How many cables can I support directly to the hanger wire before having to use a J hook? I had an inspection and the inspector said I have to use J hooks even though I only have a one or two wires ties to the hanger wire.
It sounds like you were using the ceiling support wires to support your cables. Can't do that even for only one cable. You don't have to use J hooks but you do have to provide your own means of support from the structure. You can install your own support wires like the ceiling hanger wires or something else. Just so long as your cables aren't supported by other stuff up in the ceiling or the ceiling grid.
What some electricians do is lay their wires on the floor and spray paint blue or similar. Caddy makes a special clip that goes on the grid but floats so it ties the bottom of the wire but doesn't tweak the ceiling. Its a EC311 (where did they get that number?)