Article 645 - Corded Equipment To Underfloor Receptacle

[pharouff]

My reading of Article 645 is that there are no special material requirements for corded IT equipment as long as the cord meets the requirements in 645.5(B)(1).

The IT equipment designers are convinced that any equipment rack cords that go to receptacles in the underfloor plenum must be plenum-rated per 645.5(D)(5), and Type DP equipment cords do not exist [I believe that should tell them something].

Have any of you encountered this issue before?

 

[pharouff]

My Response to the Designers

My Response to the Designers

My interpretation of NFPA 70 Article 645 is that as long as the equipment power cord-and-plug connections are shorter than 4500 mm [15 ft] per 645.5(B), there are no special requirements for plugging into a receptacle in the underfloor plenum.

Equipment power cord-and-plug connections longer than 4500 mm would need to be replaced with an installation that meets 645.5(D)(2) and 645.5(B). That is, install a closer receptacle and shorter cord.

645.5(D)(5) material requirements do not apply to power cords. The article references in this section are for telecommunications cable types. Power cord types are listed in Article 400.

Please let me know if you disagree.

 

[cycotcskir]

there are no special requirements for plugging into a receptacle in the underfloor plenum.

Check out 400.8(2) - Uses not permitted

 

[pharouff]

We were looking at 2005 NEC 400.8(2) and 400.8(5), but we believe that our equipment rack installations satisfy 400.7(A)(6), 400.7(A)(8), and 400.7(B), so it would appear that the use is still permitted.

 

[raider1]

My reading of Article 645 is that there are no special material requirements for corded IT equipment as long as the cord meets the requirements in 645.5(B)(1).

The IT equipment designers are convinced that any equipment rack cords that go to receptacles in the underfloor plenum must be plenum-rated per 645.5(D)(5), and Type DP equipment cords do not exist [I believe that should tell them something].

Have any of you encountered this issue before?

You are correct, you don't need to have plenum rated cords if you are following Article 645. Rember that you must comply with all the requirements in Article 645 including the requirements in 645.4 for a fire-rated room and a disconnecting means.

Take a look at 645.5(D)(3) for the requirements for supply cords under raised floors. (2008 NEC)

Check out 400.8(2) - Uses not permitted

You are permitted to run flexible cord under the raised floor for information technology equipment in accordance with 645.5(B)

Chris

 

[cycotcskir]

We were looking at 2005 NEC 400.8(2) and 400.8(5), but we believe that our equipment rack installations satisfy 400.7(A)(6), 400.7(A)(8), and 400.7(B), so it would appear that the use is still permitted.

I would have to concur

 

[ron]

Be sure your jurisdiction has adopted the NEC 2008 (and of course compliant with 645.4), because the wording in 2005 and before would require DP cords.
DP cords absolutely exist and have many manufacturers listed by UL on their website.
Unfortunately, no known plugstrip manufacturer has DP cable as part of a standard part.

 

[ron]

I often try to convince my clients that cords below the floor and the few other leniencies permitted by 645, are not worth the liability associated with the requirements of 645.4 and 645.5 (mass fan shutdown with detectors below the floor).
Install per the rest of the NEC, and you don't need 645 or its headaches.