Cool Tools: Using Electrical Testers Safely

Much attention is devoted to safe work practices during electrical construction, maintenance and repair work, and rightfully so. Occupational Safety and Health Administration (OSHA) statistics consistently place electrical-related accidents in its “Fatal Four” leading causes of workplace deaths: falls, struck by objects, electrocution, and caught in between.

Industry publications regularly report on safety, including the use of the proper tools and equipment for electrical work and wearing the required personal protective equipment (PPE) for each work-site situation. However, testers often aren’t included in safety articles, and using the wrong tester, or improperly using testing equipment, can have fatal results.

Some of the most frequently used test instruments include noncontact voltage testers, multimeters, insulation testers and ground-resistance testers. Representatives of five tester manufacturers share their thoughts on the safe use of their products.

Jeffrey R. Jowett, Megger’s senior applications engineer, said: “Safety in operating and working around electrical equipment involves both practice and the right equipment. Workers must follow safe working practices and be equipped with reliable equipment, preferably with state-of-the-art safety features.

“The first consideration is in the approach to the equipment or electrical environment. Remember, electricity can kill from a distance. High voltage can provoke an arc to metal or even to pointed objects from distances of many feet. Common work environments don’t pose this danger, but some do. Safeguards should be in place before entering the work area. The most effective measures are safe practices and protective clothing, but the worker can be made aware of high voltage in proximity by wearing or carrying a voltage detector.

“These devices, often called ‘tick tracers,’ work by cutting the flux lines around a voltage source. As the device enters a high-voltage environment, flux lines create a voltage gradient across the device, and this voltage generates visible and audible alarm signals warning of a nearby source of voltage.

“Next is the issue of actual contact with equipment. Industry standard lockout and tagout procedures ensure that equipment and circuitry is de-energized, but such practices should always have redundant safety backup.

“Then comes working on the equipment or circuit, and for this, the test equipment must be redundantly safe. If lockout and tagout fails or is interrupted, any test instrument connected to the circuit should come alive, visually and audibly alerting the operator that the circuit has become live. For redundant safety, this function should occur automatically in any test position and not have to be asked by a dedicated selector switch position. Finally, at the conclusion of the test, instruments should also indicate safe disconnection. Some electrical tests, such as DC [direct current] insulation testing, can apply a static charge to the item tested. This voltage can be lethal. Any tester performing any such function should be complete with a discharge circuit and automatic warning to let the operator know what is happening and when it is safe.

“Lastly, possibly the greatest single safety feature is the IEC 61010 rating for arc flash and arc blast protection. This rating should be understood by everyone operating electrical test equipment. It describes the degree to which the instrument is protected, by its design, from arc flash and arc blast in the event of major disturbance on the line while the test is engaged,” Jowett said.

John Olobri, AEMC’s director of sales and marketing, said: “Insulation testers, multimeters, ground-resistance testers, and noncontact voltage testers are among the most common instruments for making routine electrical tests. One of the most common risks during testing is using an incorrect instrument for the test that is not rated for the voltage at the test point. Minimally, instruments should comply with 300V, CAT III standards and as high as 1,000V, CAT IV.

“The person doing the test must understand and use the proper PPE clothing and procedures required for the work environment and operate testers as instructed in the product manual. They should read the safety instruction section of the product manual.

“Audible tones and visual warnings on the display of instruments identify voltage levels measured at the test lead connection. Testers should automatically abort tests when unsafe voltages are present. Product housings should be double-insulated, and test leads comply with and are certified to standards such as UL, CSA ETL, CE, etc.,” Olobri said.

Sam Ruback, FLIR’s product manager, test and measurement, said: “Important features on the latest testers relate directly to safety and include Bluetooth connectivity, enabling users to monitor readings remotely at safer distances from hazardous electrical components and dangerous machinery and stream data in real time to smartphone and tablet devices; built-in LED work lights; built-in IR thermometers to make quick, noncontact temperature checks on components; large, intuitive backlit display screens; and automatic data recording, which eliminates the need to stand near inspection targets for long periods while trying to detect and record intermittent anomalies.

“[The] tester should be certified and display a label of an independent verification lab, such as UL, CSA, CE, ETL or TUV. Make sure your meters and test leads have an adequate [category (CAT)] safety rating. Sometimes, the only thing standing between an electrical contractor and an unexpected spike is their meter and leads,” Ruback said.

Duane Smith, Fluke Corp.’s digital multimeter product specialist, said: “The single most important aspect of electrical measurement safety is following NFPA 70E. Work de-energized whenever possible. Know the arc flash potential of the cabinet and verify test tools are functional and rated high enough for that electrical environment and for the measurements to be made. Wear the appropriate PPE for the environment until the cabinet is confirmed de-energized.

“For routine tests, most electricians start with a noncontact voltage detector. They then proceed to their all-purpose tester, either a fork tester that measures current and voltage or a digital multimeter.

“Meters without independent certifications should not be used.

“Again, the single biggest risk is working live and not wearing proper PPE. Following that is using a test instrument that has not been properly verified as appropriately rated, fused and functional before the live testing. Another common mistake: Test leads plugged into the amp jacks of a meter, then attempting to measure voltage—causes an immediate internal short.

“Single biggest safety improvement? Wireless meters that allow the user to reduce the risk of arc flash by connecting to a wireless test tool, closing the panel cover and then observing the measurements wirelessly, out of harm’s way. Other advances include electronic versions of the classic solenoid tester—­electronic models still vibrate like a solenoid, but they are protected with fuses; meters that can be hung up with a magnet so that the electrician has the tool in clear view and his hands are focused on test points; and retractable test leads that allow the user to shroud the lead tip in high energy cabinets but expose the leads for lower energy work. Some meters have noncontact volt detectors built in so that electricians can verify de-energized state.

“Also, adopting infrared as a noncontact inspection approach not only keeps the electrician away from the cabinet (though some PPE is still required). Also, regular infrared inspections increase the likelihood that issues will be found before a failure-induced accident,” Smith said.

According to Jim Gregorec, Ideal Industries’ business unit manager—T&M: “Safety regulations continually elevate safety requirements to protect the users and circuits under test, so it’s important to keep your test tools current. Category-rated test tools and beefier test lead construction with shielded probe tips and more detailed safety warning requirements are three significant improvements in recent years.

“With the hazards of electrical shock and arc flash/blast potential, it’s very important to know the working environment and match the PPE and test tool safety ratings to the job at hand. Additionally, using good measuring practices ensures that your test tool is set up and working properly.

“Clamp meters are quite versatile troubleshooting tools for making a multitude of measurements, including amperage, voltage and resistance with some specialty functions, such as frequency and capacitance. Basic voltage testers are very good for verifying the presence of voltage or ensuring that a circuit is dead based on their simplicity. Insulation testers are used to verify cable insulation is intact and in good condition to prevent catastrophic shorts.

“Improvements in test products include category safety ratings, beefier test leads with shielded probe tips, and extended reliability input protection are key features implemented over the past few years to make testing safer for electricians.

“The most common risks when making tests are not being aware of hazards category in the work area and not complying with the PPE and test tool safety rating required to work within that installation category. For example, a CAT III, 600V-rated meter has transient voltage protection and minimizes exposed lead tips to 4 mm to minimize the chances of arcing.

“For proper work methods and safety considerations, electrical workers should have formal training and apprenticeship from an accredited organization. Employers should provide safe work procedures and additional routine safety training sessions, such as lockout/tagout,” Gregorec said.

About the Author

Jeff Griffin

Construction Journalist

Jeff Griffin, a construction and tools writer from Oklahoma City, can be reached at

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