Crack Down on 50 Amp Rigs Using 30 Amp Sites
I don't know how long this has been going on but I learned today that some RV parks including the Washington/Pittsbugh KOA I had booked has a policy that if your rig has 50 amp service, you can't use ...
Forum Discussion
valhalla360 wrote:
The issue is a 30amp outlet is not designed nor intended to produce continuous 30amps of power.
Sorry but that is incorrect. This is a common misconception.
Molded case circuit breakers are designed and UL/CSA listed to run indefinitely at it's rating 24/7/365. Also, the NEC requires a demand allowance for 30 amp RVs of 3600 watts (30 amps) which means a continuous load at 30 amps.
The thermal element in these breakers allows for some overload above it's rating, and the amount of time before it trips is depend on how long the overload is present and for how long. (The magnetic element in them is there for short circuits).
Below is a standard current/time graph for molded case breakers. I've made it larger to make it more legible. Looking at the curve, a 30 amp breaker should be able to handle 37.5 amps for min. 200 seconds or 45 amps for min. 80 seconds.
There's no reason to fear "popping" a 30 amp breaker when it gets to it's rating or slightly over for short periods. Things like toasters and MWs can push current over 30 amps and not trip the breaker (depending by how much and for how long). AC units can also momentarily drive current well above 30 amps during startup and not trip the breaker.
The problem in CGs is that their wiring systems aren't designed to handle many pedestals continuously at a full 30 amps on the same feeder run.
Also of note is that the "80 % load" rule in the NEC does not apply to RVs because they plug in and aren't fixed hardwired loads like in a building.
