On the other hand, five fingers.
- Pat Paulsen
On the other hand, "professional" installers violate the NEC every day, sometimes even at the behest of their employers, who often decide based on what they are being paid for each installation and what the risk of chargebacks are.
I hardly ever do residential installations anymore, but I still would not be averse to grounding to any convenient water pipe. Sometimes, on commercial rooftops, I ground to the electrical conduit going to heat pumps. We all do. Back before DirecTV and DISH came along, there was little attention paid to grounding, and I can tell you from personal experience that less than ten percent of the hundreds of antennas I have serviced on highrise buildings in the Washington, DC, Northern Virginia/Suburban Maryland area installed prior to the mid-1990s were grounded to code.
I personally would not be averse to running a coax in an air duct in my own home, but wouldn't do it for a customer.
In existing, single family homes, electrical codes are enforced by the mattress tag police. I would never run low voltage communications wiring in the same conduit as line voltage wiring, but I'll do just about anything else if conforming with the NEC is too costly. But then, when I worked for the state highway department thirty-six years ago, installing guardrail posts, they gave our crew a chainsaw, and if we hit rock digging our hole with a foot or two to go, "Bzzzzz...".