Follow standard color codes that identify each wires function in a circuit. Black means hot white signifies neutral and green indicates ground.
How To Wire A Light Switch 3 Way Switch Wiring Guide
Old light switch has 2 black wires. Its essential that you determine which black wire is hot before proceeding. And sometimes a grounding wire which is green or bare copperthere may be other wires in the box but you are only dealing with the ones connected directly to the switch. A return wire which carries the load to the fixture and may be black red or any other color except green. The easiest and safest way is to use a multimeter to test for current. However if you need to rewire a light switch or a plug socket you may occasionally come across two black wires. An incoming hot wire which is black.
In the course of replacing this light receptacle i came across two white wires. Two or three wires will be attached to the switch. Knowing which wire does what and goes where is imperative not only in the correct configuration of an electrical system but also for your familys safety. How do you find out which wire is hot or the black wire. All home electrical wires made in the us. There may also be a green grounding screw attached to bare copper circuit grounding wires but this is not always the case.
In some configurations known as a switch loop the switch may be connected to a black and a white wire that has been marked with black tape to indicate that it serves as a hot wire.