120V Branch Circuit in Plenum Cable Under a Raised floor.

[ahartin]

We have an application at Ft. Benning, GA that the customer has asked for us to install 3 conductor plenum rated cable in a raised computer floor for floor box power. I have addressed this as not being code legal due to article 645.5(E) (2) of the 2011 NEC. The contractors engineer has answered and said it could be installed in this environment due to article 400.7 A(6) of the 2011 NEC. I do not feel that the response of the engineer addressed the location of the cable and therefore disagree with his response. Could you be so kind in helping me understand this?


Thank you for your help.

 

[iwire]

'Plenum cables' are not a wiring method found in chapter 3.

Plenum cables are not a cable covered by Article 400 at all.

 

[Gregg Harris]

We have an application at Ft. Benning, GA that the customer has asked for us to install 3 conductor plenum rated cable in a raised computer floor for floor box power. I have addressed this as not being code legal due to article 645.5(E) (2) of the 2011 NEC. The contractors engineer has answered and said it could be installed in this environment due to article 400.7 A(6) of the 2011 NEC. I do not feel that the response of the engineer addressed the location of the cable and therefore disagree with his response. Could you be so kind in helping me understand this?


Thank you for your help.

Your in the right section 645.5(D) dictates the branch circuit wiring and then the supply cords need to meet 645.5(B)

 

[dereckbc]

Short story has to be in a raceway. No need to pay extra for a cable insulation that is not recognized. Just plain ole Thhn in EMT will work just fine.

645.5 (E) 2 is pretty clear.

The branch-circuit supply conductors to receptacles or
field-wired equipment are in rigid metal conduit, rigid
nonmetallic conduit, intermediate metal conduit, electrical
metallic tubing, electrical nonmetallic tubing,
metal wireway, nonmetallic wireway, surface metal
raceway with metal cover, nonmetallic surface raceway,
flexible metal conduit, liquidtight flexible metal conduit,
or liquidtight flexible nonmetallic conduit, Type
MI cable, Type MC cable, or Type AC cable and associated
metallic and nonmetallic boxes or enclosures.
These supply conductors shall be installed in accordance
with the requirements of 300.11.

FWIW it does not matter if the installation is 645 or not. Either way it will have to be in raceway.