Gentlemen- & Ladies if your listening. If I'm inspecting a job that involves a job that specs out a "Transfer Switch" You can bet your bippie that I will be looking for somthing that is "Listed for the purpose" If I'm looking at a simple residential generator / DPDT switch I probably won't have a problem. Gentran makes some equipment that I find to be very well constructed and it has a UL label ta boot. I personally have a DPDT Wadsworth switch that I use with my generator and I find it very acceptable. It sure beats the scenario of the 'electrician" who known better. back feeding a dryer or range plug with a cord with two male caps on it and making sure he turns the main off in his panel.