PC Safety Practices & Risk Management 3 — Questions and Answers
Question 1: Which personal protective equipment (PPE) category under NFPA 70E requires an arc rating of at least 40 cal/cm²?
- Category 4 (Correct answer)
- Category 1
- Category 2
- Category 3
Correct answer: Category 4
NFPA 70E PPE Category 4 requires arc-rated clothing and equipment with a minimum arc rating of 40 cal/cm².
Question 2: What is the purpose of an equipotential bonding jumper in electrical safety?
- To eliminate voltage differences between conductive parts that could cause shock (Correct answer)
- To increase current capacity of a feeder
- To provide a path for fault current to the service panel
- To ground neutral conductors at transformers
Correct answer: To eliminate voltage differences between conductive parts that could cause shock
Equipotential bonding connects conductive parts so no voltage difference exists between them, preventing shock hazards.
Question 3: Under OSHA 29 CFR 1926.416, unqualified workers must stay at least how far from overhead power lines under 50 kV?
- 10 feet (Correct answer)
- 5 feet
- 15 feet
- 3 feet
Correct answer: 10 feet
OSHA requires unqualified workers (and equipment) to maintain at least 10 feet from overhead power lines rated up to 50 kV.
Question 4: A Ground Fault Circuit Interrupter (GFCI) protects workers by:
- Tripping when it detects a current difference between hot and neutral conductors of as little as 5 mA (Correct answer)
- Shutting off power when a circuit overloads beyond its ampere rating
- Preventing voltage spikes from reaching sensitive equipment
- Automatically resetting after a short-circuit event
Correct answer: Tripping when it detects a current difference between hot and neutral conductors of as little as 5 mA
A GFCI monitors current imbalance between hot and neutral; a leakage as small as 4–6 mA triggers a trip in about 1/40th of a second.
Question 5: Which of the following best defines 'electrically safe work condition'?
- All energy sources are locked out, tested de-energized, and grounded as required (Correct answer)
- A qualified person is supervising the work at all times
- Work is performed outside during daylight hours
- Circuit breakers are in the off position but not locked out
Correct answer: All energy sources are locked out, tested de-energized, and grounded as required
An electrically safe work condition requires isolation, lockout, verification of de-energization, and grounding per NFPA 70E Article 120.
Question 6: Which type of ladder is prohibited for use by electricians working near energized equipment?
- Metal (aluminum or steel) ladders (Correct answer)
- Fiberglass ladders
- Wood ladders
- Composite non-conductive ladders
Correct answer: Metal (aluminum or steel) ladders
Metal ladders conduct electricity and must never be used near energized electrical equipment or conductors.
Question 7: What information must an arc flash hazard label on electrical equipment include per NFPA 70E?
- Nominal system voltage, arc flash boundary, and required PPE level or incident energy (Correct answer)
- Circuit breaker ampere rating and interrupting capacity
- Manufacturer name, model number, and installation date
- Panel schedule reference and feeder conductor size
Correct answer: Nominal system voltage, arc flash boundary, and required PPE level or incident energy
NFPA 70E Section 130.5(H) requires labels to show voltage, arc flash boundary, and either incident energy or PPE category.
PC Safety Practices & Risk Management 3
Which personal protective equipment (PPE) category under NFPA 70E requires an arc rating of at least 40 cal/cm²?