Updated on 19 October, 2021
If you're looking for a simple way to check the electricity in your home, a non-contact voltage tester is your best option. These products are available at most home improvement stores and are usually easy to use. They are also quite inexpensive, which makes them a great buy for any budget. But what exactly are these products and how do they work?
To use a non-contact voltage tester on a wire you must first touch either the tip or the nose of the multimeter to both of the wires. Then, as you would with a regular multimeter, you need to look up the resistance of the conductive substance to determine the current. Most testers will make a beep or glow and light up to confirm current is present.
The first step in using a non-contact voltage tester is to make sure that the wire is not attached to anything. For instance, it's impossible to test a three-pronged outlet or power cord with a wire tester. However, you can use this type of tester on most wires, including vehicle electrical wiring, extension cords and telephone wiring. It's important to note that if the wire in question is much heavier than 18-gauge, it may be difficult to install the probe.
Most of these devices look like small metal or plastic cups. One side of each cup has a contact area, which is where you will place the non-contact voltage tester. Usually, there is a notch on top of each side for you to insert the probe. Press down gently on the side of each cup to push the probe into the insulation. You can either use your fingernail to push the probe into the wire, which is more convenient, or use the side of the cup with the notch for firm grip.
If the wire doesn't fit into the cup, it's OK. This tool isn't designed to test all types of wires. Instead, you should only use it to test one outlet at a time. With a multimeter, you can test three outlets at once. However, if the outlet you are testing is a three-pronged electric outlet, it will take two tries to get the two prongs to contact. This makes using a non-contact voltage tester difficult.
Capacitively Coupled Circuitry testers are used most often to detect faults in three-pronged electrical circuit breakers. There is a detector installed between the isolation solenoid and the insulation. When the circuit is tripped, either current flows through the two points or the circuit breaker trips. The detector senses this and triggers the tester. Unlike other non-contact voltage testers, those that are capacitively coupled are sensitive enough to detect even the smallest of currents.
A neon voltage tester works by exposing a charged wire to a small amount of neon gas. Once the wire contacts with the gas, either current flows through the wire, or the outlet breaks, creating an alarm. Like the capacitor-based testers, this kind of tester has a sensitive detector that triggers when current flows through the wire.
Some people might think of an unprotected electrical outlet as a safe haven for many different voltage sniffers. However, most testers designed for ungrounded outlets have very limited functionality. Many are only designed to work with one specific outlet. Others might have limited or no functionality at all, depending on their circuitry. These specific types of tester are most useful for testing purposes that require a more permanent solution. Whether you need a portable outlet simulator, a grounded outlet simulator, or both, make sure to check out some different models before making a purchase.