replacing a 3u power enclosure in p-class cabinet

[Koopa]

We have a cabinet with 2 x 3U power enclosures at the bottom of the rack, and then 3 x enhanced enclosures above that which are all connected using scalable bus bars. We suspect we have a fault with the lower power enclosure. I'm unsure if you are allowed to replace one of these while the whole system is up. Obviously I can switch the breakers off on the bottom enclosure, but where the cables connect in the bus bars, i'm unsure if you're allowed to remove the connection to the power enclosure i've powered off, and i'm unsure if its safe to do, as the other cabinet connections are only a inch or so away from the live connection. Please advise? Or should I be looking taking the power off to the whole cabinet to replace a power enclosure?

[Pieter 't Hart]

Seems possible

http://www.dectrader.com/docs/set1/emr_na-c00387613-2.pdf

page 42 onwards

Power Components Preparation
To service the power enclosure, bus bars, or power bus boxes, you must isolate them from the input power source.
CAUTION: The following procedures remove all power from power distribution devices and the server blades connected to these devices. To prevent possible data loss, you may choose to power down the server blades
and server blade enclosures before proceeding.