Rockwell Automation 1770 Industrial Automation Wiring and Grounding Guidelines - Manual (Page 5)

Industrial Automation Wiring and Grounding Guidelines 5
Publication 1770-4.1 – February 1998
Mounting and Bonding the Chassis
You can mount the chassis with either bolts or welded studs.
Figure 2 shows details for:
•
stud-mounting a ground bus or chassis to the back panel of the
enclosure
•
stud-mounting a back panel to the enclosure
•
bolt-mounting a ground bus or chassis to the back panel of the
enclosure
If the mounting brackets of a chassis do not lay flat before the nuts
are tightened, use additional washers as shims so that the chassis
does not bend when you tighten the nuts.
Important: Do not bend the chassis. Bending the chassis might
damage the backplane and result in poor connections.
Figure 2
Mounting Assembly Details
If the mounting bracket is coated
with a non-conductive material
(anodized, painted, etc.), scrape
the material around the mounting
hole.
Bolt mounting of a ground bus or chassis to the back panel
Stud mounting of the back panel to the enclosure back wall Stud mounting of a ground bus or chassis to the back panel
If the mounting bracket is coated
with a non-conductive material
(anodized, painted, etc.), scrape
the material around the
mounting hole.
Bolt Tapped
Hole
Back Panel Ground Bus or
Mounting Bracket
Back Panel
Nut
17664
17665
Nut
Nut
Back Panel
Welded Stud
Scrape paint
17666
Nut
If the mounting bracket is coated with
a non-conductive material (anodized,
painted, etc.), scrape the material
around the mounting hole.
Alternative bolt mounting of chassis to the back panel
Mounting Bracket
Star
Washer
Flat
Washer
Back Panel
Scrape paint
12342-I
Bolt
Tapped Hole
Use a wire brush to remove
paint from threads to allow a
ground connection.
Scrape paint on panel and
use a star washer.
Scrape paint on panel
and use star washers.
Welded
Stud
Back Wall of
Enclosure
Mounting Bracket
or Ground Bus
Flat
Washer
Star
Washer
Star
Washer
Flat
Washer
Flat
Washer Flat
Washer
Flat
Washer