Mitch, welcome to the forum! :smile:
There is a existing service with no service disconnect and the meter is back to back to the main panel that has a main breaker. If you install a service rated transfer swith on the outside of the building 10' from the meter is it required to install a service disconnect on the existing service know.
Actually, there is a service disconnect; it's the main breaker in the panel. It qualifies because, being back-to-back with the meter, it is "nearest the point of entrance" of the service conductors. But, you're going to change that.
As long as the service conductors remain outside, the service-rated T/S is fine as the service disconnect. By the way, the feeder conductors returning to the panel can not be in the same conduit/raceway as the service conductors.
Remember that, now that the breaker panel has been rendered a sub-panel, its feeder must contain a separate EGC, the electrode conductors must be rerouted to the T/S, and the panel neutrals and EGC's must be separated.
