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Illustrated Changes to the NEC, 2005 Edition - Part 2

Article 725

Class 1, Class 2, and Class 3 Remote-Control, Signaling, and Power-Limited Circuits

725.61 Applications of Class 2 and Class 3 Cables

New sentence identifies the type of nonmetallic raceway containing Class 2 or Class 3 cables that is permitted in “other spaces used for environmental air.”

Class 2, Class 3, and PLTC cables must comply with the requirements of (A) through (H).
(A) Ducts, Plenums and Other Space Used for Environmental Air. Class 2 or Class 3 cables cannot be run in ducts or plenums, even if plenum rated [725.3(B)], but plenum-rated Class 2 or Class 3 cables can be installed above a suspended ceiling or below a raised floor that is used for environmental air.
Figure 725-4

Listed plenum raceways can be installed above a suspended ceiling or below a raised floor used for environmental air [300.22(C)], but only if the cables contained in these raceways are plenum-rated Type CL2P, or CL3P. Figure 725-5

Author’s Comment: Nonplenum-rated Class 2 and Class 3 cables within electrical metallic tubing, as permitted by 300.22(C), can be installed above a suspended ceiling or below a raised floor that is used for environmental air.


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