Dell PowerEdge 1750 Hardware Installation Manual page 12

Marking the Rack
You must allow 1 U (44 mm, or 1.75 inches) of vertical space for each system you install in
the rack. Rack cabinets that meet EIA-310 standards have an alternating pattern of three
holes per rack unit with center-to-center hole spacing (beginning at the top hole 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) for the
front and rear vertical rails (see Figure 1-3). Rack cabinets may have round or square holes.
NOTE: The vertical rails may be marked by horizontal lines and numbers in 1-U
increments. If you wish, you can make a note of the number marking on the rack's
vertical rail. It is not necessary to mark or place tape on the rack. If you choose this
method, skip ahead to the procedure "Installing the RapidRails Slide Assemblies."
F i g u r e 1 - 3 .
1 U (44 mm or 1.75 inches)
CAUTION: If you are installing more than one system, install the slide assemblies
so that the first system is installed in the lowest available position in the rack.
To mark the rack, perform the following steps:
Place a mark on the rack's front vertical rails where you want to locate the bottom of
1
the system you are installing in the rack cabinet.
The bottom of each 1-U space is at the middle of the narrowest metal area between
holes (marked with a horizontal line on some rack cabinets—see Figure 1-3).
1-6
Rack Installation Guide
O n e R a c k U n i t
12.7 mm (0.5 inch)
15.9 mm (0.625 inch)
15.9 mm (0.625 inch)
12.7 mm (0.5 inch)