For day 3 of Blogmas, we are going to discuss the physics of Christmas lights. It is important to find Christmas lights wired in parallel because the set of lights will still work if one light blows. This way you will not go through the struggle of hanging all of your lights just for fail when you turn them on.Lights that do not work when one bulb breaks are wired in series. In series , electricity must flow from one bulb to the next. In a parallel, each light is on its own circuit to the power source. This is why one bulb breaking will not impact the overall circuit.