I bought this house 3 yrs ago and there is a main panel that feeds the well pump shed, sun room and another breaker panel (that used to be the main panel before the previous owners added a sun room).
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The other breaker panel (that use to be the main panel) is located in the laundry room and I have a spare double pole breaker that I could use. My thought is to put a 50 amp double pole breaker in the spare spot and then install the 14-50R receptacle panel on the outside of the house by the laundry room and wire that straight to the 50 amp breaker.
When I need to use the generator I shut the main power switch off at the main breaker panel and at the breaker panel in the laundry room, fire up the generator and then open the generator main breaker.