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Old 12-29-2016, 08:02 AM   #1
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Help with electrical cord wiring

As we all know the large 50 amp cord is no fun to wrestle. Having some 8 gauge SO cord I thought I would make one easier to handle. My 5th wheel only has one AC so Ill never draw 50 amps.
I bought a 30 amp male and a 50 amp female to plug into the camper. Of course the green goes to ground and I figured the black and white went to here respective connections. When I tried it only half the camper has 110. Switch polarity on the plug and the other half works. There is the 4th connector in the plug which is red, should I be using it?

TIA
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Old 12-29-2016, 08:14 AM   #2
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Be careful here!

Others will soon be piling on but here's my take--

You have a 50 amp RV.
That means it's wired for TWO 50 amp hot wires and a neutral and a ground.

IF you put on a 30 amp plug you only have ONE 30 amp hot and so you
get the result you've seen.

Better to keep what you have and just wrestle the big cord IMO.

Again-- be CAREFUL out there!
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Old 12-29-2016, 08:29 AM   #3
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A 50 to 30 amp dogbone adapter does exactly what the OP is trying to accomplish.
Nothing harmful about it.

The OP will need to jumper the black pole to the red pole with a short piece of wire inside the 50 amp female plug. That way it will feed both sides.

wmtire has several really good wiring diagrams he typically posts on these kinds of querys.
I'm sure he'll be along and post them soon.
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Old 12-29-2016, 08:39 AM   #4
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Quote:
Originally Posted by ibboatin28 View Post
As we all know the large 50 amp cord is no fun to wrestle. Having some 8 gauge SO cord I thought I would make one easier to handle. My 5th wheel only has one AC so Ill never draw 50 amps.
I bought a 30 amp male and a 50 amp female to plug into the camper. Of course the green goes to ground and I figured the black and white went to here respective connections. When I tried it only half the camper has 110. Switch polarity on the plug and the other half works. There is the 4th connector in the plug which is red, should I be using it?

TIA
I would also be careful, since it appears you don't understand the difference between a 30 amp 120 volt RV and a 50 amp 120/240 volt split phase RV.

The 50 amp RV is fed by two 120 volt hot lines (the black is one and the red is the other), each with 50 amps per hot line for a total of 100 amps capability. (first pic below) It feeds your RV's electrical distribution panel (second pic below), that keeps each line separate with one hot line providing only 120 volt power to half the RV, and the other hot line providing only 120 volt power to the other half of the RV. This balances the load as best it can, and the neutral (white wire) is shared to carry load imbalance. Ground is the green.

This explains that:

https://www.rvtechmag.com/electrical/chapter3.php

To provide power to both sides, as in an adapter or the adaptive power cord, you are making...you must jump the 30 amps black wire over to the red second hot line...so that the one hot line on the 30 amp is providing power to both hot legs of the 50 amp (third pic below).

Here are some pics to help.










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Old 12-29-2016, 08:40 AM   #5
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Quote:
Originally Posted by 5picker View Post
A 50 to 30 amp dogbone adapter does exactly what the OP is trying to accomplish.
Nothing harmful about it.

The OP will need to jumper the black pole to the red pole with a short piece of wire inside the 50 amp female plug. That way it will feed both sides.

wmtire has several really good wiring diagrams he typically posts on these kinds of querys.
I'm sure he'll be along and post them soon.
LOL. I was doing it as you were posting. Too funny.
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Old 12-29-2016, 08:50 AM   #6
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Originally Posted by wmtire View Post
LOL. I was doing it as you were posting. Too funny.
I knew you'd be along.

And while I agree the OP seems to not have a good grasp of how their electrical system works (from the original comments) what they are trying to accomplish, it is something that is likely done somewhere in a campground every day, when using a 50 to 30 adapter.
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Old 12-29-2016, 08:57 AM   #7
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I'm just wondering- are there any 50 amp rigs out there that maybe have
240 v appliances??
I bet some park models do but I wonder if there are any over the road models that do?
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Old 12-29-2016, 09:00 AM   #8
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Originally Posted by wmtire View Post
I would also be careful, since it appears you don't understand the difference between a 30 amp 120 volt RV and a 50 amp 120/240 volt split phase RV.

The 50 amp RV is fed by two 120 volt hot lines (the black is one and the red is the other), each with 50 amps per hot line for a total of 100 amps capability. (first pic below) It feeds your RV's electrical distribution panel (second pic below), that keeps each line separate with one hot line providing only 120 volt power to half the RV, and the other hot line providing only 120 volt power to the other half of the RV. This balances the load as best it can, and the neutral (white wire) is shared to carry load imbalance. Ground is the green.

This explains that:

https://www.rvtechmag.com/electrical/chapter3.php

To provide power to both sides, as in an adapter or the adaptive power cord, you are making...you must jump the 30 amps black wire over to the red second hot line...so that the one hot line on the 30 amp is providing power to both hot legs of the 50 amp (third pic below).

Here are some pics to help.










The jumper wire is what I'm missing. I'll fix that!

Thanks all
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Old 12-29-2016, 09:29 AM   #9
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Originally Posted by KyDan View Post
I'm just wondering- are there any 50 amp rigs out there that maybe have
240 v appliances??
I bet some park models do but I wonder if there are any over the road models that do?
I have not ever seen any but that doesn't mean there isn't or that someone hasn't installed something.

There was talk a year or so ago about installing a 220v on-demand water heater in some units. I've yet to see any.
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Old 12-29-2016, 09:31 AM   #10
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The jumper wire is what I'm missing. I'll fix that!

Thanks all
You are welcome. Now just bear in mind (and using the RV's electrical panel diagram above as an example) that now since you are only going to using a 30 amp outlet to provide power..... instead of having 50 amps providing power to one side (L1 with four subcircuits) and a different 50 amps providing power to the other side (L2 with 6 subcircuits).... you are now sharing just 30 amps between all 10 subcircuits.

You will need to be selective as to what you have turned on (and what must be turned off) since you went from 100 total amps capability to 30 amps total capability.

It's more than just the second air conditioner. You most likely will overload if you try to run microwaves, space heaters, electric water heater element and other items, Or specific combinations of, when only on 30 amps.
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Old 12-29-2016, 06:23 PM   #11
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I bought a 30 amp power cord on amazon for about $56. It has a 30 amp male and a 50 amp female that plugs directly into my 5th wheel. Problem solved.
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Old 12-29-2016, 09:26 PM   #12
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I drilled a 3in hole in the side of a 5 gal bucket at the bottom.put ypur cord in the bucket with trailer end sticking out the hole from the inside.Leave as much as you need to hook up with bucket sitting on the ground.Then coil the rest carefully into the bucket til the end . The trailer end can then be looped over the top into bucket for storage.It still weighs the same but the python is in a cage.Works well for me.
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Old 12-30-2016, 06:11 PM   #13
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You can always buy a cable that never gets stiff, they are not cheap but they will stay flexible to forty below


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Old 12-31-2016, 09:14 AM   #14
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Also be aware that if you downsize the wire Guage that it is still being powered by a 50 amp breaker. That means that if you overload the cable it could fire before it pulled enough amperage to trip the breaker!
Breaker should always be sized based on the wire Guage, not the load on the circuit. You should not downsize the wire Guage if you don't have to. Us 30 amp guys do that anytime we use an adapter to connect to a 50 amp circuit. This means we are undersized from the pedestal to the 30 amp breaker in the travel trailer.
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Old 12-31-2016, 09:29 AM   #15
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This means we are undersized from the pedestal to the 30 amp breaker in the travel trailer.
Not so. All loads are after that 30 amp breaker and therefore the smaller gage wiring is protected.
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Old 12-31-2016, 09:54 AM   #16
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You can always buy a cable that never gets stiff, they are not cheap but they will stay flexible to forty below


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I purchased, unterminated, 25 feet of this cable and terminated the ends myself to make a jumper cable so I would not have to pull the supplied cable out. The Glendinning cable (50amp) is like a wet noodle, even in subzero temps. Only a couple times have I had to pull a couple feet of the supplied cable out when the extension wouldn't reach . Yes, not cheap but worth every penny. Just a thought.
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Old 12-31-2016, 04:33 PM   #17
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Not so. All loads are after that 30 amp breaker and therefore the smaller gage wiring is protected.
No, it is correct. The cable from the pedestal to the trailer is sized for 30 amp but is being fed by the 50 amp breaker. If it shorts out between the pedestal and trailer it could burn before tripping the 50 amp breaker. The loads INSIDE the trailer are protected by the trailers 30 amp breaker, as you have noted.
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Old 12-31-2016, 05:38 PM   #18
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No, it is correct. The cable from the pedestal to the trailer is sized for 30 amp but is being fed by the 50 amp breaker. If it shorts out between the pedestal and trailer it could burn before tripping the 50 amp breaker. The loads INSIDE the trailer are protected by the trailers 30 amp breaker, as you have noted.
Agree with the burn scenario but the 30 amp cable is protected by the 30 amp breaker in normal use. And in that scenario it is not undersized. If there is a short as you say the loads inside the trailer will not need protecting. Total load will be on the 50 amp breaker.
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Old 12-31-2016, 06:06 PM   #19
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No, it is correct. The cable from the pedestal to the trailer is sized for 30 amp but is being fed by the 50 amp breaker. If it shorts out between the pedestal and trailer it could burn before tripping the 50 amp breaker. The loads INSIDE the trailer are protected by the trailers 30 amp breaker, as you have noted.
The OP is not connecting to a 50 amp outlet. He is connecting to a 30 amp outlet at the campground pedestal, and building an adapter cord to allow him to connect his 50 amp RV to a 30 amp outlet on the pedestal. He is only going to have 30 amps total from the pedestal, thru his power cord, and thru his RV.

That was his problem with only having power to half his RV until he installed the jumper wire from L1 over onto L2.

The problem you would be advising on, is when someone connects a 30 amp RV and cord to a 50 amp outlet...which is not the case here.
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Old 12-31-2016, 06:17 PM   #20
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I didn't read the OP that way. I read that he wanted a lighter cord to connect his rig to 50 amp pedestal. Glad he got it working, that is what matters. This is always a confusing subject.
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