Lenovo System x PDU Technical Reference page 40

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Mounting in side pocket
Mounting the Front-end PDUs (39Y8934, 39Y8935, 39Y8936, and 39Y8937) in 1U
space of the rack requires a horizontal mounting plate.
Note: The Front-end PDU is only shipped with the large vertical wall mounting plate.
The PDU can be mounted in a 1U horizontal space of the rack if you have rack PDU
hardware to mount it in. See the
horizontal panel.
Figure 16: Front-end PDU horizontal mounting in 1U space of rack
Note: You must remove any horizontally-mounted Front End PDUs from the EIA
mounting space before you relocate your rack cabinet. Horizontal installation of
Front End PDUs is not supported during relocation or shipping of a rack cabinet.
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Accessory Kit section for additional information on a