How to Use a Voltage Tester

A voltage tester is used to check and confirm if you have electrical power.  Voltage testers help to identify electrical circuits, live wires, test switches and diagnose electrical problems.

There are many types of voltage testers but the safest to use is a non-contact voltage tester which resembles a highlighter (pen).

Things you will need

  • Non-contact voltage tester with batteries
  • Safety goggles
  • Work gloves


  1. Check to see if the voltage tester works by placing its tip inside one of the slots of a working receptacle, or, holding it close to a light bulb that is turned on.  If you see a continuous number of flashes and hear a continuous chirp it means that voltage is present and the tester is working.
  2. To test the desired outlet, ensure the power for the outlet is turned off from the main panel.
  3. Test the outlet’s receptacle – insert the tip of the tester inside the receptacle slots.  Ensure all slots are checked as the top set may have been wired differently from the bottom set.
  4. Test for hot wires inside the outlet – unscrew the receptacle and pull it out.  Insert the tester deep inside the box to test for hot wires that may not be directly connected to the receptacle.  If found switch them off from the main panel.
  5. To test a light switch, again ensure the power is turned off from the main panel.
  6. Remove the cover plate and place the tester close to the screw terminals of the switch.
  7. Once you have tested for live wires remove the screws and pull out the switch.  Test the other wires in the box.
  8. To test a light fixture turn off the power from the main panel then turn the switch to on.
  9. Remove the bulb from the fixture and insert the tester into the bottom of the socket.  Once you have confirmed that the power is off unscrew the fixture and test the wires.


  • If a wall switch controls the receptacle, make sure the switch is in the “on” position


  • Do not remove a receptacle, light switch or light fixture if the power is turned on or if you have confirmed voltage.