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Electrical Testers, Meters and Analyzers

Why Measuring Voltage is Important

Over the years, you’ve built a toolbox of what you consider to be indispensable tools to do your job and to do it safely. Recent advances in technology and design may increase your personal safety, improve work performance and quality, and provide a surge in productivity. This article is part of a series created exclusively for White Cap electrical customers.

The Basic Tools
Testers, Detectors, and Measurement Tools are an electrician’s most important instruments. You may already have some of these in your gadget bag. But it’s important to be aware of the consistent advancements in these basic electrical tools. Let’s see which tool options are available and review their functionality. 

Measuring voltage is one of the quickest and easiest ways to determine if a circuit is live, in balance, or malfunctioning. It’s often the first step on every electrical task. Instrument manufacturers have developed a wide range of devices that are designed to be accurate, safe, and easy-to-use. There are three categories of electrical instruments.

Basic Testers  
Receptacle Testers plug into an outlet to tell you whether that outlet is working, grounded, and wired correctly. Some receptacle testers measure Ground Fault Circuit Interrupters (GFCI) and standard outlets while others test only one type of outlet. Other common wiring problems may also be identified.
Electrical Multimeter Tester
  • Non-Contact Voltage Testers are designed to allow an electrician to detect voltage with no direct contact with a circuit. These easy-to-use single-purpose essential tools are suitable for most residential and light commercial settings. Battery-operated, these testers emit a sound or light up when voltage is detected. These instruments detect any voltage that is present using inductance, and do not provide numerical current readings.

  • Neon Voltage Testers (Neon Circuit Testers) are contact instruments that are equipped with two metal probes. Electricians detect voltage by placing one tester probe to a live wire, screw terminal, or outlet slot, and the other probe to a neutral or ground contact. The tester has a small neon bulb in its tip. The tool will light up if there is current present. Electricians can also verify if an outlet is properly grounded by placing one probe into the hot slot and the second in the neutral slot. If the instrument light fails to flash when the probe is moved from the neutral to the grounding slot, it means that the outlet is not properly grounded.

  • Plug-in Circuit Analyzers have become extremely useful instruments for a quick check of an electrical system. Current plug-in circuit analyzers allow you to verify proper wiring and GFCI operation. These instruments can also identify and locate loose wire connections, bad splices/receptacles, and high-resistance grounds. Another useful analyzer function is the ability to test line voltage and voltage drop under full load without adding electrical stress to the circuit. No single instrument offers every diagnostic capability, so check specifications before you buy.

  • Circuit Breaker Finders allow electricians to identify and label existing circuits. They are useful when renovating older structures. Circuit breaker tracers perform the same function but have additional testing capabilities to allow greater diagnostics.

  • Continuity Testers allow electricians to determine if there is a complete path for current to flow. They are commonly used to test switches, fuses, electrical connections, and individual conductors. The test instrument emits an audible response (beeps) when there is a complete path. 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.

Measuring Electrical Loads

Circuits deliver energy to a load, or an electrical device ranging from a TV to a large industrial motor. Usually the loads have a label, possibly even a schematic, that identifies their voltage and current. These numbers confirm what readings a load should be operating at normally. 

Using these instruments, you can quickly identify if the circuit is operating at a different voltage than what is expected, and take the appropriate steps to correct the problem. 


  • Electronic Voltage Testers: Used to measure alternating current (AC) and direct current (DC). Receives a numerical voltage reading, and some electronic voltage testers also measure continuity. 

  • Solenoid Voltage Testers (aka “Wiggies”): Using input impedance and placing a small load on a circuit, you can test receptacles, certain photocells, dimmer switches, a poor connection, parallel wires, lamp sockets, electrical panels, fuses, and switches. However, it won’t give precise voltage. This multi-function tester is easier to use than a battery-operated multimeter. Wiggies can test AC and DC in ranges from 100 to 600 volts.

  • Multimeters: This meter measures volts (E), amps (I) and ohms (Ω), and it can provide precise readings of resistance, AC and DC voltage, continuity, capacitance, and frequency. Multimeters perform common electrical testing functions such as:

  • Measure voltage, resistance, continuity, and current
  • Determine if an electrical device is functioning
  • Confirm that outlets are working, grounded, and wired properly
  • Let you know which circuit breakers control which outlets

There are two main types of multimeters: analog and digital. Multimeters vary in size, features, price, and they can be portable handheld devices or highly precise bench instruments.

How to Select the Right Multimeter

Consider these key questions when purchasing a multimeter:

  • Does it measure AC and DC voltage?
  • Does it measure resistance and continuity?
  • Can it easily measure current?
  • Can I easily read the display?
  • Is it safety rated to at least CAT III 600 volts?
  • Is it small enough to carry in my pocket or bag?
  • What is its safety drop rating?
Electrical - How to Select the Right Multimeter

Digital vs Analog:

Electrical - Analog vs Digital Multimiter Table

Clamp Meter
A clamp meter measures current in a circuit by clamping the meter around a cable, wire, or another conductor for an accurate measurement without disconnecting or cutting the power to any wires. Probe-style testers require cutting or disconnecting power. Clamp meters come with basic functions or with added features such as voltage, continuity, and resistance measurement functions.
Electrical Clamp Meter
Many electricians prefer clamp meters over multimeters because they do not have to power down, set up connections, and power up to get measurements. Also, when safety is a concern, unlike multimeters, clamp meters do not require physical contact with test points.

Other Instruments

Thermometers are used to measure operating condition of electrical equipment and circuits. Infrared thermometers measure the temperature of an object or area without making direct contact but by using infrared light. These are useful when the control box is elevated and out of reach. When determining electrical conditions, Digital thermometers measure an object or area’s temperature with a precise readout when accuracy is important. 

Moisture meters measure the amount of dampness on substrates such wood or concrete. This measurement is helpful when trying to determine if electrical equipment may be exposed to high humidly or excessive moisture problems.
Productive and Safe
Whether you’re involved in a renovation or new construction, you can count on White Cap to provide a wide variety of testers and meters ranging from basic go-to non-contact voltage detectors and voltage testers with continuity detectors, to open-jaw current testers and open-fork testers.
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