Safety and PPE Flashcards

A technician is performing infrared thermography on energized switchgear rated at 480V. The arc flash hazard analysis indicates an incident energy of 8.2 cal/cm². Which PPE ensemble is the MINIMUM required?

Answer: Arc flash suit rated for at least 8.2 cal/cm² with an arc-rated balaclava and face shield with the same rating

Per NFPA 70E, PPE must meet or exceed the calculated incident energy — in this case 8.2 cal/cm². A suit rated at exactly 8 cal/cm² (answer A) would be insufficient. All arc-rated components — including the balaclava and face shield — must carry a rating equal to or greater than the incident energy. FR clothing alone (answer C) is not adequate for arc flash above 1.2 cal/cm². Defaulting to Category 4 (answer D) is not required and wastes resources; the hazard analysis governs.

During a substation acceptance test, a technician must establish an Electrically Safe Work Condition (ESWC) on a 15 kV bus. After opening the disconnect and verifying absence of voltage with an approved tester, the technician skips applying personal protective grounds because 'the bus feeds a single transformer that is confirmed de-energized.' What NETA/OSHA-recognized hazard does this action overlook?

Answer: Induced voltage from adjacent energized conductors running in parallel

Even with the source confirmed de-energized, long parallel runs of conductors in a substation can develop hazardous induced voltages from adjacent energized circuits through electromagnetic coupling. Personal protective grounds (PPGs) provide a low-impedance path that prevents this induced energy from appearing across the worker. OSHA 1910.269 and NETA safety standards mandate grounds be applied regardless of source verification for this reason. Capacitive discharge from the transformer (answer C) dissipates quickly after de-energization and is addressed by the absence-of-voltage test itself.

A NETA technician is using a Category III–rated clamp meter (1000V CAT III) to measure current on a 480V feeder inside a motor control center (MCC). A colleague suggests the CAT III rating means the meter is safe for any measurement at that MCC. Which statement BEST describes the flaw in that reasoning?

Answer: The CAT rating addresses impulse transient withstand, not steady-state voltage; the MCC's available fault current may exceed the meter's interrupting rating

IEC 61010 CAT ratings describe a meter's ability to withstand voltage transients (impulses) at a given installation category — they do not directly limit the continuous voltage or the available short-circuit current at the measurement point. Inside a large MCC, the prospective fault current can be tens of kiloamps. If the meter's interrupting/breaking rating is exceeded during a fault event, the meter can fail violently. The technician must verify the meter's interrupting rating against the available fault current of the circuit, not just the CAT level and voltage rating. The other answers are incorrect: CAT ratings apply to all phases, clamp meters are perfectly appropriate for current measurement, and there is no separate 'CAT IV face shield' requirement triggered by meter category.

A technician establishes an ESWC on a 4.16 kV vacuum circuit breaker and applies personal protective grounds. While working inside the breaker compartment, a second crew member is dispatched to re-energize an adjacent feeder on the same bus. Under the multi-employer worksite rules applicable to NETA field work, what is the FIRST required action before the adjacent feeder is re-energized?

Answer: Re-energization must be coordinated through a common lockout/tagout (LOTO) authority, and the first technician must be physically clear of the hazard zone and account for their personal grounds

OSHA 1910.147 and 1910.269, along with NFPA 70E, require that under a multi-employer LOTO scenario all affected employees must be accounted for and all personal protective equipment (grounds and locks) removed or repositioned before re-energization. A verbal notification alone (answer A) does not satisfy the control verification requirement. Removing grounds only from the 'other' feeder (answer B) ignores that bus coupling could re-energize the work zone. Posting an observer (answer D) provides no actual energy isolation. The controlling LOTO authority must confirm worker clearance and ground removal before any switch operation proceeds.

Which condition would render a voltage-rated insulated hand tool (rated 1000V per IEC 60900) UNSAFE for continued use, even if it shows no visible cracks?

Answer: The tool is beyond its manufacturer-recommended service life or re-test interval, and no current calibration sticker is affixed

IEC 60900 and ASTM F1505 require that insulated tools be periodically retested (typically every 12 months) and that the tool carry a current test sticker. A tool beyond its re-test interval cannot be assumed safe even if it passes a visual inspection, because dielectric aging, micro-cracking, and contamination may not be visible yet can dramatically reduce withstand voltage. Low-temperature storage (answer A) is a concern for some materials but does not by itself make the tool unsafe. High humidity (answer B) is a use condition, not a permanent degradation. Withstanding 900V (answer C) is below the 1000V rating but may be an acceptable intermediate test level — this alone does not condemn the tool.

A NETA technician is working in a confined space (a cable vault) performing high-potential (HiPot) testing on 5 kV cables. Atmospheric testing at entry showed O₂ at 20.8%, LEL at 0%, and H₂S at 0 ppm. An hour into the work, the HiPot set discharges repeatedly into cable insulation failures. What previously acceptable atmospheric hazard must now be continuously monitored due to the HiPot activity?

Answer: Ozone (O₃), generated by corona and arc discharge from the HiPot set and cable breakdowns

High-voltage corona discharge and electrical arcing — both inherent to HiPot testing and especially prominent during repeated insulation breakdowns — produce ozone (O₃) from atmospheric oxygen. In a confined space with limited ventilation, ozone can accumulate to hazardous concentrations (OSHA PEL: 0.1 ppm, ACGIH TLV: 0.05–0.2 ppm depending on work intensity). This hazard is not present at entry but is generated by the work activity itself, making continuous atmospheric monitoring essential after HiPot activity begins. Carbon monoxide (answer A) is associated with combustion, not electrical discharge in this context. H₂S (answer C) is not liberated from XLPE by electrical stress. NO₂ (answer D) is produced by arc welding in nitrogen-rich atmospheres, not by a HiPot transformer.