Marking The Rack; Figure 1-3. One Rack Unit - Dell PowerEdge 2800 Hardware Installation Manual

Marking the Rack

You must allow 2 U (88 mm, or 3.5 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 back vertical rails (see
Figure 1-3). Rack cabinets may have round or square holes.
NOTE:
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."

Figure 1-3. One Rack Unit

CAUTION:
system is installed in the lowest available position in the rack.
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 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 1-4).
1-10
Rack Installation Guide
The vertical rails may be marked by horizontal lines and numbers in 1-U increments. If you wish,
1 U (44 mm or 1.75 inches)
If you are installing more than one system, install the slide assemblies so that the first
12.7 mm (0.5 inch)
15.9 mm (0.625 inch)
15.9 mm (0.625 inch)
12.7 mm (0.5 inch)