Generally, the lamp holder has two wiring screws. At this time, it is necessary to see whether it is a screw or a bayonet bulb, and then test it with an electric pen, so that the zero line and the live line can be confirmed clearly.

When connecting the lamp holder, one of the contacts inside should be connected to the live wire. If it is an ordinary lamp holder, the tongue should be connected to the live wire and the screw should be connected to the zero line.