INSTRUMENT TRANSFORMERS FOR PROTECTION AND CONTROL

The Company's protection and control scheme for a service installation may require the installation of instrument transformers in the Customer's service-entrance conductors. When the instrument transformers can be installed on the line side of the Customer's service equipment, they shall be furnished by the Company for installation by the Customer. When the protection and control scheme requires the instrument transformers on the load side of the Customer's service equipment, they will be specified by the Company but supplied by the Customer as an integral part of the service equipment. The instrument transformer installations should provide for easy removal and replacement of the transformers. The Company will purchase these instrument transformers from the Customer at the switchgear manufacturer's material invoice price.

The Customer shall provide certified test reports and curves for each instrument transformer supplied. Excitation, phase angle and ratio correction factor data are required for current transformers. Phase angle and ratio correction factor data are required for voltage transformers.

Instrument transformer replacements will be handled jointly. The Company will purchase them for the Customer to install. Instrument transformers used for metering are covered in Section 8 and are in addition to those covered here.

CUSTOMER'S SERVICE-ENTRANCE CONDUCTORS

The Customer's service-entrance conductors between the service point and the Customer's service equipment shall be subject to inspection and approval by the Company. All service-entrance conductors shall be adequately supported to withstand the mechanical stresses of the available short-circuit current. If the service-entrance conductors enter a building, other than a building or portion thereof accessible only to qualified persons familiar with the construction and operation of the apparatus and the hazards involved, the conductors shall be in a cable tray, conduit or enclosure which shall contain no conductors other than the service-entrance conductors of that particular service.

CUSTOMER'S SERVICE EQUIPMENT

Where transformed or untransformed service is furnished, the Customer shall provide and install service equipment capable of performing the following three functions:

(a) Isolate the load from the supply.

(b) Automatically interrupt load side faults and overcurrents.

(c) Simultaneously disconnect full-load current on all ungrounded service conductors when manually operated.

Equipment which performs these functions for specific service voltages is listed in Sections 6.11.1 and 6.11.2.

When service is provided and the customer service equipment is a circuit breaker, the customer shall provide a shunt trip coil in each service entrance breaker for the Company’s exclusive use. (Trip coil voltage will be specified by the Company)

For maximum safety and ease of obtaining clearance, the Company recommends that there be a single switching device (breaker, or switch and fuse), providing a single point of disconnection and protection for each service. However, up to six such devices will be accepted if (1) they are of substantially equal capacity, (2) they are located adjacent to each other, and (3) all perform the three functions described in this section.

Access to the service-entrance conductors must be provided by the Customer so the Company can test for voltage and apply safety grounds as required for maintenance work. Such access shall be located on the load side of the instrument transformers and on the line side of the Customer's service equipment.

All main service disconnects and overcurrent devices shall be clearly identified with a permanent type of marking.

Ground-fault protection of equipment shall be provided for all grounded-wye electrical services with service equipment rated 1,000 amperes or more at 277/480 volts and rated 2,000 amperes or more at 120/208 volts. This requirement for 120/208 volt service equipment, rated 2,000 amperes or more, may be waived only after the Company is satisfied that the service equipment will select with the Company's protective equipment.

The ground-fault protection may consist of over-current devices or combination of over-current devices and current transformers or other equivalent protective equipment which shall operate to cause the service disconnecting means to open all ungrounded conductors of the faulted circuit.