The black wire on my plug is burnt up...

CA Traveler wrote:

myredracer wrote:

CA Traveler wrote:
Plus the maximum recommended sustained load is 80%. ie 24A for 30A power.

Where does that come from? Except for the condition of the receptacle in a pedestal and your shore power plug, you should be able to draw 30 amps continuously.

It's an NEC recommendation.

With risk of over-complicating things and making it too long:

I've never heard that being called a code "recommendation". Either there has to be an 80% derating applied depending on load classification or not. Max. voltage drop is the only code recommendation I'm aware of. An 80% derating factor does apply to fixed hard-wired loads in buildings but RVs and RV parks are specifically covered by article 551 in the NEC and there is no mention of continuous or non-continuous loads and derating there.

Art. 551.73 requires an allowance of 3600 VA per individual 30 amp site (which is then subject to demand factoring for multiple sites on a feeder or service). There is no requirement to increase a branch circuit, feeder or main service by 25% (ie., derate to 80%) within art. 551. Consider also that RVs are plug-in loads and there is no way loads can be monitored or limited so RVs will keep on drawing current up to the point a pedestal breaker will trip. You don't hear about a 30 amp breaker (or 50 amp) in a pedestal, RV panel or RV park panel tripping very often and can usually be due to overloading.

RV-ers often max. out in the summer with AC units and other loads, esp. with 50 amp RVs using 50/30 adapters. And then there's autoformers being used in some cases which can result in a maxed out pedestal breaker. Voltage drop in RV parks/CGs is a common issue in the summer due to inadequacies of the NEC but that's whole other discussion.

Breaker operation/performance is def. affected by heat. (Breaker temp. cannot exceed 90C in a 40C ambient.) The temp. it will reach includes the type of enclosure they're in. Pedestals have a single breaker operating and lot of internal volume compared to panels in a building which can have up to 42 branch breakers plus main in a cramped space. Breakers, RV pedestals, "regular" panels and panels in RVs all have their own applicable UL standards and the breaker manufacturers have relevant info. If I had the time, I'd dig deeper into all this. But it would waay over-complicate this thread anyway. :(

Having said all that, if a pedestal appears to be in poor shape or obviously is, drawing up to 30 amps for extended periods could be asking for a meltdown. Drawing even 24 amps could potentially be too much. If an RV-er is knowledgeable to know about this stuff, it comes down to maybe checking the plug/pedestal connection temp. and a judgment call.