Right Tool for the Right Job: Choose the correct electrical safety testing device

Electrical testing devices are a critical part of performing electrical work and ensuring the safety of all. Whether complying with the de-energization requirements of the Occupational Safety and Health Administration or NFPA 70E, Standard for Electrical Safety in the Workplace, or working energized under their few exceptions, testers are a must. Electrical workers need to make sure they have the right tool for the job, and that it is in good working order and is used properly.

Not surprising is that in a survey of electricians on the most essential items in their tool bag, the following testers were on the list: noncontact voltage tester, clamp meter, insulation tester, fluorescent light tester, earth ground tester and multimeter. Standing out above the pack is the multimeter. It not only provides a look at multiple testing functions, but it serves as a great example for reviewing considerations on selection, care and use of testing equipment as a whole.

Before looking at these considerations, you must address worker qualification and personal protective equipment (PPE). Only a qualified person should use a tester. A qualified person is defined by NFPA 70E as “one who has demonstrated skills and knowledge related to the construction and operation of electrical equipment and installations and has received safety training to identify the hazards and reduce the associated risk.”

The person must know how to work on that specific installation and all the equipment involved, including the test equipment. They must also be wearing all required PPE, even when using the test equipment during de-energization. Remember, until the circuit and equipment are confirmed de-energized, the same risk potential exists as if working energized. A shock and arc flash assessment must be done to identify the necessary PPE.

The next step is selecting the right tester for the job. For example, if testing for the absence of voltage, a noncontact or proximity tester may serve well for high-voltage systems, an initial test or early warning of hidden energized conductors or parts, but not for confirmation. NFPA 70E requires testing phase-to-phase and phase-to-ground with limited exceptions, such as systems over 1,000V. Noncontact voltage testers can only test phase-to-ground.

Job considerations go beyond just the type of tester. All parameters need to be known and considered. Here, again, multitesters offer insight into the breadth of the scope of parameters and applicability to selection. Three ratings to note include overvoltage installation category (CAT II, CAT III or CAT IV), ingress protection (IP) levels (0–8 for water and 0–6 for particles) and voltage. Using a CAT II-600 tester to measure a 480V electrical distribution feeder panel may meet voltage requirements, but not category. A CAT III-600V, CAT III-1,000V or CAT IV-600V could work for the job. Similarly, a tester with a 0 IP for particle should not be used in a dusty environment. Not knowing what standards equipment must meet and apply to the testing to be performed can be fatal.

After selecting the tester, ensure it is in proper working order. Prior to use, it needs to be inspected. During inspection, it is important to ensure there are no obvious defects in the case or meter element, the selector switch turns smoothly without binding, the functions change properly when the selector switch is operated, the tester has the correct rating for the part of the electrical system it is being used on and the display functions are working properly.

The device should also be calibrated. A calibration certificate may be required if the work is under ISO 9000, FDA regulated, government contracting or by one of the many companies that require traceability of measurements.

Additionally, the test leads need to be inspected for any signs of damage, such as cuts or breaks in the insulation, melted or discolored insulation or crushing of the test lead. Crushing could indicate that there is internal damage. It is also imperative to ensure the probe ends are tight, straight and undamaged. Burnt or loose probe ends could be an indicator the device is not working properly.

Finally, follow all best practices for using testing equipment. At the top of the list for determining absence of voltage is the live-dead-live practice. NFPA 70E describes this as “Operation Verification….for testing the absence of voltage on conductors or circuit parts operating at voltages equal to or greater than 50V, the operation of the test instrument shall be verified on any known voltage source before and after an absence of voltage test is performed.”

Following this and any other electrical protocols prescribed by NFPA 70E, OSHA and other safety standards will save lives.

About the Author

Tom O'Connor

Safety Columnist

Tom O'Connor is safety and regulatory affairs manager for Intec, a safety consulting, training and publishing firm that offers on-site assistance and produces manuals, training videos and software for contractors. Reach him at toconnor@intecweb.com.

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