30 amp to 15/20 amp adapters

The use of a dog bone adapter is primarily for plugging in an RV not an alliance. When you plug in your 20/30 dog bone into your house, 20 amps is applied to you 30 amp cord and is run to your 30 amp main breaker in your RV. The 20 amp breaker in you house just became your RV main breaker. You will have full access to anything in your RV as long as the total amperage used does not exceed 20 amps.

You really would not have a need to go 30/20. If you were doing that then yes you would leave what ever is plugged in exposed to a 30 amp breaker.

The flip side is if you use a 50/30 adaptor. You can plug your 30 amp RV into a 50 amp plug BUT you are protected my the 30 amp main breaker in your RV. Only 1 hot leg of the 240 50 amp service is applied to your Rv.

If you are so inclined you can install a 20 amp GFI device before the appliance. I am an electrician but I would not be bothered to do that. But that is just me. Camp ground usually have a 20 amp GFI outlet available so I don't see the need to adapt down 30/20.

FYI electric language. US and Canada uses 120/240 voltage systems. Campgrounds use 50 amp 120/240 volt systems. 30 amp 120 volt systems and 20 amp 120 volt systems. 115 volt and 15 amp (language) systems went away long ago. You seem to have two threads going so you will need to read both.

As for adaptors there are many. The first # designates from and the second # designates to. 50/30. That is 50 amp 240 plug to 30 amp 120 volt plug. Only one leg of the 50 amps is applied to the 30 amp cord.

30/50 is just the reverse of that. 30 amp 120 is applied to both 50 amp legs to the RV 50 amp main breaker. Only 30 amps 120 volts is available. Go over 30 amps and the Ped breaker will trip.

Double post.

cavie wrote:
FYI electric language. US and Canada uses 120/240 voltage systems. Campgrounds use 50 amp 120/240 volt systems. 30 amp 120 volt systems and 20 amp 120 volt systems. 115 volt and 15 amp (language) systems went away long ago. You seem to have two threads going so you will need to read both.

As for adaptors there are many. The first # designates from and the second # designates to. 50/30. That is 50 amp 240 plug to 30 amp 120 volt plug. Only one leg of the 50 amps is applied to the 30 amp cord.

30/50 is just the reverse of that. 30 amp 120 is applied to both 50 amp legs to the RV 50 amp main breaker. Only 30 amps 120 volts is available. Go over 30 amps and the Ped breaker will trip.

The OP seems to be talking about a reverse adapter. 30 IN and 15 plug out. NOT the standard 15 in and adapt to the RV 30 amp cord. Now, you say you are an electrician. I find your post troubling, IF we are talking about a 15 to 30 plug adapter. I have never seen 20 to 30 or 30 to 20 adapters. They may make them, but in 40 years I have never seen one or had a customer with one. 20 amp plug ends have a horizontal pin where 15 amp ends both pins are vertical. They may have 30 to 20, but I have never seen one. The WEAKEST point when adapting down to 15 amp wall receptacle is THAT wall receptacle. It is only rated at 15 amp current and you cannot just increase the Breaker at the Main Breaker box to a 20 or 30 amp breaker to run higher than 15 amp current. The wiring from the Breaker box is also rarely rated higher than 15 amp. Now, the OP seems to be concerned if I read his post correctly, he adapts from a CG 30 amp receptacle down to 15 amp plug(NOT connected to an RV?) and he is concerned that since he HAS 30 amp supply, what happens downstream if the appliance or cords have a short that would trip a 15 amp breaker but will overload if on a 30 amp breaker and possibly cause a fire or burn up the appliance. Doug

Guess i am kinda slow this am. Really cold not figure out exactly what the OP intends to do. :h

I never use a 30 amp to 20 amp adapter except the one that one of my friends has. He used a 30 amp RV extension cord for the male end and a circuit breaker box with 2-20 amp breakers and 20 amp outlets built into it on the other end.

What do you plan to use this adapter for? Every 30amp plug I have used has a dedicated 20 amp breaker and plug next to it.

dougrainer wrote:

cavie wrote:
FYI electric language. US and Canada uses 120/240 voltage systems. Campgrounds use 50 amp 120/240 volt systems. 30 amp 120 volt systems and 20 amp 120 volt systems. 115 volt and 15 amp (language) systems went away long ago. You seem to have two threads going so you will need to read both.

As for adaptors there are many. The first # designates from and the second # designates to. 50/30. That is 50 amp 240 plug to 30 amp 120 volt plug. Only one leg of the 50 amps is applied to the 30 amp cord.

30/50 is just the reverse of that. 30 amp 120 is applied to both 50 amp legs to the RV 50 amp main breaker. Only 30 amps 120 volts is available. Go over 30 amps and the Ped breaker will trip.

The OP seems to be talking about a reverse adapter. 30 IN and 15 plug out. NOT the standard 15 in and adapt to the RV 30 amp cord. Now, you say you are an electrician. I find your post troubling, IF we are talking about a 15 to 30 plug adapter. I have never seen 20 to 30 or 30 to 20 adapters. They may make them, but in 40 years I have never seen one or had a customer with one. 20 amp plug ends have a horizontal pin where 15 amp ends both pins are vertical. They may have 30 to 20, but I have never seen one. The WEAKEST point when adapting down to 15 amp wall receptacle is THAT wall receptacle. It is only rated at 15 amp current and you cannot just increase the Breaker at the Main Breaker box to a 20 or 30 amp breaker to run higher than 15 amp current. The wiring from the Breaker box is also rarely rated higher than 15 amp. Now, the OP seems to be concerned if I read his post correctly, he adapts from a CG 30 amp receptacle down to 15 amp plug(NOT connected to an RV?) and he is concerned that since he HAS 30 amp supply, what happens downstream if the appliance or cords have a short that would trip a 15 amp breaker but will overload if on a 30 amp breaker and possibly cause a fire or burn up the appliance. Doug

Being A 50 YEAR master electrician I am fully aware of the difference between 15 and 20 amp. I try to keep things simple for the newbies. If you look at the camp pedestals you will see it is on a 20 amp breaker.
if you read my first post you see I understand exactly what he is trying to do. I stated I didn't understand why he was trying to do it but if he did then yes he would over load the adapter and the appliance with the 30 amp circuit.

Your 15 amp outlet should have a 15 amp breaker UPLINE that protects it. so if you draw say 25 amps.. CLICK and nothing

NOTE: some 15 amp outlets are protected by 20 amp breakers.. NOT a problem if it's fed properly as the outlet itself can handle 20 amps UNLESS IT IS A UNI-BOX then 10 amps is the practical limit. And some 15 amp outlets ARE 20 amp (15/20) I have three of those in this RV .

Techno-babble aside, plugging a single appliance into those adapters is virtually without risk. In home applications, 20 amp breakers are intended to protect branch circuits from being overloaded by multiple items on the same branch.
There are two possible ways to have issues. One, the appliance you are using is faulty, but that would almost assuredly lead to a dead fault that would trip the 30 amp breaker. The other, more likely and dangerous scenario is using long and cheap extension cords. Putting 15 six foot Dollar store cords together to make a hundred foot run to a long running, high amperage device like a space heater could result in the cord melting and starting a fire. But if you use a good heavy duty cord and have a bit of common sense those adapters will be fine in every day use.