I remember, when I was learning the trade, I'd proudly show the boss my work, only to hear "We don't do that!"
This pic is a good example; I can't think of any sparky who would hang pipe with plumbers' tape- but I also think it is not a code violation.
Fire sprinklers are required to be mounted in a manner that will support the pipe, water, and 300 pounds of load. Sprinkler guys are only allowed to use specifically listed hangers. We are not under those restrictions.
If I recall correctly, this was a 1 1/2 pipe, containing three 2/0 wires, feeding a 150 amp panel.
