In this video, Kevin O’Connor meets master electrician Heath Eastman at the shop to discuss the different types of voltages testers and their uses. Heath has four types of testers to show Kevin, including a non-contact pen tester, a full-size multimeter, a miniature multimeter, and a plug-in tester. Heath explains how each tester works, which scenarios they’re best for, and how he uses them in his work line.
Types of Electric Voltage Testers
Contactless Voltage Tester
A contactless voltage tester is shaped like a pen or marker, and it can indicate whether a wire or outlet has voltage feeding it. They’re quick and easy to use, and they can help an electrician or homeowner locate live circuits. However, they don’t tell the user how much voltage the outlet or wire has, and they’re not always completely accurate.
Pro Tip: Scott, a This Old House electrician, explains that a contactless pen tester is “a great tool for determining if a wire is live without having to go inside the wire. You don’t have to touch the copper with this.” However, he notes that you need to be mindful of orientation: “You gotta make sure you’re in the hot side of the outlet… it won’t work on that side.”
Full-size Multimeter or Contact Tester
A full-size multimeter might be overkill for homeowners, but they can tell an electrician a lot about an outlet, switch, fixture, or circuit. These voltage testers have two contact points or probes that the user can touch to the circuits’ wires to determine the amount of voltage, amperage, and resistance on the line. If the pen tester alerts a circuit having a charge, a contact tester is the best way to find out why.
Small Contact Testers
A homeowner doesn’t necessarily need a full-size multimeter, but a small contact tester can do much of the same work. These scaled-down meters have two contact points or probes, and they explain the voltage on a system in ranges, such as 24 volts, 48 volts, 120 volts, and 240 volts. They’re more affordable than full-size meters and much more compact. They’re also one of the only options for 2-prong outlets.
Pro Tip: Heath, a This Old House electrician, explains how these small contact testers work: “You plug it in and when it lights up, it gives you several different levels to tell you what voltage is present.” If the first three indicator lights illuminate — 24 volts, 48 volts, and 120 volts — that tells you the outlet is receiving 120 volts of power, not 240.
Receptacle Testers
Receptacle testers are compact and easy to use, and they provide a lot of information. While they don’t explain how much voltage a receptacle is experiencing, they do explain if there is an open ground, an open neutral, or an open hot.
They can also indicate polarity, or whether the hot and ground are reversed, or (more commonly) if the hot and neutral are reversed. These testers will only work on 3-prong outlets, and they can test GFCI outlets, as well.
Expert Insight: Bill Grande, manager for safety products at Leviton, a manufacturer of GFCIs, notes: “The great thing about GFCIs is that they protect you whether or not your wiring is grounded.” Because lightning and other power surges can damage a GFCI’s delicate circuitry at any time, Grande recommends testing your GFCI receptacles monthly using a plug-in tester or the built-in test/reset buttons.
Pros and Cons of Voltage Testers
All types of voltage meters have their pros and cons, and it could be worth keeping a few types of testers in your tool bag. While the receptacle tester is the only tester that tests polarity, it can’t quantify voltage or test two-prong outlets. Pen testers or contactless testers don’t explain voltage either, but they’re fast and easy to use. For the best results, have a few of these testers on hand before doing electrical work.
Pro Tip: When checking for power before starting work, follow the protocol recommended by veteran power station electrician Joseph Da Mour in This Old House Magazine: “First check the tester on a circuit you know to be hot, second check the one to be worked on, and finally double-check the tester on the first circuit to be sure it is still working. Also, always know the voltage-level rating of the tester.”
