Generac, 200 Amp Smart Switch, service entrance 1O NEMA 3R. This 200 amp automatic transfer switch is used for transferring electrical load from a utility (normal) power source to a generator (standby) power source. Transfer of electrical loads occurs automatically when the utility power source has failed or is substantially reduced and the generator source voltage and frequency have reached an acceptable level. The transfer switch prevents electrical feedback between two different power sources (such as the utility and generator sources) and, for that reason, codes require it in all standby electric system installations. The transfer switch consists of a transfer mechanism, utility service disconnect circuit breaker and a Smart A/C module incorporating fuses and two terminal blocks for transfer switch connections.