During my first year with SDM, I uncomfortably admit that in the mid-1980s, I was sent out with an installer to observe a burglar alarm installation in a small business. Although I didn’t know it then, I later learned that the installer’s practice of laying the wire on the top of the drop-tile ceiling, in the plenum air space between the true ceiling and the drop ceiling, was dangerous and prohibited by the National Electrical Code, NFPA 70.