15/30/50 SHORE POWER PLUG IN ?

stevenal wrote:
These "adapters" don't seem to include circuit breakers. Your camper wiring and cord ahead of the camper's distribution panel is designed for use on a 30 A circuit protected with a 30 A breaker. The 50 A circuit will allow the wiring to overload and possibly catch fire. Are these things UL listed?

Note that going the other way is not a problem, since 15 and 20 A breakers will protect the 30 A rated circuit. Doesn't your friend have a 15 A receptacle?

Ah yes, the old "your 30 amp shore power cord could burn up if you use a 50 amp to 30 amp adapter". I did the calculations and a write up a while back on why the probability of that happening is non existent. I'm an electrical engineer. If you get a short circuit (most likely failure), then the 50 amp breaker will trip quickly. If you happen to get some fault that somehow takes in excess of 30 amps but less than 50 amps before your 30 amp breaker (extremely unlikely), then the cord will be dissipating about 100 watts. Not good, but won't necessarily burn up as much as getting warm. However, the other 5900 watts (at 50 amps) will definitely be making whatever is causing the fault to get very hot very quickly.

An analogy: If you plug an appliance with an 18 AWG cord into a 20 amp outlet in your home, the cord is not rated for 20 amps, but the cord is not going to be the thing burning up if the appliance malfunctioned. Why? Because again, short circuits are far more likely and they will trip the breaker quickly. Even if it was an very unlikely partial failure that somehow took just under 20 amps, once again, the malfunctioning appliance would be catching on fire long before the cord.