Preface: I am building a charging kit that contains a long, low gauge extension cord that can be used with various NEMA plugs. For example, I can connect it to a 14-50 to make a 14-50 extension cord, or a 6-20 to make it a 6-20 extension cord. I will be keeping all of these NEMA connectors with my car so that I can use it at any house with any connector I find. 1) I would like to protect myself and my charging kit by placing a GFCI at the front of the chain (closest to the outlet). Does anybody know where I can buy a 250V/40A rated inline GFCI device for less than $250? The closest I can find is a 250V/30A device for $263. Ouch! Why are these so pricy? At that price I can make my own with a small circuit breaker box and GFCI breaker. But I'd rather have something portable. DANIEL WOODHEAD Line Cord GFCI240VAC Voltage Rating, NEMA Plug Configuration30053-0M - Grainger Industrial Supply 2) I need to standardize on a male/female system so that I can quickly change adapters (without having to manually rewire them each time). I am hesitant to use a NEMA standard male/female system because when someone sees a plug like that, it implies a certain voltage/amperage capacity, which could be misleading depending on what connector is on the other end. I will label accordingly but I would rather not create the potential for someone to plug in and get something different than is expected/standardized. Is there any 250V/50A-rated male/female connector system (3-wire, or 2-wire + ground) that I can use to connect these things so there is no ambiguity about the NEMA implications?