What do electricians use to test voltage?

A voltage tester is designed to test for the presence of an electrical current. It is different from a multimeter, which can perform the same basic test, but also measures the voltage, current, resistance, and more. Both devices are useful for home electrical system repairs, and they function essentially the same. However, a multimeter requires more preparation to connect the multimeter leads to the correct jacks, select between testing AC or DC current, and to move the rotary dial to the appropriate setting for the desired test.

This added complexity is more than you need if you are just testing an outlet, light switch, wires, or even a battery for an electric current. A simple voltage tester is more affordable and easier to use. Use this guide to learn how to use a voltage tester to check if power is off before starting an electrical project.

Safety Considerations

Whenever you are dealing with the home electrical system it's important to proceed with caution to help avoid accidental electrocution. A voltage tester is one tool that can help keep you safe while you work on the electrical system, but it's necessary to note that a voltage tester can give a false reading. If the batteries are dying or the voltage tester is faulty, it may beep or vibrate while testing a dead circuit.

However, the real risk is if the voltage tester doesn't beep or vibrate while testing a live circuit. For this reason, it's recommended to test the voltage tester before every use. Additionally, it's a good idea to wear insulated gloves that can help protect you from electric shock.

Before You Begin

Receiving a false positive on a dead circuit can be annoying, but isn't as dangerous as receiving a false negative when the circuit is still live. Before using the voltage tester on a circuit, outlet, or light switch that appears dead, test the voltage tester on an outlet that you know is live to ensure that the voltage tester is functioning properly. Typically, this is a receptacle that is already verifiably powering a lamp, microwave, radio, TV, or computer.

Turn the connected device on to ensure that the outlet is live and powering the device. After this quick check, turn the device off and use the voltage tester to check the outlet for an electrical current. The tester should flash, beep, or both flash and beep to indicate that the outlet is live. If the tester does not respond, then the batteries may need to be changed or the voltage tester may be faulty.

There are three main types of voltage testers. The most common option is a contact voltage tester, which uses two metal probes to test the flow of electricity. There are also non-contact voltage testers which can detect an electrical current from about an inch away, instead of coming into direct contact with the outlet or exposed wiring. A third type of voltage tester, called a receptacle tester, is made for testing outlets. This device plugs directly into a three prong outlet to provide information about the electrical current.

This is a pretty obvious piece of equipment for an electrician to have, but you’d be surprised at how many electricians and apprentices out there don’t know how to use one.  Well, let’s dive in!

For starters this is not “technically” a multi-meter.  Fluke calls it a tester, but most of us in the field still call it a multi-meter, so for the sake of this article I’m going to continue calling it a multi-meter. It has multiple functions, which is why we call it a “multi-meter.”  It can read voltage (difference of potential), amperage (current flowing in a conductor), resistance (opposition to current flow in a conductor), and continuity (whether or not you have a complete loop.

Most of the time, this is all an electrician will need to know.  This Fluke T5-600 fits in your back pocket, has detachable leads that can be snapped into the tool, or used hands-free, and a backlit LED display.  This model is one of the most used testers on the market, and because of its rigidity and reliability will continue to be so for quite some time.