20 amps to a 30 amp outlet Problem?

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
Jeff in Ferndale Wa

Jeff in Ferndale Wa

Well-known member
Joined
Mar 9, 2014
Posts
818
Location
Ferndale, Washington
Quite a few years ago, before I knew any better, I put in a 30 amp receptacle on the outside of my garage to plug in the motor home I had at the time to keep the battery charged and run the fridge if I needed to. I now have a 26' TT in that spot.

It is only on a 20 amp circuit.
I know better than to try to run too much on it, and in all the years I've had it, I'm the only one to use it, and never had any issues. Any time I've ever run an air conditioner, it's only been briefly to check to see if it's operating properly.

Is there any real problem in doing this as long as I know the limitations?
I've always thought that the worst that could happen would be that it would trip the circuit breaker.

Can I simply replace the breaker on that circuit with a 30 amp breaker to make it right, or is there more to it than that? The electrical box in the garage I believe currently has three 20 amp circuits, so I'm guessing it's 60 amp service, and I would have to reconfigure the other circuit?

I'm thinking that if it's no issue I'm not going to worry about it until the day that I may really need a 30 amp outlet.
 
You are correct that you can safely run anything that doesn't trip the breaker.  However, don't simply change the breaker to 30amps, because the wiring is only sized for 20 amps.  It's the wiring that's being protected by the breaker.
 
The load limitation of the circuit is determined by the breaker, in your case, 20A, even though you have a 30A outlet.  However, you can't just change the breaker to a 30A one unless the circuit is wired with at least 10ga wire to carry the higher load.
 
Ned said:
The load limitation of the circuit is determined by the breaker, in your case, 20A, even though you have a 30A outlet.  However, you can't just change the breaker to a 30A one unless the circuit is wired with at least 10ga wire to carry the higher load.
Click to expand...

Ned, any idea what he maximum length of that 10 gauge wire can be?  I have a sub panel in my 2 car garage and the length of the wire would probably be at least 65'.
 
There are a lot of wire size calculators on the web, and I believe we have one in our forum library.  Using that one, for 65 feet of 10ga you will have a voltage drop of 4v at 24A load, the maximum continuous load for a 30A circuit breaker.  Longer length, more voltage drop.  I would go to 8ga for that length of run.
 
Ned said:
There are a lot of wire size calculators on the web, and I believe we have one in our forum library.  Using that one, for 65 feet of 10ga you will have a voltage drop of 4v at 24A load, the maximum continuous load for a 30A circuit breaker.  Longer length, more voltage drop.  I would go to 8ga for that length of run.
Click to expand...

OK Thanks.
 
Your fine.      You would be amazed at just how much wire is in your home.  And no one concerned about about voltagevvdrop in that application. 65 feet is really not far at all.    If you said 200.  Then I might consider going to 8 gage
 
Rene,

The reply's here don't count, it is what your local electrical code requires.  Talk to an electrician and get the answer you need for your location.
 
Is there any problem doing this....

That is exactly what I did, I had no problem so long as my wife stayed out of the motor home, She had Mrs. Douglas syndrom (TV Show Green Acres where the Female Lead (Eva Gabor) kept plugging in too much stuff and blowing the generator.

And when that happens.. You got to reset the breaker is all.
 
The amp capacity of wire (ampacity is the electrical trade term)  is affected by several factors other than the wire gauge. It changes with temperature, so is affected by the number of conductors bundled together, enclosed vs open air, and ambient temps. The type of insulation is also a major factor, as is the number of connections (splices) in the path.

At 65 feet, the probable voltage drop is getting large enough to be concerned. And you will be adding even more 10 gauge wire via your shore power cord, so the total length is even greater. If you are starting out with 120v, a loss of about 4 volts isn't an significant issue, but if the source voltage is in the 115 arena, I would probably opt for 8 gauge to reduce the impact.
 
Jim Godward said:
The reply's here don't count, it is what your local electrical code requires.  Talk to an electrician and get the answer you need for your location.
Click to expand...

Jim is right, look at local codes.  I tend to overbuild everything.  So, if this were me, I would go 8ga and put in a 30 amp breaker. This might be overkill, but if you went 10ga and found the breaker  cutting out all the time, then you would have to re-wire the line and actually spend more money to do it.

As said before, the breaker protects the wire leaving the breaker box.  You want to get as much power as possible to the camper without line loss. 
 
You must log in or register to reply here.

Latest posts

Members online

Total: 1,137 (members: 28, guests: 1,109)

Forum statistics

Threads
131,988
Posts
1,388,703
Members
137,736
Latest member
Savysoaker
Back
Top Bottom