UL SUBJECT 1008M

Abstract

These requirements cover automatic and non-automatic (manual) transfer switch equipment, operating at 600 V ac less, and intended for installation in a utility meter base, in ordinary locations only. <br>These devices are intended for use in optional standby systems only, and are intended for cord connection of a portable generator to power a premise wiring system, where the neutral (grounded circuit conductor) of the generator is not bonded to ground or the generator frame. Bonding of the neutral (grounded circuit conductor) to ground will occur within the meter base. These devices are not intended for use in Emergency or Legally Required Standby Systems. <br>The installation of these devices is intended to be under the exclusive control of the serving utility, and these are not considered under the purview of the National Electrical Code, NFPA 70. <br>An automatic transfer switch as covered by these requirements is a device that automatically transfers a common load from a normal supply to an alternate supply in the event of failure of the normal supply, and automatically returns the load to the normal supply when the normal supply is restored. An automatic transfer switch may be provided with a logic control circuit that inhibits automatic operation of the device from either a normal to an alternate supply, or from an alternate to a normal supply when the switch reverts to automatic operation upon loss of power to the load. <br>A non-automatic transfer switch as covered by these requirements is a device, operated manually by a physical action, or electrically by a remote control, for transferring a common load between a normal and alternate supply. <br>A transfer switch may incorporate overcurrent protection for the main power circuits. <br>These requirements only cover transfer switches which are completely enclosed when installed in a meter base in conjunction with the electrical utility meter. <br>Transfer switches are rated in amperes and are considered to be acceptable for total system transfer, which includes control of motors, electric-heating loads, and transformer loads.