Safety and PPE Flashcards

A technician is performing infrared thermography on energized 15 kV switchgear with an incident energy level calculated at 28 cal/cm². The available PPE kit includes an arc flash suit rated at 25 cal/cm² and a face shield rated at 40 cal/cm². Which action is correct?

Answer: Do not proceed — the arc flash suit rating is insufficient for the calculated incident energy

Per NFPA 70E, ALL PPE components worn must individually meet or exceed the calculated incident energy. The arc flash suit at 25 cal/cm² is below the 28 cal/cm² incident energy — it is not code-compliant regardless of the task type or other PPE ratings. The only correct action is to obtain a properly rated suit or re-engineer the task to reduce exposure.

During a NETA acceptance test on a 480 V panelboard, the ground fault current path is broken and the equipment grounding conductor reads 8 ohms to the source neutral. Under NFPA 70E's approach boundary model, which boundary is most directly affected by this grounding deficiency?

Answer: Arc flash boundary, because fault clearing time increases when ground path impedance is high

A high-impedance ground fault return path means overcurrent protective devices will take longer — or may fail — to clear a fault. Longer arcing duration directly increases incident energy, which pushes the arc flash boundary outward. The arc flash boundary is the boundary most dynamically sensitive to fault clearing time, making choice A correct.

A NETA technician is working under an Energized Electrical Work Permit on 2.4 kV equipment classified as Hazard/Risk Category (HRC) 3. The technician's arc-rated balaclava is rated at 12 cal/cm² and their arc-rated gloves are rated at 8 cal/cm². The incident energy at the working distance is 17 cal/cm². Which statement is accurate?

Answer: Both the balaclava and gloves are individually non-compliant with the incident energy level

NFPA 70E requires each individual piece of arc-rated PPE to meet or exceed the calculated incident energy (17 cal/cm²). The balaclava at 12 cal/cm² and gloves at 8 cal/cm² both fall short — neither is compliant. There is no 'system average' exception, and voltage class does not exempt gloves from arc rating requirements.

When using a clamp-on current transformer to test a 5 kV cable in a vault, a technician notices the cable jacket is visually intact but the cable dates from 1971. Which safety consideration is MOST specific to NETA Maintenance Testing Standard (MTS) procedures for aged medium-voltage cables?

Answer: Treat the cable as potentially having insulation degraded beyond its original rating and verify dielectric withstand before any energized work

NETA MTS and ANSI/IEEE standards emphasize that aged cables — particularly pre-1980 paper-insulated lead-covered (PILC) or early XLPE — may have insulation integrity far below nameplate rating due to moisture ingress, thermal cycling, and oxidation. Before any energized contact or clamping, the technician must verify dielectric withstand to establish a safe working assumption about the cable's actual insulation state.

A technician performing NETA testing on a large UPS system bypasses the UPS to a static bypass source and begins testing the inverter section. A co-worker de-energizes what is believed to be the correct breaker upstream, but a backfeed path exists through the battery DC bus. Which lockout/tagout (LOTO) concept does this scenario specifically violate?

Answer: Verification of zero energy state — all energy sources including stored energy must be isolated and verified

OSHA 29 CFR 1910.147 and NFPA 70E both require that ALL energy sources — including stored energy such as capacitor banks and battery systems — be isolated, blocked, or dissipated, and then verified at zero energy before work begins. The battery DC bus represents a stored energy source that was not isolated. Simply de-energizing an upstream breaker is insufficient when backfeed paths exist.

A NETA technician must perform an insulation resistance test on a 13.8 kV motor that was last tested 3 years ago and showed an IR value of 1,200 MΩ. Today's test reads 180 MΩ at the same temperature. Using the polarization index (PI) and the NETA MTS threshold for acceptance, which assessment is correct?

Answer: The trend indicates insulation degradation; NETA MTS requires investigating the cause before returning the motor to service

NETA MTS emphasizes trending IR values over time as the most meaningful diagnostic indicator. While 180 MΩ may exceed a single-point minimum, an 85% reduction from a prior baseline (1,200 MΩ → 180 MΩ) represents a significant downward trend that NETA MTS flags as requiring investigation. PI and DAR are same-session calculations and do not apply across multi-year records; the trend analysis is the operative NETA tool here.