Greg, you may technically be correct ... but a lot of less trained, less paranoid folks are not clear on just how 240 works, and are likely to think "off" means "dead."
I agree that, while a photocell is certainly a switch, it isn't a DISCONNECT switch.
Here, again, is where good design / trade practice differs from "code." You switch ALL the hots, fuse ALL the hots, etc ... even if 'code' doesn't strictly require it.
As for wiring the photocell ... the Intermatic wiring diagrams are extremely misleading as to wiring for 208, 240, and 277. There is at least one error in the instructions. It's best to leave 'murphy' off the job, and stick with a contactor.
