Power Transfer Switch Burning Up

dougrainer wrote:
A Transfer switch is just 2 to 3 relay's, nothing fancy. The OP overloaded the system and the WEAKEST point failed. Which was the loose Neutral wire. The system generates extreme heat when overloaded and the Neutral burnt due to that heat. Your post is an excellent question that most people do NOT understand----Some assume that the FEED breaker will trip and save the burning or possible fire from overloading a circuit. NO always so and not so most of the time. One of the most common causes of failure of any RV transfer switch is running more amps than the feed circuit can supply. The Heat build up causes the relay's to fail. Doug

My point was the transfer switch wire burnt because it was loose and only because of that. It could burn with half the current the OP was using. A properly wired and operating 50A capacity circuit should never overheat when supplied via a 15A curcuit.

I’m a EE and understand current, voltage, etc. Heat comes from power dissipation. The equation is i*i*R. Power is poportional to resistance and the square of the current. The thing is, a 50A transfer switch relay should have very little resistance, in fact enough that 50A squared multiplied by it won’t produce more watts than can dissipate.

So in short, the loose connection caused the burnt wire issue and nothing more. We disagree only about it being “overloaded.” The more current you run through a failing connection, the more heat you produce. Yes, a fire can start without tripping a breaker as we all know you can make plenty of heat with less than 15A. I also concur that running heavy loads in a RV through multiple adapters is the best (worst) way to find those poor connections, usually starting the the receptacle in the RV.