50 amp versus 100 amp

[schrod]

I am not super electrical savvy but I can wire 120 and 240 volt circuits. I am stymied though as to why 5th wheels are said to have a 50 amp hookup. Shouldn't it be called 100 amp hookup since they are using two 50 amp 120 volt circuits? Also why are travel trailers only on 30 amp hookup if they can use an adapter to go from the 50 down to the 30? Aren't the travel trailers really still on a single 50 amp circuit (when using the adapter) since they are on a 50 amp breaker at the standup? TIA

[easdsa]

Good questions. I can't answer why it is called a 50A, when it was called 100A when the exact same setup was used in the older S&B.

Those rigs that have only 30A service can use an adapter to use the 50A outlet, yes, but they are still limited to only 30A draw since the main 30A breaker in the rig will trip as soon as the load goes over 30A. Most of the time, though, the campsite pedestal will have 50A, 30A, and 20A outlets, so you will plug into the proper one without using any adapter. Of course, if the pedestal doesn't have a 50A outlet (like many State campgrounds) then those of us who have 50A coaches will have to use adapters and plug into the 30A outlet. That means that we only have 30 amps available to us.

[mike1poles]

Simple, only wire size determines amperage. True, on a 50A RV service, it has 2-50A circuits making it a total of 100 Amps. #6 wire is used and with a 4 wire, 25' power cable it is good for 60A, hence using 50A main in an RV. They make it 50A because many people add another 25' 4 wire #6 extension cable. For every so many feet, there is voltage loss and amperage increases. For the 30A, again it is wire size that determines how it is rated. There is not a 30A female to a 50A male adapter available to buy, only if someone buys separate parts and makes it themselves. But there is a 30A male to 50A female adapter available. It can be plugged into a 30A outlet in the pedestal, which splits into both circuits in the 50A RV, but you still only have 30 Amps total, because of the wire/breaker size in the pedestal.
As far as wiring something 240V in an RV, the standard RV 120V electric panel is made up horizontally, with the main 2 pole 50A breaker in the center of the panel, feeding one branch to the left and the other to the right, both 120V. In a house, the electric panel is made vertically, with the 2 pole main breaker feeding two branches that actually alternate in the panel with 120V on each branch, hence you can use a 2 pole breaker to get 240V. One of the considerations the RV industry has is in campgrounds the use only 120V service pedestals. Some do not have 240V service, some large campgrounds use what is called a wye secondary, which has 3 circuits of 120V and between the 120V legs the voltage is around 208V, not 240V. That voltage configuration, is used in businesses that have a large 120V load, but also have three phase A/C unit wired for the 208 Voltage, etc.
In our 5th wheel, I have changed out the RV type of panel to a square D, but I still only use a 50A main. Again, wire size determines that. The main reason I did it, was to add more circuits and split up what was in it, also added more outlets, for curling iron, blow dryer, etc, LOL , when momma's happy, everybody happy!!!!

Let me add one more thing, if you do not understand or know the basic principles of electricity, do not change or do anything. Have a license electrician come and talk with you and do the work. On that same note, I would not let a "dealers service center" touch a thing either. Some "techs" do have very "basic" knowledge of electricity, but that is all.

Hope this helps and God bless,
Mike

[Rockwood27]

Originally Posted by mike1poles

...As far as wiring something 240V in an RV, the standard RV 120V electric panel is made up horizontally, with the main 2 pole 50A breaker in the center of the panel, feeding one branch to the left and the other to the right, both 120V. In a house, the electric panel is made vertically, with the 2 pole main breaker feeding two branches that actually alternate in the panel with 120V on each branch, hence you can use a 2 pole breaker to get 240V...
Mike

This is not always true about RV's. My MH has a vertical, 50 amp panel that alternate the branches. If I had a need for a 240V circuit, I could easily add a 2 pole CB for it.

[mike1poles]

"This is not always true about RV's. My MH has a vertical, 50 amp panel that alternate the branches. If I had a need for a 240V circuit, I could easily add a 2 pole CB for it."

This is true, I was addressing the OP's question on 5th wheels, and TT's. Sorry for any confusion.

God bless,
Mike

[Route 66]

It's called 50A service because under the electrical codes, it's 240V, 50A service.

As noted when we use it as two 120V circuits, we get 50A on each leg for a total of 100A.

There are two 50A breakers for the service, which is why we can use 50A on each leg.

It's all explained here; RV Electric

[double t]

Conntek 14315 RV 1 5 Foot Pigtail Adapter Power Cord RV 50 Amp Male Plug to RV | eBay they do make an adaptor 30 female to 50 male plug

Originally Posted by mike1poles

Simple, only wire size determines amperage. True, on a 50A RV service, it has 2-50A circuits making it a total of 100 Amps. #6 wire is used and with a 4 wire, 25' power cable it is good for 60A, hence using 50A main in an RV. They make it 50A because many people add another 25' 4 wire #6 extension cable. For every so many feet, there is voltage loss and amperage increases. For the 30A, again it is wire size that determines how it is rated. There is not a 30A female to a 50A male adapter available to buy, only if someone buys separate parts and makes it themselves. But there is a 30A male to 50A female adapter available. It can be plugged into a 30A outlet in the pedestal, which splits into both circuits in the 50A RV, but you still only have 30 Amps total, because of the wire/breaker size in the pedestal.
As far as wiring something 240V in an RV, the standard RV 120V electric panel is made up horizontally, with the main 2 pole 50A breaker in the center of the panel, feeding one branch to the left and the other to the right, both 120V. In a house, the electric panel is made vertically, with the 2 pole main breaker feeding two branches that actually alternate in the panel with 120V on each branch, hence you can use a 2 pole breaker to get 240V. One of the considerations the RV industry has is in campgrounds the use only 120V service pedestals. Some do not have 240V service, some large campgrounds use what is called a wye secondary, which has 3 circuits of 120V and between the 120V legs the voltage is around 208V, not 240V. That voltage configuration, is used in businesses that have a large 120V load, but also have three phase A/C unit wired for the 208 Voltage, etc.
In our 5th wheel, I have changed out the RV type of panel to a square D, but I still only use a 50A main. Again, wire size determines that. The main reason I did it, was to add more circuits and split up what was in it, also added more outlets, for curling iron, blow dryer, etc, LOL , when momma's happy, everybody happy!!!!

Let me add one more thing, if you do not understand or know the basic principles of electricity, do not change or do anything. Have a license electrician come and talk with you and do the work. On that same note, I would not let a "dealers service center" touch a thing either. Some "techs" do have very "basic" knowledge of electricity, but that is all.

Hope this helps and God bless,
Mike

[Walt Bennett]

Hate to burst a bubble here, but my 50 amp Montana has two separate 30 amp circuits coming off the cable and into the breaker box. I know this as there are two 30 amp breakers and I took one of them and ran it to my inverter, then to the breaker so I could run that half of the breaker box off battery/inverter. The other is still straight through and its AC comes from shore power only. There aren't two 50 amp circuits.

[schrod]

Originally Posted by mike1poles

Simple, only wire size determines amperage. True, on a 50A RV service, it has 2-50A circuits making it a total of 100 Amps. #6 wire is used and with a 4 wire, 25' power cable it is good for 60A, hence using 50A main in an RV. They make it 50A because many people add another 25' 4 wire #6 extension cable. For every so many feet, there is voltage loss and amperage increases. For the 30A, again it is wire size that determines how it is rated. There is not a 30A female to a 50A male adapter available to buy, only if someone buys separate parts and makes it themselves. But there is a 30A male to 50A female adapter available. It can be plugged into a 30A outlet in the pedestal, which splits into both circuits in the 50A RV, but you still only have 30 Amps total, because of the wire/breaker size in the pedestal.
As far as wiring something 240V in an RV, the standard RV 120V electric panel is made up horizontally, with the main 2 pole 50A breaker in the center of the panel, feeding one branch to the left and the other to the right, both 120V. In a house, the electric panel is made vertically, with the 2 pole main breaker feeding two branches that actually alternate in the panel with 120V on each branch, hence you can use a 2 pole breaker to get 240V. One of the considerations the RV industry has is in campgrounds the use only 120V service pedestals. Some do not have 240V service, some large campgrounds use what is called a wye secondary, which has 3 circuits of 120V and between the 120V legs the voltage is around 208V, not 240V. That voltage configuration, is used in businesses that have a large 120V load, but also have three phase A/C unit wired for the 208 Voltage, etc.
In our 5th wheel, I have changed out the RV type of panel to a square D, but I still only use a 50A main. Again, wire size determines that. The main reason I did it, was to add more circuits and split up what was in it, also added more outlets, for curling iron, blow dryer, etc, LOL , when momma's happy, everybody happy!!!!

Let me add one more thing, if you do not understand or know the basic principles of electricity, do not change or do anything. Have a license electrician come and talk with you and do the work. On that same note, I would not let a "dealers service center" touch a thing either. Some "techs" do have very "basic" knowledge of electricity, but that is all.

Hope this helps and God bless,
Mike

I thank you very much for the lengthy reply. However, what is in bold I have purchased both products over the counter already factory made. I have a 30 female to 50 male adapter and I also have a 50 male to 30 female adapter.

[justafordguy]

Originally Posted by Walt Bennett

Hate to burst a bubble here, but my 50 amp Montana has two separate 30 amp circuits coming off the cable and into the breaker box. I know this as there are two 30 amp breakers and I took one of them and ran it to my inverter, then to the breaker so I could run that half of the breaker box off battery/inverter. The other is still straight through and its AC comes from shore power only. There aren't two 50 amp circuits.

That's odd, My Gateway has two 50 amp main breakers coming off the cable into the breaker box.

[wa8yxm]

Why is it called 50 amp? Take a look at your main breakers.. What size are they? (50 amp) So the maximum current in any one wire is 50 amps. The neutral (Which is not protected by a breaker) can not carry more than 50 amps because it only carries the difference (Which at maximum load is exactly zero) So it's properly called 50 amp.

Some salesmen will call it 100 to try and make it sound better than it is and they use your logic to justify the lie, but it's still 50 amp.

Same as your house. Likely it is either 150 or 200 amp (Check your main breaker(s) and that is what's it called. Like the RV it is mostly 120 volt (An electric Range, Dryer, Water heater Central Air conditoner or selectes shop tools may be 240 volt but many do not have those)

[mel s]

Originally Posted by schrod

I am not super electrical savvy but I can wire 120 and 240 volt circuits. I am stymied though as to why 5th wheels are said to have a 50 amp hookup. Shouldn't it be called 100 amp hookup since they are using two 50 amp 120 volt circuits? Also why are travel trailers only on 30 amp hookup if they can use an adapter to go from the 50 down to the 30? Aren't the travel trailers really still on a single 50 amp circuit (when using the adapter) since they are on a 50 amp breaker at the standup? TIA

schrod
It certainly "should be" called 100A ....but there are a lot of things about RVs that are not not as they "should be".
(BTW some people get that but most "know it alls" never will).
Mel
'96 Safari

[mel s]

Originally Posted by zman7458

Just to make sure you get this part correct. you can run a 50 amp panel from a 30 amp source because the wire in the 50 amp panel is over rated running it at 30 amps, but you CAN NOT run a 30 amp panel from a 50 amp source because the wire running to your 30 amp panel WILL NOT handle a 50 amp load without the possibility of a fire, which is the whole reason for different amp protection (breakers/fuses) in the first place. bottom line is it's all in the wire size and how much amperage it will take before catching fire.

zman7458
I disagree.
I believe you CAN run a 30 amp panel from a 50 amp source.... but only if you draw 30 amps or less.... if you try to draw more than 30 amps you risk the possibility of a fire.
Mel
'96 Safari

[zman7458]

thanks Mel s. I worded that totally wrong I was referring to the supply cord not panel, but I think it would be safer if I just remove the post. sorry for the confusion.