you happen to know where to find one?

Thanks,
Gary
Gary

Gary RV_Wizard

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Re: 50 amp to rv 30 amp
« Reply #3 on: July 25, 2010, 01:11:53 PM »
You will probably have to make the adapter. RV suppliers don't make one for the uncommon 10-50R outlet and industrial suppliers don't make 10-50R adapters for 30A RV plugs. 

Mount a 30A RV outlet in a waterproof box and wire a 10-50P plug to it with (at least) 10 gauge cable. Either of the slanted terminals carries 125V and the vertical terminal is the neutral.

The drawback is there is no ground on a 10-50R, so you have no way to ground the RV. That's a safety issue. If you have access to the outlet box, you could jury rig the ground on the trailer plug to make direct contact with the outlet box, which should be grounded if installed per electrical code. That probably makes the adapter a semi-permanent part of the outlet (requires a screw driver or some such to remove it). Some creativity will be required if you want the adapter to be easily removable..
« Last Edit: July 25, 2010, 01:18:47 PM by RV Roamer »
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

Ned

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Re: 50 amp to rv 30 amp
« Reply #4 on: July 25, 2010, 01:18:44 PM »
Gary is right, I read 10-50R and thought 14-50R, the most common outlet.  Be sure you wire the adapter for the 120V pins and not the 240V pins.
« Last Edit: July 25, 2010, 01:21:09 PM by Ned »
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

Gary RV_Wizard

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Re: 50 amp to rv 30 amp
« Reply #5 on: July 25, 2010, 01:20:15 PM »
The 10-50R is a 240v outlet, with 240 between the two hots and 120 between either hot and neutral. It's the old style outlet for an electric range. The outlet has a ground strap that connects to the physical box it is in, but no ground terminal on the outlet itself.
Gary
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Gary Brinck
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Home: Ocala National Forest, FL

Ned

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Re: 50 amp to rv 30 amp
« Reply #6 on: July 25, 2010, 01:26:42 PM »
Yep, I looked it up :)
-- Ned -- Fulltimer 1997-2013
1997 Holiday Rambler Endeavor LE
2007 GMC Canyon

galangmaid

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Re: 50 amp to rv 30 amp
« Reply #7 on: July 25, 2010, 01:31:58 PM »
Thanks Guys.
Maybe I can find a NEMA 10-50  to a NEMA 14-50R adaptor then I would use my campground 50 to 30 adaptor on it for my shore power cord.

Gary

vermilye

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Re: 50 amp to rv 30 amp
« Reply #8 on: July 25, 2010, 01:59:51 PM »
Although it was questionably OK to run a range or dryer on a combined ground/neutral, since 1996 it has not been code & 3 wire with separate ground connections have been required.  They have always been required for RVs - Please do not try to use a 10-50 connector to power an RV. It will split the ground & neutral current from the receptacle back to the service entrance panel, making any grounds along the way hot.  This could include plumbing, metal receptacle boxes, duct work, etc.

Gary RV_Wizard

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Re: 50 amp to rv 30 amp
« Reply #9 on: July 25, 2010, 03:11:41 PM »
You won't find a 14-50 to 10-50 adapter because the 14-50R has a separate ground terminal  that cannot be matched up to the 10-50.

As Vermilye says, this is not a good idea.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

galangmaid

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Re: 50 amp to rv 30 amp
« Reply #10 on: July 25, 2010, 05:26:21 PM »
I guess I could wire it for a 14-50r. and add a ground wire between it and the panel.
Right now it's use for a welder in my friend shop which she doesn't use anymore. The panel box is right there above it. Right now I'm connected to a 20 amp home outlet but that's not enough juice to run my one A/C.  I usally run my Kohler 7kw generator for the two  A/C every week and with 105 deg. temp around here in the Atlanta area I want to keep the RV cooler. At least my genny is getting exercise.
Thanks a lot for all your help. 
Gary

Alaskansnowbirds

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Re: 50 amp to rv 30 amp
« Reply #11 on: July 25, 2010, 08:34:33 PM »
.....Right now it's use for a welder in my friend shop which she doesn't use anymore.

Could you just replace the receptacle that is there now with a 10-50R? Are there enough wires in the box to do that?

Quote
The panel box is right there above it.

If you can't replace the receptacle can you just mount a new box?
Don & Peg
Alaska/Arizona
Currently located here.
Weather at Camp Verde, AZ.

Jammer

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Re: 50 amp to rv 30 amp
« Reply #12 on: July 25, 2010, 08:57:18 PM »
Historically the 10-50R outlet was considered the high-falutin way to wire a 50a 240 volt circuit because the neutral was full size, and grounds to individual outlets in those days were much smaller than the current-carrying conductors.  If the outlet is fed directly from the service entrance panel (which is after all the most common situation) then the neutral wire goes to the same bus the ground wire would, and the two are effectively interchangeable.  In those days, the full-sized neutral was thought to be better than the smaller ground, and so people put in 10-50R outlets for things like welders and other 240v 50a loads.

I would suggest that you have a qualified electrician rewire the outlet for 30A 120V with ground and install a suitable outlet.  There are enough conductors to do that and provided they are clearly marked and the breaker or fuse is changed there should be no safety-related reason not to do so.

Otherwise, as others have noted above, grounding is problematic and poses a safety hazard.
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1997 K2500 regular cab long bed pickup / 1971 Cayo C-11

Gary RV_Wizard

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Re: 50 amp to rv 30 amp
« Reply #13 on: July 25, 2010, 09:07:31 PM »
Since the 10-50R is no longer needed and the breaker panel is readily accessible, replacing it with a 14-50R and a suitable ground wire is the best solution by far.
Gary
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Gary Brinck
Summers: Black Mountain, NC
Home: Ocala National Forest, FL

 

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