EETC Electrical Safety & Code Compliance 3 — Questions and Answers
Question 1: Which NFPA 70E category of arc flash PPE requires a minimum arc rating of 40 cal/cm²?
- PPE Category 1
- PPE Category 2
- PPE Category 3
- PPE Category 4 (Correct answer)
Correct answer: PPE Category 4
NFPA 70E PPE Category 4 requires a minimum arc rating of 40 cal/cm², the highest standard category for arc flash protection.
Question 2: An electrical worker is injured by an arc flash. The incident energy at the working distance was 8 cal/cm². Which PPE category was MINIMALLY required?
- PPE Category 1 (4 cal/cm²)
- PPE Category 2 (8 cal/cm²) (Correct answer)
- PPE Category 3 (25 cal/cm²)
- PPE Category 4 (40 cal/cm²)
Correct answer: PPE Category 2 (8 cal/cm²)
NFPA 70E PPE Category 2 covers incident energy up to 8 cal/cm², so Category 2 PPE would minimally satisfy this scenario.
Question 3: What color is assigned to the high-voltage warning label per ANSI Z535 standards?
- Blue
- Orange (Correct answer)
- Yellow
- Red with orange border
Correct answer: Orange
ANSI Z535 assigns orange to warning signs indicating hazardous conditions (including high voltage) that could cause serious injury.
Question 4: The NEC defines a 'qualified person' for electrical work as someone who:
- Holds a master electrician license
- Has completed an apprenticeship program
- Has training and experience on electrical equipment and hazards (Correct answer)
- Has passed OSHA 10 certification
Correct answer: Has training and experience on electrical equipment and hazards
NEC Article 100 defines a qualified person as one with skills and knowledge of construction/operation of equipment and the hazards involved.
Question 5: Which type of grounding electrode is considered the MOST effective per NEC 250.52?
- Ground rod
- Metal water pipe
- Concrete-encased electrode (Ufer ground) (Correct answer)
- Plate electrode
Correct answer: Concrete-encased electrode (Ufer ground)
The concrete-encased electrode (Ufer ground) provides the most reliable low-impedance earth connection due to contact with moist concrete.
Question 6: A technician discovers a conductor with insulation rated at 60°C installed in a conduit where ambient temperature reaches 50°C. What is the primary concern?
- The conductor will corrode faster
- The ampacity is significantly derated, risking overheating (Correct answer)
- The insulation color will fade
- The conductor resistance increases permanently
Correct answer: The ampacity is significantly derated, risking overheating
High ambient temperature reduces the conductor's ability to dissipate heat, requiring ampacity derating per NEC 310 correction factors.
Question 7: According to NEC 230.79, the minimum service entrance conductor ampacity for a single-family dwelling is:
- 60 amperes
- 100 amperes (Correct answer)
- 150 amperes
- 200 amperes
Correct answer: 100 amperes
NEC 230.79(C) requires a minimum 100-ampere service for a single-family dwelling with more than one branch circuit.
EETC Electrical Safety & Code Compliance 3
Which NFPA 70E category of arc flash PPE requires a minimum arc rating of 40 cal/cm²?