Meter Socket Grounding

Meter sockets or enclosures shall not be used for the purpose of grounding cable TV, telephone, or any other service lines.

Self contained meter sockets and transockets shall not be separately grounded unless the electrical inspection agency requires the neutral conductor to be isolated in the socket, or the socket is used on an ungrounded 230 volt service.

All instrument transformer rated sockets and enclosures shall be grounded. Refer to Figure 23.

Refer to Section 3.4 Service Grounding for more information.

MULTIMETER INSTALLATIONS

Meters for all Customers in a multiple-occupancy building shall be grouped in a minimum of locations. For all multimeter installations, the Customer, electrical contractor, or builder shall submit a detailed plan to the Energy Technology Services Department for its approval before equipment is purchased or meter installation is started.

The meter socket and main service equipment for each individual apartment, office, or storeroom shall be clearly and permanently identified by the Customer or his electrical contractor. If changes in apartment numbers are made after the meters are set, the Company shall be notified immediately by calling Customer Relations at 412-393-7100.

For installations of two to six meters, the service-entrance conductors shall enter the top or bottom of the meter socket, as shown in Figure 19. When entering the top, a hub shall be used. Hub openings not used shall be covered with a closure plate.

For multimeter installations of more than six meters, a circuit breaker or a switch with fuses shall be installed on the supply side of the meters. The unmetered conductors shall be brought out of the switch or breaker compartment in metallic conduit to a sealable wireway or wiring trough. All taps to the meter socket shall be made in the wireway or wiring trough as shown in Figure 20.

If the building owner elects to use prewired, combination multiple meter and breaker panels for multimeter installations, the complete panels shall be furnished by the owner. A list of approved manufacturers of prewired, combination multiple meter and breaker panels is available from the Energy Technology Services Department. Prior to purchasing, the details of all equipment and the installation plan shall be submitted to the Energy Technology Services Department for approval. The essential requirements for this equipment are the use of Belleville-type washers and oxide inhibitor on all aluminum to aluminum connections, provision for installation of a fifth terminal in the 9 o'clock position of each 120/240 volt, single-phase meter socket, sealable separate compartments for unmetered wiring, and no metered and unmetered wiring in the same compartment. A typical installation of prewired equipment is shown in Figure 21.

In multimeter installations where meter sockets are located on the load side of the service disconnecting means, and where the neutral is grounded to the case of the service disconnecting means, local electrical inspectors may require that the neutral bus in the meter sockets be isolated from the meter socket frame. However, such isolation of the neutral conductors in the meter socket is not usually required if the meter socket is located within view in the same room near the service disconnecting means.