I don't have my 2002 book handy but 1999NEC 300-22 says no unless the wiring is needed for equipment inside the duct. The exception to 300-22 says "This section shall not apply to the joist or stud spaces of dwelling units where the wiring passes through such spaces perpendicular to the long dimension of such spaces" The way this was explained to me by my AHJ was that you cannot run wires in metal ducts but in homes with the above mentioned spaces used as ducts, wiring can be ran perpendicular to the length of the space.
Loc: North Attleboro, MA USA
I think its a hold over from when we called the space above a suspended ceiling a "Plenum" when it was used for return air for HVAC, now that space is called "Other Space for Environmental Air" 2002 NEC 300.22 (C)
The FPN makes this clear
[This message has been edited by iwire (edited 02-26-2003).]
Bob Badger Construction & Maintenance Electrician Massachusetts
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