Rockwell Automation 1771-A2BSS_A3B1SS Install Instruc Universal I/O Chassis - Manual (Page 7)

Universal I/O Chassis 7
Publication 1771–5.60 – May 1999
Connect Equipment Grounding Conductor
■ use 2.54cm (1in.) copper braid or 8 AWG copper wire to connect
each chassis, the enclosure and a central ground bus mounted
on the back-panel
■ use a steel enclosure to guard against electromagnetic
interference (EMI)
■ make sure the enclosure door viewing window is a laminated
screen or a conductive optical substrate (to block EMI)
■ install a bonding wire for electrical contact between the door and
the enclosure; do not rely on the hinge
equipment
grounding
conductors
ground lug
bolt star washer
Grounding electrode conductor
to grounding electrode system
tapped hole
ground bus
ground bus
mounting
13271
Connecting Equipment Ground Conductor to a Ground Bus
1 00 20
enclosure wall
bolt
ground lug
nut
star washer
equipment
grounding
conductor
star washer
Connecting Equipment Ground Connector to an Enclosure W
scrape paint from panel
Do not lay one ground lug directly on top of the other; this
type of connection can become loose due to compression
of the metal lugs.
Place the first lug between a star washer and a nut with a
captive star washer.
After tightening the nut, place the second lug between the
first nut and a second nut with a captive star washer.
Important:
Connect an equipment grounding conductor directly from each
chassis to an individual bolt on the ground bus.
For chassis with Connect the equipment grounding conductor using
a ground stud the grounding stud
no ground stud a mounting bolt
If the power supply has its own groundable chassis, do not connect
the GND terminal of the power supply. However, when you connect
power to a power supply without a groundable chassis (such as an ac
input power-supply module), you must also use 14 AWG copper
wire to connect its GND terminal to the ground stud or mounting
bolt connected to the ground bus.
Connect Ground Bus to Grounding-Electrode System
The grounding-electrode system is at earth-ground potential and is
the central ground for all electrical equipment and ac power within
any facility. Use a grounding-electrode conductor to connect the
ground bus to the grounding-electrode system. Use at minimum 8
AWG copper wire for the grounding-electrode conductor to guard
against EMI. The National Electrical Code specifies safety
requirements for the grounding-electrode conductor.