Standard for Safety for Transfer Switch Equipment, Meter-Mounted

These requirements cover automatic and non-automatic (manual) transfer switch equipment, operating at 600 V ac or less, intended for installation in a meter socket and used in non-hazardous locations in accordance with the National Electrical Code (NEC), NFPA 70, and the Canadian Electrical Code, Part I, CSA C22.1.

These devices are intended for use in other than life safety systems.

In the United States, these are intended for use in optional standby systems only and are not intended for use in Emergency or Legally Required Standby Systems (Life Safety Systems).

In Canada, these devices are for use in applications where loss of power is not considered safety critical.

These devices are intended for one of the following applications:

a) Permanent connection of a stationary generator to power a premise wiring system, where the generator is connected as a non-separately derived system, where the neutral (grounded circuit conductor) of the generator is not bonded to ground or the generator frame; or

b) Cord connection of a portable generator to power a premises wiring system, where the neutral (grounded circuit conductor) of the generator is not bonded to ground or the generator frame, and bonding of the neutral (grounded circuit conductor) to ground will occur:

1) In the United States, within the meter socket, or

2) In Canada, at the meter base or service box.

Note 1: In Canada, metering equipment may be connected on the supply side of the service box in some instances as outlined in the Canadian Electrical Code, Part I, Rule 6-402 (2). In the United States, installation of meter mounted transfer switches on the line side of the service disconnect is permitted by Section 230.82 of the National Electrical Code, NFPA 70.

Note 2: In Canada, emergency systems are identified as emergency power supplies. In the United States, this does not apply.

When these devices are connected between the meter mounting socket and the electric utility meter, and installed on the line side of the service disconnect, approval by the serving utility may be required before installation.

These requirements only cover transfer switches which are completely enclosed when installed in a meter socket in conjunction with the electrical utility meter.

 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.