Run a 30 amp service on a 40 amp breaker?

[Boilermaker]

Visited a park yesterday where I am considering parking my RV for a few months. The owner pointed out that the power at the site provides a 30 amp receptacle but this receptacle is serviced by a 40 amp breaker. I will be using a surge protector at the receptacle.



Looking for second, third... educated opinions.



Is this an issue I should be concerned about?


Am I risking damage to my RV's electrical system using this service?

[chuckster57]

Does the pedestal have both a 30A plug and a 15A plug?

Are you using a surge protector or an EMS ( energy management system)?

[dutchmensport]

No, you will not have any problems at all. If you exceed the 30 amp limit on your camper, regardless of the available amps at the pedestal, your camper converter and breaker box will pop the main 30 amp breaker. You camper will never allow itself to pull more than 30 amps.

Your surge protector will be just fine, because incoming 30 amps, is well ... only 30 amps, no matter what kind of breaker is behind it. The surge protector will shut down your camper regardless of the breaker size if a surge more than 30 amps hits.

I deleted my previous statement. The service is 30 amp and the breaker is 40 amp. You will have no problems at all because, your camper main breaker will pop if you use more than 30 amps. The breaker at the pedistal will pop, only if you use more than 40 amps, which your camper will never permit.

[JRTJH]

People (me included) routinely plug their 30 amp trailer into a 50 amp plug on the power pole (using an adapter).... Plugging a 30 amp trailer into a 30 amp plug that's "protected by a 40 amp circuit breaker) is essentially the same thing. You still have a 30 amp circuit breaker inside your rig that is protecting your trailer and your shore power cord.....

Is there a "slight chance of damage" ??? Yes, if the "electron princess" burps at the same time as the "copper prince bends over" and the moon is in just the right place while the "royal dog" is barking, you might get some overheating in the shore power cord.... Otherwise, chances are so remote for any damage that you'll likely never experience that "pleasure".....

With a quality EMS and your "power panel 30 amp circuit breaker" your chances of damage are remote and practically "non-existant"....

One benefit of his campground's arrangement: If you overload your trailer's electrical system on a rainy night, it'll blow the circuit breaker INSIDE the trailer, "protecting you" from having to walk outside in the rain to stand in a puddle while turning the power pole circuit breaker back on to restore power to your trailer.......

I wouldn't give a 40 amp breaker on a power pole a second thought as long as my trailer's electrical system is functional..... Now, if you change out YOUR 30 amp breaker for a 40 amp breaker (to match the power pole) all bets are off.....

[flybouy]

I too typically use a 50 to 30 amp dogbone. The 50 amp outlet is typically in better shape. HOWEVER, this didn't end well for me on the last trip out. Plugged into the 50 amp, flipped the breaker and it sounded like a transformer being hit by lightning.

The twist lock plug has been in use about 5 years without issue. The twist lock on the camper I installed in 2011. I have checked the connection on the camper every year and never had a loose screw. Unfortunately, I did not check the screws on the cord this spring (Covid had me sideways I guess). Found a replacement twist lock locally (at a ridiculous price) and used a second cord I had. The soot wiped off the side cleanly and no other damage was done.

So, lesson learned. Always check the connections every spring, especially if using a 25' fusible link.

[wiredgeorge]

Does the pedestal have both a 30A plug and a 15A plug?

Are you using a surge protector or an EMS ( energy management system)?


On the Progressive Industries website, the EMS units they sell are called surge protectors. Honestly don't know why they would market in this manner. You can get a $49 surge protector.... why pay hundreds of bucks for a surge protector (actual EMS)? Dumb marketing imho!

[JRTJH]

I too typically use a 50 to 30 amp dogbone. The 50 amp outlet is typically in better shape. HOWEVER, this didn't end well for me on the last trip out. Plugged into the 50 amp, flipped the breaker and it sounded like a transformer being hit by lightning.

The twist lock plug has been in use about 5 years without issue. The twist lock on the camper I installed in 2011. I have checked the connection on the camper every year and never had a loose screw. Unfortunately, I did not check the screws on the cord this spring (Covid had me sideways I guess). Found a replacement twist lock locally (at a ridiculous price) and used a second cord I had. The soot wiped off the side cleanly and no other damage was done.

So, lesson learned. Always check the connections every spring, especially if using a 25' fusible link.

WOW !!!! That day was "your day to buy a lottery ticket" !!!

That said, it would have happened regardless of the ampacity of the circuit breaker on the other end of your shore power cord....

[flybouy]

WOW !!!! That day was "your day to buy a lottery ticket" !!!

That said, it would have happened regardless of the ampacity of the circuit breaker on the other end of your shore power cord....

It would have happened on a 30 amp breaker but I doubt it would have made such a "spectacle" of itself.:lol: When I first saw that big black mark on the filon I just saw many, many dollar signs flash before my eyes. Thankfully, a dry microfiber towel removed it all without a trace.

[Boilermaker]

I appreciate all the on topic input and feedback.


(Didn't really need to see the results of the fireworks, though. LOL)

[chuckster57]

We strive to make sure every member gets the "full Experience" for the price of admission :D