50 amp 220 male to 30 amp 110 twist lock female plug

[hphock]

I was hoping to find a 25 foot cord to go from a 50 amp wall box to my 30 amp RV.  I see dog bones galore but why is there no 25' cable so I don't need the dogbone?  If I were to make one, how might I wire it since the 50 amp has 2 hot, a ground and a neutral and the 30 amp has ground, neutral and only 1 hot wire? 

I ask as we have an a 50 amp box where our hot tub used to be and its only 20 feet from where we park the RV.  

[richard5933]

First, welcome to the FMCA forum. Glad to have you here.

Be careful doing this - it's possible to successfully do what you want, but it's also possible to fry your coach's electrical system.

A 30-amp RV is running a 120v system. As you said, one hot, one neutral, and a ground. Your hot tub receptacle has two hots, a neutral, and a ground. Their typically wired for 240v, and it's not always just plug-n-play to plug an RV adapter into it. It's possible to pull 240v out of that box if you're not careful.

My suggestion would be to first replace the receptacle in the hot tub wall box with a properly wired RV receptacle box with both 30-amp and 50-amp receptacles. You can buy them at HD and Lowes. Once you have that, then you can just plug in your 30-amp cord. Should not cost all that much to get the supplies, and even if you have an electrician do the work it should take only an hour or so.

It's also possible to just replace the hot tub receptacle with a properly wired 50-amp RV receptacle and then plug in your 30-amp cord using an adapter. The danger of using an adapter to plug the 30-amp cord into the 50-amp receptacle is that you have a breaker with a higher rating than the 30-amp cord can carry. That means that if you overload the circuit, the cord can overheat and have a catastrophic failure before the 50-amp breaker ever knows there's a problem.

[kaypsmith]

As Richard suggest one of the CG style boxes would be great,. Does the 50 amp box have a female plug already or must you straight wire to the box and if so what style plug is attached to the box? The RV is already set up for 30 amps so the cord from RV to plug in should be fine as long as you plug nothing else into that cord. If you choose to use only a 30 amp RV receptacle then while wiring the recep into the box, only attach the hot leg to either L1 or L2, then neutral to neutral bus bar, and ground to the ground bus bar. If the 50 amp box is properly wired the ground bus bar is isolated from the neutral, if it is not then you need it rewired anyway.

Edited August 11, 2020 by kaypsmith

[tlstory]

5 hours ago, hphock said:

I was hoping to find a 25 foot cord to go from a 50 amp wall box to my 30 amp RV.  I see dog bones galore but why is there no 25' cable so I don't need the dogbone?  If I were to make one, how might I wire it since the 50 amp has 2 hot, a ground and a neutral and the 30 amp has ground, neutral and only 1 hot wire? 

I ask as we have an a 50 amp box where our hot tub used to be and its only 20 feet from where we park the RV.  

If you no longer plan to have or use a hot tub, I would just replace the breaker that supplies one of the legs of the 50 amp service with a 30 amp breaker and also replace the receptacle with a 30 amp RV receptacle that you can get most anywhere, and then you can just plug your coach into that receptacle without having to concern yourself over an electrical problem. That 50 amp receptacle is two legs of 25 amps each and they total 50 amps so that a coach, (or a hot tub), can use both of those legs to get whatever power they need to supply the high current needed in a 50 amp coach. That 50 amps is a conventional voltage and current source that can be used by coaches and households. A 30 amp coach receptacle is more commonly used in coaches that are equipped for it, as yours is, and if you use just one leg of the 50 amp service that is currently provided to the "hot tub", and replace the breaker with a 120v/30amp breaker, and then wire the receptacle using that line, while tying off the other line, (pull the breaker for the other leg), you will have one 120v/30amp leg, one neutral line, and one ground line, and you are go to go without risking any electrical error that would damage your coaches electrical system. If you want to leave the 50 amp service in place, you could also do that by pulling a new line from the breaker box to the receptacle box and adding a 30 amp receptacle in that box and a 30 amp breaker in the supply box and that would then give both the 50 amp and 30 amp connections in the same receptacle box, which may also need to be changed in that case. Best of luck, and if you are not familiar with electrical codes and methods of installing that kind of thing, I would heartily recommend asking an electrician to help you out with that chore. 

[richard5933]

A properly wired 50-amp RV receptacle will have two 50-amp breakers supplying it with power (not 25-amp). Each leg of the 50-amp receptacle provide up to 50-amps @ 120v, and combined can provide 240v.

If you are unsure of how things work please have someone that does assist.

[kaypsmith]

5 hours ago, tlstory said:

That 50 amp receptacle is two legs of 25 amps each and they total 50 amps

This part of your statement is incorrect, a 50 amp breaker @240 volts is 50 amps twice, one for each leg @ 120 volts each, therefore if you count the current, a 50 amp times two = 100 amps @ 120 volts. Just backing you up Richard.

[wayne77590]

See if this would work for you 50 to 30 amp adapter

They call it a 30 to 50.

This is NOT a dog bone adapter.

I would definitely have a surge guard in-line, like the EMS-PT50C or similar.

Edited August 11, 2020 by wayne77590

[richard5933]

50 minutes ago, wayne77590 said:

See if this would work for you 50 to 30 amp adapter

They call it a 30 to 50.

This is NOT a dog bone adapter.

Those will work with a properly-wired RV 50-amp receptacle, but they leave your cordset unprotected. Using an adapter like this means plugging a cord rated at 30 amps into a receptacle protected by a 50-amp breaker. Those extra 20 amps can do quite a bit of damage before the breaker does it's job.

[manholt]

hphock.  Welcome!

MHO, go with Kay S., or Wayne!  Both good, sound, advice!

[kaypsmith]

22 hours ago, hphock said:

I was hoping to find a 25 foot cord to go from a 50 amp wall box to my 30 amp RV.  I see dog bones galore but why is there no 25' cable so I don't need the dogbone?  If I were to make one, how might I wire it since the 50 amp has 2 hot, a ground and a neutral and the 30 amp has ground, neutral and only 1 hot wire? 

I ask as we have an a 50 amp box where our hot tub used to be and its only 20 feet from where we park the RV.  

Well to give a short answer to your question, you can could acquire a 25 foot 6/3 or 6/2/ with 8 gauge ground wire, then add the correct female plug to one end (correctly wired), making sure that hot is to the correct location, neutral to correct location, and ground (green) to ground on the receptical. Now wire directly into the 50 amp box with the other end,  you can attach the hot lead to either L1 or L2, both of these are only 120 +/-, then neutral to the neutral bus bar, and ground to the ground bus bar. 

[rayin]

This is not a DIY project for most people. In a "dogbone" 30 to 50 adapter one leg of 120VAC(30A)is wired to both hot legs of your(50A) RV.

 

[kaypsmith]

16 hours ago, RayIN said:

This is not a DIY project for most people. In a "dogbone" 30 to 50 adapter one leg of 120VAC(30A)is wired to both hot legs of your(50A) RV.

 

Ray what you say is true, but the OP is going from 50 to 30 not the other way, 50 amp to 30 amp, legs not tied together.

 30 to 50, legs tied together, to be like a 50 amp, only 120 in phase with each other, assimilated 240, you can't run a 240 appliance, unlike true 240 volt, each leg out of phase, you can run a 240 volt appliance

On 8/10/2020 at 8:09 PM, hphock said:

If I were to make one, how might I wire it since the 50 amp has 2 hot, a ground and a neutral and the 30 amp has ground, neutral and only 1 hot wire? 

.     The Op has a 30 amp RV, not a 50 amp. Above is the OP's question.

[rayin]

Thanks for the catch KaySmith.

Although what I said is accurate, it is reversed from what hphock wants to accomplish.  It will be simpler and much easier for hphock to buy a 30A RV extension cord and replace the 30A male plug with a 50A male plug. Of course the 30A RV extension cord only has 3 wires,  the black wire connects to one hot leg in the 50A male plug, the other two connect the same as a 30A male plug. Your total ampere limit will be 3,600 watts instead of 12,000 watts on 50A service.

The only  issue is, now your 30A entrance cord is wired to a 50A pedestal breaker, just like when using a store-bought 50A to 30A dogbone adapter.

 

 

[kaypsmith]

36 minutes ago, RayIN said:

The only  issue is, now your 30A entrance cord is wired to a 50A pedestal breaker, just like when using a store-bought 50A to 30A dogbone adapter.

This is why I suggested using 6 gauge wire, it will satisfy the concern about the wire being too small for 50 amp, and the RV is already 30 amp and will only have a 30 amp main breaker to take care of the RV. And yes those dogbones are sold for their purpose and used many times without incident, if they were a problem, the manufacturers would be sued and production would cease.

Here is one more remedy for you, use a CG style 50 amp shore power box and use this adapter. https://www.amazon.com/Plugrand-14-50P-Locking-Adapter，RV-Adapter/dp/B07RBTLVMH/ref=pd_lpo_23_img_2/137-4996575-8551336?_encoding=UTF8&pd_rd_i=B07RBTLVMH&pd_rd_r=f3067a3

Edited August 13, 2020 by kaypsmith

[richard5933]

Lots of great suggestions made to the OP. Probably time for them to chime in and let us know which way they want to go so we can focus on that and help them further rather than going in circles.

[hphock]

On 8/11/2020 at 12:45 PM, wayne77590 said:

See if this would work for you 50 to 30 amp adapter

They call it a 30 to 50.

This is NOT a dog bone adapter.

I would definitely have a surge guard in-line, like the EMS-PT50C or similar.

What is the difference between the adapter above and this: https://smile.amazon.com/gp/product/B07C8C33YV/ref=crt_ewc_img_dp_2?ie=UTF8&psc=1&smid=APF2F3A4Z2HBN  

[hphock]

I'll get a pic of the outlet.  I like the idea of reconfiguring a 30 AMP cable with a 50 amp male plug, using one HOT, Neutral and ground.  Could I pull the tooth of the HOT not in use?  The cable would stay at home and be wound up sorta like a garden hose on the wall when not in use and not plugged in to the outlet.  

What we want is to be able to run the fridge a few days prior to get it cool, keep the coach batteries charged, and in the summer, run the AC on low to keep the humidity down.  

 

[richard5933]

45 minutes ago, hphock said:

What is the difference between the adapter above and this: https://smile.amazon.com/gp/product/B07C8C33YV/ref=crt_ewc_img_dp_2?ie=UTF8&psc=1&smid=APF2F3A4Z2HBN  

Functionally the same. Which to choose depends on the particulars of the application. I like the adapters without the cable between the ends, and they tend to be durable. However, they also make the cord stand out far from the outlet and can encourage the weight of the cord to pull it from the outlet. When I use the short adapters I will bungee the whole works to the pedestal to make sure things don't pull out over time.

[richard5933]

22 minutes ago, hphock said:

I'll get a pic of the outlet.  I like the idea of reconfiguring a 30 AMP cable with a 50 amp male plug, using one HOT, Neutral and ground.  Could I pull the tooth of the HOT not in use?  The cable would stay at home and be wound up sorta like a garden hose on the wall when not in use and not plugged in to the outlet.  

What we want is to be able to run the fridge a few days prior to get it cool, keep the coach batteries charged, and in the summer, run the AC on low to keep the humidity down.  

 

Making a cord like that would work as long as you get the conductors attached to the proper terminals. Leaving the extra terminal in place will help the plug stay put in the socket better and make it less likely to pull out - I'd just leave it in place. It will do nothing since it won't be connected on the inside of the plug.

Depending on the gauge wire you use though, it might be possible to have a cord plugged into a breaker which has a higher rating than the cord. You can either change the breaker to a double 30-amp breaker to prevent any problems, or you can use the proper gauge wire for the 50-amp breaker. Probably cheaper to swap the breaker, and the 30-amp cord will be much easier to handle.

If you make the cord this way, it will be a good idea to permanently mark it at both ends somehow. After a few years you'll likely have a stack of cords & adapters, and it will always be possible to pull the wrong cord from the stack if not marked.

[wildebill308]

hphock, I have read through this mess twice now. STOP YOU CAN'T PLUG INTO THE OLD HOT TUBE POWER RECEPTACLE. All you have is a potential power source. 

Instead of all the weird extension cords and multiple adapters just run some appropriate cable from the power  supply (the old hot tub) to where you park your RV. Install this pedestal so you can plug your RV directly into it. Yes get the one with a 50 amp plug so when you upgrade your RV you won't have to do it over.

https://www.amazon.com/TL137US-Temporary-Receptacle-Installed-Unmetered/dp/B00A8FQUYW/ref=sr_1_1?crid=28UVFPNP6Q2JS&dchild=1&keywords=rv+power+pedestal+50+30+20&qid=1597332028&sprefix=RV+power+ped%2Caps%2C207&sr=8-1

Bill

[hermanmullins]

I made a extension cord out of 12 gauge power cord. Put a standard  three prong plug on one end and a 30 amp RV receptacle on the other end. I use a 50 to 30 amp reducer. I only use it to keep the refrigerator running and the inverter on. If hphock made such a extension card, with out the reducer,  he would have the length he needs and can hook it into any 20 amp wall plug. No worrying about going into the hot tube wiring.

Herman

[hphock]

1 hour ago, WILDEBILL308 said:

hphock, I have read through this mess twice now. STOP YOU CAN'T PLUG INTO THE OLD HOT TUBE POWER RECEPTACLE. All you have is a potential power source. 

Instead of all the weird extension cords and multiple adapters just run some appropriate cable from the power  supply (the old hot tub) to where you park your RV. Install this pedestal so you can plug your RV directly into it. Yes get the one with a 50 amp plug so when you upgrade your RV you won't have to do it over.

https://www.amazon.com/TL137US-Temporary-Receptacle-Installed-Unmetered/dp/B00A8FQUYW/ref=sr_1_1?crid=28UVFPNP6Q2JS&dchild=1&keywords=rv+power+pedestal+50+30+20&qid=1597332028&sprefix=RV+power+ped%2Caps%2C207&sr=8-1

Bill

I wasn't very clear.  The exterior box was previously wired for 50 amps from our breaker box.  An electrician put in a Home Depot 50 AMP RV outlet since it was already wired for 50 amps from the hot tub.  

[wildebill308]

Ok, but I still think the best practise is just what I said. Instead of all the weird extension cords and multiple adapters just run some appropriate cable from the power  supply (the old hot tub) to where you park your RV. Install this pedestal so you can plug your RV directly into it using the power cord from the RV. Yes get the one with a 50 amp plug so when you upgrade your RV you won't have to do it over. The only addition would be  a  appropriate power switch so you can turn power off when plugging in or unplugging. This reduces wear on the circuit breakers.

Bill

[richard5933]

If you have an RV 50-amp receptacle like in the photo above, simplest way is to just use an adapter.

Best way would be to have the pedestal box swapped out for one with both the 30-amp and 50-amp receptacles on it.

Also would work to make the cable you're talking about.

[kaypsmith]

In your case, I would simply either use a 50 to 30 dogbone, or the 50 to 30 adapter, plug your existing RV cable into it and forget it, much cheaper and less mess.