The power rating of Christmas lights varies depending on the type of lights and the number of bulbs. Incandescent mini lights typically have a rating of 5-10 watts per string, while LED mini lights typically have a rating of 0.5-0.75 watts per string. It's important to check the packaging or manual for the lights you're using to ensure that the wattage is appropriate for the number of lights and the circuit you're using. Overloading a circuit with too many lights can lead to a power outage, a fire hazard, or damage to the lights themselves.