Branch Circuits for Data Racks

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dvw

Member
Location
Mississippi
Occupation
Engineer
I have a few data racks with some 120V/20A circuits in 4x4 boxes overhead near a cable tray. The circuits currently terminate into some duplex outlets in the 4x4 boxes.

I've seen some other installations where, instead of using duplex outlets overhead, SJ cable enters the overhead 4x4 box and then drops into the rack with another 4x4 box where the duplex outlets are located. Is this acceptable?

Thanks!
 

tallgirl

Senior Member
Location
Glendale, WI
Occupation
Controls Systems firmware engineer
They likely did that because no one ever introduced them to twist-lock devices.

That said, I've never been in a data center where it was all fixed wiring until you got to the racks.
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
A lot of computer racks can be purchased with what they sometimes call a power distribution unit, It looks to me like run of the mill power strip with a cord on it that you plug into a wall outlet.
 

dvw

Member
Location
Mississippi
Occupation
Engineer
A lot of computer racks can be purchased with what they sometimes call a power distribution unit, It looks to me like run of the mill power strip with a cord on it that you plug into a wall outlet.
These racks have vertical PDUs, but they connect down to a UPS system at the bottom of the rack. The UPS systems only come with like a 10ft cable, so it's unable to reach the outlets at the tray location.
 

JoeStillman

Senior Member
Location
West Chester, PA
From the NEC:

400.12 Uses Not Permitted. Unless specifically permitted in
400.10, flexible cables, flexible cord sets, and power supply cords
shall not be used for the following:
(1) As a substitute for the fixed wiring of a structure...
 

petersonra

Senior Member
Location
Northern illinois
Occupation
engineer
400.10 Uses Permitted.
(A) Uses. Flexible cords and flexible cables shall be used only
for the following:
(8) Appliances where the fastening means and mechanical
connections are specifically designed to permit ready
removal for maintenance and repair, and the appliance
is intended or identified for flexible cord connection.
 
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