Best practices for power cabling racks in DC

cable-managementdatacenterelectrical-powerpower-distribution-unit

With network cables it is easy. I use velcro-ties, coloured cables, 0U vertical cable organizers from APC on side of the rack — easy and neat.

However with power cables it was always giving me headaches.

With some of the racks I am using Vertical PDUs from APC (0U) so it's kind of neat as am getting 0.3m/0.5m cables and connecting them to servers which are close to the PDU sockets. It's kind of neat, but it could be better.

With horizontal PDUs it is really bad — no matter how hard I try there is always few cables that are too long and are hanging loose below the APC.

Eg. http://www.flickr.com/photos/92011471@N00/25695150/ — this will cause the cables on the bottom to be different length and its going to get quite messy…

What are best practices for power cabling? How do you guys do this so your cables once put in once are neat and you don't have to worry about them for years? Do you also cut them to match right length? Do you use some special organizers? Or maybe you know some tricks like hiding them between the side of the server and rack?

I went through many many posts on SF however most of the are oriented around network cabling and very few are touching slightly on the power problem.

Of course I am talking about having network cables on one side and power cables on the other side.

Any suggestions, recommendations, suggestions much appreciated.

Best Answer

Horizontal PDUs are a mess -- In my experience there's nothing that can be done to make these neat: You can bundle your cables neatly down the side of your rack, but when you get to the PDU they fan out into a rat's nest.

For vertical ("Zero-U") PDUs you can acquire custom-length power cables (they're available from various suppliers, usually in the same assortment of lengths you can get ethernet cables in - 1' 3' 5' 7' 14' etc.). The cables can then be bundled and tucked into the side of the rack the same way you would with ethernet cables - I use velcro ties to hold mine to the side of the rack so they don't trap server exhaust...

Some other tips:

  • Bundle your cables either by branch (if you have A/B power) or by machine.
    (If you have A/B power you can also use different color power cords to distinguish them - e.g. Black/White)
  • Label your cables (Either on the plug or on the PDU) so you know what you're unplugging
  • Remember to leave designated power points for a crash cart (keyboard/monitor) if necessary.
    (If you do not have an in-rack keyboard/mouse it IS necessary - a KVM or IP-KVM is not always an adequate substitute)
  • Don't run your AC power cables on the same side of the rack as your ethernet cables
    (You already seem to be aware of this)
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