I have two long multi-light fixtures controlled by one switch in my bathroom. Is it safe/possible to replace/wire for four or five two light bulb fixtures? Is there a limit of wattage or any other consideration? There are no other lights or switches on the circuit.
The circuit you are talking about is probably rated at 15-Amps. The electric math looks like this: 15 (amps) x 120 (volts) = 1800-watts. It is always a good idea to derate your circuit at by 80%. (This gives you a margin of safety.) 1800 x 80% = 1440-watts. All things being equal you can install this kind of wattage on this circuit. It doesn't really matter how you do it.