Figure 9-3 - hdbk109220040147

DOE-HDBK-1092-2004

RACK CABINET

Required

grounding/bonding

BAY #2

BAY #1

BAY #3

conductor to 2 and

3 bay.

Bonding conductor

Identified

equipment ground

If ac power is routed from

points.

chassis to chassis, all

parts must be NRTL listed

or labeled for the type of

Rails used for

service.

bonding.

All chassis with ac power input

shall be bonded/grounded

internally from the ground wire

Individual branch circuits

in cord.

Required

Power

bonding/grounding

Distribution

Unit

(same gauge or larger

than ac power cable)

Power Distribution Unit

NOTES: 1.

This drawing represents typical 208/120-V, Three Phase Wye, 5 wire,

ac power for Rack #1.

Multiple bays must be bonded together even if multiple Power

Distribution Units are installed in separate bays.

Figure 9-3

All grounding or bonding points should be tight for good continuity, identified by green color,

permanently labeled, and properly prepared by cleaning metal surfaces to bare metal or by the

use of serrated bushings. Anodized aluminum must be cleaned to bare metal.

The resistance across the bonding point should be very low, so that heating stress effects due

to power loss across the bonding point are minimized. If a measurement is required, the

method of measurement is to be determined by the user. The user may determine a maximum

resistance, e.g., 0.1 ohm.

9.3.4

SPECIAL CONSIDERATIONS

Systems feeding power isolation transformers must continue the equipment grounding

conductor to the equipment or the ungrounded equipment must be guarded and labeled.

For two-wire cord connected equipment, an equipment grounding connector should be installed

according to the manufacturer's instructions.

9-5