jdaasoc-- LOL! We are getting much deeper into the subject. The contractor should be aware of all codes and safety concerns. What you mentioned is true and different LOCAL codes may even spec metal conduit esp in commercial bldgs. Generally it should only be installed in exterior walls from basement to attic as it can be extended and tapped from those points. As in every project all codes must be followed. The suggestion was only made to give those thinking of current projects something to consider and consult their contractor about. Many ran extra phone lines in the past and when deciding to move up to cable modem found many cable company installers (mostly contract employees) were unable to to make a professional installation. This caused considerable cost or unsightly cable exposed. Pulling wire for any reason in exposed framing is easy-- just drill holes and cover, but once insulation, drywall, etc is installed mess and expense becomes considerable.
I've found all kinds of things in HVAC ducts. People have run phone lines, 14/2 wire, light duty ext cords, plastic tubing and copper tubing,,,,, it's an easy, if UNSAFE, gateway people have used and one reason for the suggestion of installing passageways during construction or remodeling by a contractor.
