Abstract: A power transfer switch is used between a watt-hour meter and a meter box. The meter box has main power contacts which are connected to a main power source and customer-side contacts which are connected to at least one load. The power transfer switch includes a base with first contacts for connection to the main power contacts of the meter box and second contacts for connection to the customer-side contacts of the meter box. The base has further contacts for connection with the watt-hour meter and contacts for connection with a standby power source. The power transfer switch also includes a rotary switch. The rotary switch has a first position in which the main power contacts are connected to the customer-side contacts and a second position in which the standby power source is connected to the customer-side contacts.