Wiring methods and cabling systems listed for use in plenums shall be permitted to be installed in ducts specifically fabricated for environmental air-handling purposes if which conditions are met?

Wiring methods and cabling systems listed for use in plenums shall be permitted to be installed in ducts specifically fabricated for environmental air-handling purposes if which conditions are met?

• A. Total length does not exceed 4 ft
• B. Only if necessary to connect to equipment associated with the contained air
• C. Both of the above
• D. Neither of the above

Answer: (C)

In plenums, wiring methods listed for use in environmental air-handling spaces are tightly controlled because air-handling ducts can spread smoke and flames. The allowed installation inside ducts specifically fabricated for environmental air handling is limited to two conditions. First, the total length of such wiring inside the duct must not exceed a short run—the limit is four feet. Second, the wiring may be installed there only to connect to equipment that is associated with or located within the contained air within the duct. This means you’re not allowed to run these cables long distances through the duct or use them merely to pass between spaces; they’re limited to a short connection to contained-air equipment. Therefore, both conditions must be met for this installation to be permitted. If either condition isn’t satisfied, these wiring methods aren’t allowed in the duct.

In plenums, wiring methods listed for use in environmental air-handling spaces are tightly controlled because air-handling ducts can spread smoke and flames. The allowed installation inside ducts specifically fabricated for environmental air handling is limited to two conditions. First, the total length of such wiring inside the duct must not exceed a short run—the limit is four feet. Second, the wiring may be installed there only to connect to equipment that is associated with or located within the contained air within the duct. This means you’re not allowed to run these cables long distances through the duct or use them merely to pass between spaces; they’re limited to a short connection to contained-air equipment.

Therefore, both conditions must be met for this installation to be permitted. If either condition isn’t satisfied, these wiring methods aren’t allowed in the duct.