Some HVAC contractors around here are worse than others. But usually we can share priority. For larger pipe runs 2" and above, and for recessed cans they will work around us, especially if they had the lighting print when they engineered the mechanical. but for the small conduit runs for branch circuits and what have you we let them have priority because it is a lot eaiser to re route a 1/2" emt than a 12" solid duct. The bigger problem is usaully the superintendant because he usually says "Its not my problem you guys figure it out." And he goes back into the trailer to play solataire.
