Art 210 requires stationary equipment that takes up 50% of a circuit's capacity to be a dedicated circuit. Other than engineering or usage convenience considerations, is there a safety issue? I recently had to repair a damaged installation that apparently was modified by a maintenance person AFTER initial construction, so that it violated the 50% rule. They tapped into a large role up door opener (in a commercial building) to provide power for a couple of convenience outlets. I don't like driving customers away by re-engineering existing installations because of code issues which aren't obvious safety issues. Anyone have some perspective about what is so dangerous about violating the 50% rule?