Running one 400w light is equal to leaving a 27 inch TV on for 24 hours. No need to worry about the bill. A hydro company is just that, a COMPANY. They just want to make money. If you pay your bill on time every month, they won't even look at you. It's when you steal the hydro, or don't pay your bill that they look into you. Just don't rip them off!
I've had CRAZY amounts of lights going before, and never had a problem.