How do I determine how many volts and watts I need for a plastic ceiling lamp holder w/ outlet?

volatage in houses is 120 volts, if you bulb is 100 watts you are dealing with .83 amps. voltage times amps equals watts. So a 660 watt outlet can handle 5.5 amps. But remember you are tying into a lamp circuit which may have many lightbulbs tied to it. What it is saying, do not overload it for instance by plugging a table saw or electric heater into it

Thank you for your question regarding Pass & Seymour/Legrand 250 volts, 250 watts plastic ceiling lamp holder w/pull chain(Model #: S865WCC18). You would need a voltage meter to determine the voltage coming from your breaker panel. The wattage rating is for the light bulb(EX 60W, 100W, 100, ETC). This lampholder is rated for up to 250W's. Many homeowners are capable of installing this device but if you are unfamiliar with working with electricty, we suggest hiring an electrician.