Electrical Penetrations

DOE-HDBK-6004-99

All safety-class circuits inside the facility should be run in trays or in rigid steel conduit for all sizes.

Safety-class circuits should be routed only through safety-class raceways. All non-safety-class

circuits originating in safety-class equipment (associated circuits) including space heater circuits

should be routed in the same manner as safety-class circuits up to the isolation device. No other

circuits should be routed through safety-class raceways.

Trough-type cable trays should be utilized where practicable. Tray strength should be verified by

tests in accordance with the latest revisions of NEMA VE 1-1991 Metal Cable Tray Systems. The

fill of power trays should be limited to 30% of usable area of 3 inch deep tray. The fill of control

trays and instrumentation trays should be limited to 30% area. The loading of each section of tray

should be calculated based upon the cable manufacturer's data.

Separate power trays and control trays should be provided in the vicinity of motor control centers

and 480 V switchgear. In outlying areas, control cable and 600 V power cables may be run in the

same tray. Lighting branch circuits should not be run in trays in any location, except for lighting

panel feeders which will be 90o C cable.

Trays for cables of different voltage levels should be stacked in descending order with the higher

voltage. Instrumentation trays should always be at the bottom. At least 12 inches of clear space

should be provided between tray levels.

Trays should be made of hot-dipped galvanized steel. Adequate tray support must be provided to

bear the electromagnetic loading in cables and trays when trays are used in areas of strong magnetic

field gradients and time varying fields.

Instrumentation cables should not share the same raceway with power cables, control cables, or

telephone cables.

Cable tray systems related to safety-class electrical systems should be designed the requirements of

IEEE-344.

Separate conduit should be supplied for the DC battery feeders.

Cable trays should be designed for a dead cable load of fifty pounds per foot, plus a single live load

of 200 pounds applied at any point along the tray between supports. In addition, tray supports should

be designed for loads due to the interaction between DC currents and the local magnetic field. In

general, the medium voltage cable trays will be sized to allow spacing between cables of more than

one cable diameter in a single layer. Fire stops of fire retardant materials will be used at floor and

wall penetrations and long vertical runs. Normally, trays will not be routed over areas of high fire

hazard; e. g., main lubricating oil reservoir, diesel generator sets, etc.

Cable tray systems related to safety-class electrical systems should be designed to the requirements

of IEEE-344.

Electrical Penetrations

Electrical penetration assemblies should be provided as a means of passing electrical circuits through

the containment building wall while maintaining the integrity of the containment pressure barrier. The