Professional electricians use a variety of testers to check a wide range of electrical functions in residential and commercial electrical wiring, and DIY homeowners will also find some of these tools useful. Learning to identify these testers, understanding their functions, and learning how to use them will greatly expand your expertise when it comes to working on electrical wiring.
Some testers are multi-function devices that can perform most, if not all, of the common electrical testing duties, while others are single-function devices that test for a single function. Various electrical testers can be used to check voltage levels in both AC and DC circuits, to test for amperage, continuity, short circuits and open circuits, polarity, and more.
Some of these terms are unfamiliar to most homeowners, but most important for a DIYer who plans to work on home wiring is knowing how to test for the presence of live voltage. Several of the devices described below fulfill that function.
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Non-Contact Voltage Testers (Inductance Testers)
Non-contact voltage testers (also known as inductance testers) are probably the safest testers around, and they're certainly the easiest to use. A non-contact tester allows you to check for voltage in wires or devices without you having to touch any wires or parts. The device is like a mini wand with a small tip on the end that senses voltage in such things as electrical wiring, outlets, circuit breakers, lamp cords, light sockets, and switches. You can get a reading simply by sticking the tip of the tester into an outlet slot or even touching the outside of a wire or electrical cable.
Inductance testers use a battery to power the device, and most models inform you of the voltage present with a red light at the tip of the tester as well as a buzzing sound. They come complete with a handy pocket clip so you can carry it close to your heart and always have it ready for safety purposes. The most basic of these tools provide simple "On-Off" information, indicating only if there is any voltage present or not. More sophisticated (and more expensive) types provide a rudimentary measurement of how much voltage is present, though the measurement is not nearly as precise as that offered by a multimeter or other voltage testers (described below).
Because this is a battery-operated device, it's important that the battery is fully charged in order for the tester to work properly. Always test the device on an outlet or switch that you know is "live" in order to verify that the tester is working correctly.
- This is a tester that most homeowners should own. Although it serves only one function—to detect and roughly measure voltage—this is the most important test for DIY homeowners.
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Neon Voltage Testers
Neon voltage testers, or neon circuit testers, are as simple as they come. They have a small body with a neon light inside and two short wire leads with a metal probe on each end. Neon voltage testers tell you only whether a voltage is present or not; they don't tell you how much voltage is in a circuit. Unlike the non-contact voltage tester, this tool requires you to touch the circuit wires, screw terminals, or outlet slots with the wire probes. This device does not use a battery, making it a very dependable tool.
To use a neon voltage tester, simply touch one tester probe to a hot wire, screw terminal, or outlet slot, and touch the other probe to a neutral or ground contact. The small neon bulb in the tip of the tool will light up if there is current present. The tester can also verify if an outlet is properly grounded: If the tester lights up when the probes are inserted into the hot slot and neutral slots on the outlet, but fails to light up when the probe is moved from the neutral to the grounding slot, it means that the outlet is not properly grounded.
This is a very easy tool to use, but it should be handled with caution: If you accidentally touch either of the metal probes during a test—and there is voltage in the circuit—you can get a shock. Carefully hold the tool's probes by the plastic casing when using a neon circuit tester.
- Because this tester is very inexpensive, most homeowners should own one, even if they also own a non-contact tester. Should your non-contact tester have a failed battery or an internal problem, the neon tester is a reliable way to check for current. It also offers a good way to check to make sure a non-contact tester is working correctly.
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Plug-In Circuit Analyzers
Plug-in circuit analyzers are inexpensive, easy-to-use testers that can tell you a great deal about the functions of an electrical circuit when you plug it into an electrical outlet. These testers are designed to test ordinary electrical outlets, but only grounded outlets that have three slots. Older two-slot outlets cannot be tested with the testers because no ground wire is connected to these outlets. Two-slot outlets are best tested with a neon circuit tester.
Plug-in circuit analyzers have three neon lights that light up in different patterns to indicate specific test results. A chart sticker on the tester helps you interpret the light patterns. Different light combinations signify a correctly wired outlet, a reverse-wired outlet, an open circuit, and the presence or lack of a ground connection. Circuit analyzers have no batteries; they simply plug into the outlet to perform the test. The outlet must have power in order for the tester to work.
- Costing just a few dollars, this is a very helpful tester for homeowners who do a moderate amount of DIY electrical work.
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A continuity tester is a device that is powered by batteries and has a probe at one end and a cord with either an alligator clip or another probe at the other end. If you touch the two together, you complete a circuit and light is illuminated on the body of the tester, indicating a complete circuit. These testers are great for checking to see if something like a single-pole switch is working properly.
Unlike other testers, a continuity tester is always used when a circuit is turned off or on wiring or devices that are disconnected from the circuit. If you are using a continuity on a device attached to circuit wiring, always turn off the power to the circuit or device that you're be testing. Or, disconnect the device entirely from the circuit wiring. It can be very dangerous to use a continuity tester on wiring that is carrying voltage.
Some electricians only use these tools to test devices that are entirely disconnected from circuit wiring. For example, the continuity tester offers a good way to see if lamp wiring is intact or if the inner mechanism on a disconnected switch is functioning properly. If a circuit has been turned off, a continuity tester also provides a method for checking wire runs to make sure that a circuit is complete. You can also use them to identify short circuits in wiring.
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- Although most homeowners will rarely use this tester, it is quite inexpensive and will find be useful for any DIYer who does a moderate amount of electrical work around the house.
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Multimeters are the most versatile of the electrical testers and, as the name implies, they are capable of many different testing functions. All professional electricians own one of these tools. Most multimeters can provide precise readings of resistance, AC and DC voltage, continuity, capacitance, and frequency. If you learn how to use all its functions, a multimeter can provide virtually all the information offered by all other testers.
Multimeters have a boxy body with a digital or analog readout, a dial for setting the test function (as well as voltage and various readout settings), and two long leads with metal probes at their ends. These testers range widely in quality and accuracy, so if you buy one, it makes sense to invest in a quality (more expensive) tool.
- Intermediate to advanced DIYers will probably want to own a multimeter, although it takes some practice to learn its various functions and how to use them. More casual DIYers will find that common testing functions can be accomplished by other, less expensive tools.
06 of 08
Solenoid Voltage Tester
Solenoid voltage testers, also known in the trade by the nickname "wiggies," are also multi-function testers, but they are somewhat simpler and easier to use than the battery-operated multimeters. Both analog and digital models are available. Solenoid volt meters are capable of testing for both voltage and polarity. Electricians use them frequently because they can test both AC voltage and DC voltage in a range from 100 to 600 volts. Pros often prefer this tool over the multimeter for many applications, since it is very rugged and has no batteries to monitor. It is not, however, quite as accurate as a multimeter for providing a numerical measurement of how much voltage is present.
Solenoid testers have two wires, each with a probe, extending out of the bottom of the tester. Solenoid testers do not use batteries to power them, so they are always ready to check voltage. The announce the presence of voltage by clicking or vibrating—the louder the clicking or more pronounced the vibration, the higher the voltage level. They have a low impedance and often will trip ground-fault circuit-interrupter (GFCI) devices or circuit breakers during testing.
- Although many homeowners are unfamiliar with the "wiggie," it is a fairly inexpensive tool (about half the cost of a multi-meter) that many DIYers find to be quite useful. A specialty electrical supply company or online retailer may be the best place to buy a wiggie, as they may not be available at big-box retailers
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Digital Clamp Meter
A digital clamp meter is a tool normally used only by professional electricians. It combines the function of a multimeter with a current sensor, and is slightly more expensive than a multimeter. There are subtle differences in function between a multimeter and a clamp meter, but the most obvious one is that this tool features clamping jaws that can grip wire conductors. This makes the tool somewhat safer and easier to use in some applications, such as when working inside an open circuit breaker panel to test individual circuits. The tool also features wire leads that allow the tool to be used in the same manner as a standard multimeter.
- The digital clamp meter is a specialty tool that few homeowners will need to own. In practice it offers functions similar to the multimeter, but its manner of use is most practical for professional electricians.
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Wand Voltage Meter
A wand voltage meter is another specialty tester usually owned only by professional electricians. This is a numerical voltage tester that can work in two ways. The tool includes wire leads similar to those found in a neon voltage tester or multimeter, which can be used to measure voltage or continuity by touching the leads to bare wires or metal contacts. But the tool also has electrostatic wands that can detect and measure voltage simply by holding them in proximity to wires or metal contacts. For example, placing the wand ears around an NM cable will give a digital readout of the amount of voltage being carried.
- The wand meter is a somewhat expensive tool that is often found in the toolboxes of pros, but one which only the most advanced DIYers will want to own.