Dell PowerEdge 850 - Manual (Page 23)

Rack Installation Guide
21
Wide-Hole Spacing Racks
Racks with wide-hole spacing have an alternating pattern of two holes per rack unit with
center-to-center hole spacing (beginning at the top hole of a 1-U space) of 31.7 mm and 12.7 mm
(1.25 inches and 0.5 inch) for the front and back vertical columns of holes (see Figure 1-12).
Figure 1-12. Two-Post, Open-Frame Relay Rack Wide-Hole Spacing
To mark the rack, perform the following steps:
1 Place a mark on the rack's front vertical rails where you want to locate the bottom of the
system you are installing in the two-post rack.
The bottom of each 1-U space is at the middle of the narrowest metal area between holes.
NOTE:
If your rack has wide-hole spacing, go to step 3.
2 Place a mark 44 mm (1.75 inches) above the original mark you made (or count up three holes
in a rack with universal-hole spacing) (see Figure 1-11).
Each 1 U (44 mm, or 1.75 inches) of vertical space on a rack with universal-hole spacing has
three holes with center-to-center spacing between holes (beginning at the top of a 1-U space)
of 15.9 mm, 15.9 mm, and 12.7 mm (0.625 inch, 0.625 inch, and 0.5 inch) (see Figure 1-11).
NOTE:
If your rack has universal-hole spacing, you have completed the procedure for marking
the rack.
3 Place a mark 44 mm (1.75 inches) above the original mark you made (or count up to the next
hole in the rack with wide-hole spacing (see Figure 1-12).
Each 1 U (44 mm, or 1.75 inches) of vertical space on a rack with wide-hole spacing has
two holes with center-to-center spacing between holes (beginning at the top of a 1-U space)
of 31.7 mm (1.25 inches) (see Figure 1-12).
1 U (44 mm or 1.75 inches)
12.7 mm (0.5 inch)
31.7 mm (1.25 inches)