Safety and PPE Flashcards

A NETA technician is preparing to perform infrared thermography on energized switchgear with a calculated incident energy of 22 cal/cm² at the working distance. The technician has PPE Category 3 gear rated at 25 cal/cm² arc rating. Which statement best describes the correct course of action under NFPA 70E?

Answer: The Category 3 PPE is acceptable because its arc rating exceeds the calculated incident energy.

NFPA 70E requires that the arc rating of the PPE system equal or exceed the calculated incident energy. At 22 cal/cm², Category 3 PPE with a 25 cal/cm² arc rating is sufficient — the arc rating exceeds the incident energy. There is no rule requiring Category 4 simply because energy is above 20 cal/cm²; the threshold for Category 4 is incident energy above 25 cal/cm². PPE categories set minimum ratings, not exact thresholds.

According to ASTM F496, rubber insulating gloves that are used daily in the field must be electrically retested at what maximum interval, and what must happen if a glove has not been electrically tested within the past 12 months?

Answer: Every 6 months when in service; gloves must not be used in service until they have been electrically retested.

ASTM F496 requires that rubber insulating gloves in service be electrically tested every 6 months. Additionally, if a glove has not been electrically tested within the past 12 months — regardless of whether it was used — it must not be returned to service until it passes a new electrical test. Visual inspection and air inflation check are daily user checks but do not substitute for the electrical retest requirement.

During a complex LOTO sequence on a piece of equipment with both electrical and hydraulic stored energy, a NETA technician correctly de-energizes and locks out the electrical source, then drains and blocks the hydraulic system. When verifying absence of voltage with a test instrument, the instrument reads zero. What is the most critical step the technician has likely omitted before touching exposed electrical conductors?

Answer: Verifying the test instrument's functionality on a known live source before and after testing the isolated conductors.

NFPA 70E and safe electrical testing practice require verification of the test instrument's proper operation on a known energized source both before and after testing the de-energized conductors. This live-dead-live check confirms the instrument is working correctly and didn't fail mid-test. A failed or damaged instrument could falsely indicate zero voltage, leading to contact with an energized conductor. Skipping this step is one of the most common and dangerous procedural omissions.

A technician is applying temporary protective grounds on a de-energized 15 kV distribution feeder for maintenance work. The feeder has been isolated and tested as de-energized. What is the correct sequence for attaching and removing the temporary grounds?

Answer: Attach to the grounding electrode first, then to the phase conductors; remove from the phase conductors first, then from the grounding electrode.

IEEE 1246 and OSHA 1910.269 specify that protective grounds must be attached to the grounding electrode (earth) first, then clipped to the phase conductors. This sequence ensures the clamp is already bonded to ground before it touches the conductor — so if the line were inadvertently energized during the attachment process, fault current flows to ground rather than through the worker. On removal, the phase conductors are disconnected first (earth bond removed last), for the same reason in reverse.

A NETA technician is working within the restricted approach boundary of 480V energized bus during an infrared inspection. The technician is wearing Class 00 rubber insulating gloves (rated 500V AC maximum use voltage). Which condition makes this glove selection a violation?

Answer: The actual transient overvoltages on a 480V system can exceed 500V, making Class 00 gloves inadequate for the system's withstand voltage exposure.

The 480V rating refers to nominal system voltage, but the Class 00 maximum use voltage (500V AC) is not evaluated against nominal voltage alone. NFPA 70E Table 130.7(C)(15)(c) and glove selection practice require considering the maximum phase-to-phase voltage including transient overvoltages. On a 480V nominal system, transient spikes — common during switching — can easily exceed 500V, which is the Class 00 limit. The appropriate choice for 480V work is Class 0 (rated 1,000V AC max use voltage), which provides adequate margin for transient conditions.

Under NFPA 70E, which scenario represents a valid justification for performing energized electrical work rather than de-energizing the equipment first?

Answer: De-energizing the equipment would require a utility-coordinated outage affecting other customers, creating a greater hazard than the energized task.

NFPA 70E 130.2(A) permits energized electrical work only under two conditions: (1) de-energizing introduces additional or increased hazards (e.g., loss of ventilation in a hazardous atmosphere, loss of illumination in a dark confined space, or — as in this case — an outage that affects safety-critical systems or causes greater hazard to others), or (2) de-energizing is infeasible due to equipment design or operational limitations. Production inconvenience or scheduling preference does not qualify. An energized work permit is task-specific and date-bound — it cannot be reused for a different task.