Service Equipment, 480 Volts Or Less

Where service is furnished at 480 volts or less the Customer's service equipment shall consist of any of the following types:

(a) Either a low voltage power circuit breaker or a molded case circuit breaker rated in excess of the available short-circuit current. Draw-out breakers are preferred for the visible clearance feature.

(b) A bolted pressure contact type switch with silver-sand fuses of high interrupting capacity.

(c) A heavy duty fused safety switch with ampere rating of not less than 100 amperes. The switch and fuse combination shall have a rating in excess of the available short-circuit current.

Service Equipment, 2400 Volts Or Higher

Where service is furnished at 2,400 volts or higher, the Customer's service equipment shall provide visual clearance for the service conductors and consist of circuit breakers or fusible load-break switches of the following types:

(a) Either a draw out or stationary power circuit breaker. Stationary circuit breakers shall have a disconnecting switch (preferably interlocked) on the supply side to provide the visual clearance. Circuit breakers shall be equipped with current transformers and overcurrent relays for each service phase and a ground relay for three-phase services. The relays must be set to coordinate with Duquesne Light protection. Special cases may require additional protective equipment or controls to ensure proper operation and coordination. The source of tripping energy should be from a battery (minimum 48 volts DC) with an adequate charger. Other types of trip sources require the approval of the Company.

(b) A Load-break air, oil, vacuum or gas switch, plus fuses of proper size and rating installed on the load side of the load-break switch. The open position of the contacts of the switch shall be readily visible. Switches without contacts visible in the open position shall have a disconnecting switch (preferably interlocked) on the supply side to provide the visual clearance.

Exception - For special outdoor installations subject to the Company's approval, several circuits may be connected to one load-break air switch with separate fuses or circuit breakers for each circuit. Such fuses or circuit breakers shall be located in the same substation area and be readily accessible from the load break switch. The load break switch and the circuits controlled by it shall be permanently identified.