ASP Electrical Safety 1 — Questions and Answers
Question 1: According to NFPA 70E, what is the primary purpose of an arc flash hazard analysis?
- To determine the incident energy at a worker's position and select appropriate PPE (Correct answer)
- To identify the number of electrical panels in a facility
- To calculate the total electrical load on a circuit
- To establish the minimum wire gauge for branch circuits
Correct answer: To determine the incident energy at a worker's position and select appropriate PPE
An arc flash hazard analysis determines the incident energy level at a worker's working distance so that appropriate arc-rated PPE can be selected.
Question 2: Under OSHA 29 CFR 1910.333, a 'qualified worker' performing electrical work must demonstrate which of the following?
- Ability to avoid hazards of working on or near exposed energized parts (Correct answer)
- A minimum of 10 years of electrical experience
- Possession of a licensed electrician certificate in the state
- Completion of an OSHA 30-hour course
Correct answer: Ability to avoid hazards of working on or near exposed energized parts
OSHA defines a qualified person as one who has training and experience to recognize and avoid the electrical hazards present in energized work.
Question 3: What effect does an alternating current (AC) of approximately 100–300 mA have on the human body?
- Ventricular fibrillation and likely death (Correct answer)
- Mild tingling sensation only
- Muscle contractions preventing release but no cardiac effect
- No perceptible effect
Correct answer: Ventricular fibrillation and likely death
Currents in the 100–300 mA range passing through the chest are sufficient to cause ventricular fibrillation, which is often fatal without immediate defibrillation.
Question 4: Which OSHA standard governs electrical safety-related work practices for general industry?
- 29 CFR 1910.331–.335 (Correct answer)
- 29 CFR 1910.147
- 29 CFR 1926.404
- 29 CFR 1910.120
Correct answer: 29 CFR 1910.331–.335
OSHA 29 CFR 1910.331–.335 (Subpart S) covers electrical safety-related work practices for general industry workers.
Question 5: A Ground Fault Circuit Interrupter (GFCI) is designed to trip when it detects a ground fault current exceeding:
- 4–6 milliamperes (Correct answer)
- 15 amperes
- 20 milliamperes
- 1 ampere
Correct answer: 4–6 milliamperes
GFCIs are designed to trip at 4–6 mA of ground fault current, a level below the threshold for serious injury, protecting people from electrocution.
Question 6: The Limited Approach Boundary defined by NFPA 70E is the distance from an energized conductor within which:
- An unqualified person may not cross without being escorted and briefed on electrical hazards (Correct answer)
- Only PPE Category 4 equipment must be worn
- All electrical work must stop immediately
- A qualified worker must use rubber gloves at all times
Correct answer: An unqualified person may not cross without being escorted and briefed on electrical hazards
The Limited Approach Boundary is the closest distance an unqualified person may approach unless escorted by a qualified person and aware of the hazards.
Question 7: When performing lockout/tagout on electrical equipment, what must be verified AFTER energy isolation?
- That the equipment cannot be energized by testing with an approved voltage tester (Correct answer)
- That a safety tag has been placed on the disconnect
- That a second lock has been applied by a supervisor
- That the circuit breaker has been removed from the panel
Correct answer: That the equipment cannot be energized by testing with an approved voltage tester
Verification of de-energization using an approved voltage tester is required to confirm the energy isolation was successful before work begins.
