ART 645 Use of LFMC under raised floor

[drstevens]

In art. 645.5(E) it states that an "interconnecting cable " (which in my case is from a PDU to IT rack equip.) may be ran in LFMC as long as all the conditions of 1 through 6 are met. What if one of these conditions (in my case 645.5(E)4) is not met, is LFMC with a jacket coating of PVC permitted or is plenum rated with a jacket of coating of PU required? Also, Article 645.4 states that alternate wiring methods maybe used in lieu of chapters 1-4 for power wiring, so am I correct in assuming that Art 300 doesn't apply here?

 

[__dan]

In art. 645.5(E) it states that an "interconnecting cable " (which in my case is from a PDU to IT rack equip.) may be ran in LFMC as long as all the conditions of 1 through 6 are met. What if one of these conditions (in my case 645.5(E)4) is not met, is LFMC with a jacket coating of PVC permitted or is plenum rated with a jacket of coating of PU required? Also, Article 645.4 states that alternate wiring methods maybe used in lieu of chapters 1-4 for power wiring, so am I correct in assuming that Art 300 doesn't apply here?

I'm surprised no one replied to this, I'll give it a try.

I'm on the 05 NEC so the citations are a little different.

The rule for all occupancies, other space used for environmental air, is 300.22 (C). No sealtite is listed or allowed. I am not aware of a plenum rated sealtite.

If you have a 645.4 conforming IT space (2005), secured restricted access, underfloor smoke detection, EPO, the allowances of 645.5 (D) (2) may be taken and LFMC is listed. That is wiring "to" the outlet from the PDU and "cable" is not listed.

IMO "interconnecting cable" comes with the IT equipment. It is not field supplied by the electrician. The manufacturer can use DP rated cable for interconnecting its equipment, "after" the outlet. Cable is not listed "to" the outlet. If you look for cable at 645.5 (D) (5), you would have a hard time running any type of power cable. The manufacturer may be able to under UL for interconnecting its own equipment, but not as field supplied wiring under the floor. Cable would be OK if fully above the floor and supplied by the equipment manufacturer as part of its package.

If your wiring is below the floor and the space does not conform to all of 645, 300.22 (C) applies.

Welcome to the forum