Exterior Electrical Utility Service

DOE-HDBK-1132-99

Minimum bending radius of new cables should not be violated when

pulled through existing raceways.

Evaluate the conduit and tray support system to stay within design loads

when new cables are added.

When pulling cables in existing trays, refer to IEEE-1185 for guidance for

avoiding damage to cables.

2.2

Exterior Electrical Utility Service.

Demand and diversity factors should be considered in calculating service

capacity, substation, and feeder loads. Actual demand data should be used, or

the latest edition of Standard Handbook for Electrical Engineers by Fink and

Beatty should be referenced to obtain typical demand and diversity factors for

industrial loads.

Loads that require a high degree of service reliability may be accommodated by

redundant services from the utility or a single service supplied from a loop-type

transmission/distribution system having sectionalizing features. Reliability

analysis is recommended to ensure the facility production targets are met.

It is essential to maintain the appropriate power factor at the service connection

to the utility in order to save demand charges, when tariff is based on kWH and

kVA demand. Cost studies are recommended to arrive at the optimum kVAR

rating of power factor correction capacitors.

Single-pole structures are preferred in most applications. Joint use of poles for

power and communication circuits is permissible, provided safe clearances are

maintained in accordance with the National Electric Safety Code. High-load

clearance to power lines should be considered during the design, depending on

the site requirements. Power lines in the vicinity of helipad or emergency

operation centers, where helicopters may be in use, require aviation warning

markers.

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