Safely check if your electrical wires are functioning properly
Electrical testers and meters are diagnostic tools that let you know if the wires you are working on are hot, if an electrical device is functioning, and if a receptacle is wired properly.
This guide will introduce you to the most common electrical testers and meters and explain the tests and measurements they’re designed to perform, so can you can feel confident you’re selecting the right meter or tester for your project.
Voltage testers, circuit breaker finders, continuity testers and receptacle analyzers all detect the presence or absence of electrical voltage.
Voltage testers detect the presence or absence of electrical voltage in cable, wires, circuit breakers, light fixtures, outlets and switches.
Use these to be sure the power is off at an outlet or other device with which you will be working.
Non-contact voltage testers provide a reading on the wires or devices being tested without needing to touch the wires. They emit a sound or give off a light when voltage is detected, but do not provide a numerical reading of any voltage that’s present.
Electronic voltage testers measure alternating current (AC) and direct current (DC) and give a numerical reading of the voltage present. Some electronic voltage testers also measure continuity.
Circuit breaker finders identify the circuit breaker that controls an outlet. They consist of two parts: a transmitter and a receiver. The transmitter is plugged into the outlet in question and the receiver is passed over the circuit breakers in the breaker panel.
When the transmitter passes over the correct breaker, it emits a sound or lights up, making it easy to know which circuit breaker to turn off before you work on an outlet.
Some circuit breaker finders include a light socket adapter for finding the circuit breaker that controls a light fixture.
Continuity testers are used to determine if a light switch is malfunctioning. They measure whether an electrical circuit is open or closed.
A light switch circuit is closed when the light is on and open when the light is off.
Open circuits cannot conduct electricity while closed circuits have continuity and conduct electricity.
Be sure to turn off power to a circuit before performing a continuity test.
Receptacle analyzers plug into an outlet to tell you whether that outlet is working properly and safely. Some analyzers test both ground fault circuit interrupter (GFCI) outlets and standard outlets. Different lights will glow to show you when the outlet is working, grounded and polarized.
While there are several meter types, a multimeter is the most economical as it performs several functions in one unit.
One multimeter can take the place of a voltmeter, which measures voltage; an ammeter, which measures current; and an ohmmeter, which measures resistance.
Multimeters come with black and red lead testers, probes attached to the ends of wires, that can be held against battery terminals or inserted into outlets for testing.
More advanced models measure continuity, temperature and more.
Digital multimeters display measurements as a number and offer the most reliable readings.
Analog mulitmeters display measurements across a bar.
Auto-ranging meters are available that do not require you to manually set the expected voltage range.
Professional multimeters include features such as backlit displays, work lights, high safety ratings, magnetic mounts and more.
Clamp meters are used primarily to measure current, though many models will also function as multimeters, measuring voltage, temperature and more. While clamp meters are similar to multimeters, they offer the advantage of measuring the current in an electrical conductor, such as a wire, by letting the wire be threaded through the clamp opening, avoiding having to disconnect the wire.
Low-voltage meters are used to test for good connections, opens, shorts and cross connections in cat5, cat5e, cat6 or coax cables, which run phone lines, computer networking cables, home automation networking cables, television signal cables and audio/video distribution cables. These meters also test the connections that keep your home office or home theater equipment communicating.