50A only?

[42570]

What happens if an RV site offers only 50 AMP power? Thanks much.

[wkerfoot]

You purchase an adapter from the 50A to your 30A cord. The 50A service is two 30A services, rounded down.

Bill

Originally Posted by 42570

What happens if an RV site offers only 50 AMP power? Thanks much.

[Jammer]

They are rare but do exist. Forum members have encountered them.

In most cases you would see this in some situation other than a public campground. For example, I have a 50A outlet at my house but no 30A outlet. Also, most campgrounds with 50A only sites only have that situation at some of their sites, not all of them.l

There are adapters available.

[markdoane]

I've been places where the 30A sites were full and only the higher priced 50A sites were available.
The 50A power stations had both 30A and 50A receptacles, so didn't need an adapter. That might be the case where you are going.
I carry an adapter anyway.

[moosetags]

We always carry a 50 to 30 amp adapter cord. In over 700 nights of camping in Lucy, we have needed it on two separate occasions. Both of these newer campgrounds had only a 50 amp outlet at the campsite.

brian

[Minno]

I'm gonna bet that if a campground only has 50 amp service, they'll happily sell you a 50 to 30 amp adapter. Best to have one with you. Also good to always have a 20 to 30 amp converter.

Chris

[JBinKC]

Friends: I love 50 amps! My trailer's wired for two air conditioners so I have 50 amp service -- wonderful! I never run out of power. I highly recommend that others order this option. The downside? The power cord is one heavy dude. Best wishes, John

[DaveFL]

The other downside is the 50 amp service is protected at the pole by 50 amp breaker, your protection is after its connection to your input box at your 30 amp breaker. Would make it easier to burn out your wire and plugs before tripping breaker.

[wkerfoot]

Are you sure, since the 50A service is two separate 110V lines, the combined amperage is 50A but is each leg 50A?

Bill

Originally Posted by DaveFL

The other downside is the 50 amp service is protected at the pole by 50 amp breaker, your protection is after its connection to your input box at your 30 amp breaker. Would make it easier to burn out your wire and plugs before tripping breaker.

[wmarsha]

yeah, each leg has 50amp capability. So, if adapting to 30amp supply cord, there is a SLIGHT possibility of heating up your cord. It would take a RESISTIVE fault of more than 30amps-very unlikely, but possible. A bolted fault (dead short) will draw an almost instantaneous 50amps and trip the supply breaker. No one has mentioned whether the 50amp receptacles you run into are 3 wire (3 prong) or 4 wire (4 prong) I know the 4 wire is newer code, but surely there are parks that were wired with 50amp services that were 3 wire. Well, now that I wrote that, perhaps the days of the 50amp rv requirements are new enough that they are all 4 wire. I'd like to hear from those who have adapters if they have 3w adapters, or 4w, or both. thanks. bill

[Jammer]

Kirchoff's current law provides that the current is the same at all points in a circuit with no junctions. The current at the main breaker in the trailer is the same as the current at the pedestal. Therefore, there is no heightened risk of damaging the cordset by plugging into a 50 amp outlet using an adapter, unless the trailer isn't equipped with a working main breaker.

[wmarsha]

no argument there, jammer, but if your cord has a fray in it and maintains a resistive fault with say, your trailer framework (which would become a junction) while you are using max amperage inside the trailer, you could draw over 30 amps through the cord to the point of the fray-not through your trailer's main breaker. This would cause the current carrying conductor that is bare through the fray to heat-how much would depend on the actual fault. Many here have experienced the male end of their cord (the prongs) to discolor and actually heat up during normal usage-IMHO, the very end of the cable takes the brunt of wear, with the maximum amount of flexing right at the molded rubber jacket, usually causing the wires to break a few strands inside the insulation-this coupled with oxidation of the prongs of the male plug, create a resistive fault for whatever current flows through the cord-causing over years of use a mild heating condition, until finally one of the wires break fully, or the prong(s) heat so much as to cause significant oxidizing of the metal, hence a greater resistive fault. The male end of the cord is usually replaced at that point, shortening the cable 6 inches to a foot and getting the connection back into fully functional wire. The term "resistive fault" may be unknown to many, but if you think about it, a light bulb's filament becomes a "short." The filament connects one side of the supply voltage to the other. This is a resistive fault. The filament heats-what we call lighting up. The shore line can become a crude filament if frayed, etc-the difference being the metallugy of the wire (tungsten versus copper) and the surrounding environment (a vacuum versus open air).

[Jammer]

You're conflating series resistance and parallel resistance.

The heating of older plugs caused by oxidation and loss of clamping pressure is series resistance. It does not cause additional current to flow but rather causes voltage drop. The resistive heating is equal to the voltage drop caused times the current being drawn by the trailer. The effect culminates in a failure when the connector is damaged by fire or melting, or less often, when heating results in shape changes to the contacts severe enough that continuity is lost.

Such series resistance results in the current being the same at the pedestal and at the trailer's main breaker (though voltages will differ). Since breakers measure current, not voltage, the tripping behavior will be the same for a trailer breaker as it is for a pedestal breaker.

Parallel resistance between hot and neutral is usually either high (normal) or near zero (short circuit). It is nearly impossible to create a lasting (more than a fraction of a second) parallel resistance condition that would trip a 30a breaker but not a 50a breaker, either by accident or on purpose, because the power dissipated (over 3000 watts) will melt the fault thereby clearing it more quickly than the thermal trip of the breaker would. Therefore, while it is true that the pedestal breaker is what will trip, it is not true that the current rating of the breaker is a factor, since most shorts either self clear from the heat, or cause a magnetic trip. The magnetic trip points of 30a and 50a breakers are about the same with there being more differences between makes and models than there is between handle current ratings.

[markdoane]

Originally Posted by JBinKC

The downside? The power cord is one heavy dude. Best wishes, John

Roger that! I think it weighs almost 40 lbs.

Sure is nice though, to be frying bacon, making toast & coffee, running the waffle iron & space heater, microwaving veggies and running the water heater and airconditioner all at once