CEP Safety Standards & Compliance 4 — Questions and Answers
Question 1: Which NEC article addresses the requirements for surge-protective devices (SPDs) installed on service entrance equipment?
- Article 285
- Article 230
- Article 250
- Article 280 (Correct answer)
Correct answer: Article 280
NEC Article 280 covers surge-protective devices (formerly 285 for SPDs), including requirements for those installed at service entrances.
Question 2: In a hazardous location classified as Class I, Division 1, what type of wiring method is required?
- Type NM cable (Romex)
- Threaded rigid metal conduit (RMC) or approved explosion-proof equipment (Correct answer)
- Flexible metal conduit only
- PVC conduit with sealed fittings
Correct answer: Threaded rigid metal conduit (RMC) or approved explosion-proof equipment
Class I, Division 1 locations require threaded RMC, steel intermediate metal conduit, or other NEC-approved methods with explosion-proof seals and fittings.
Question 3: According to OSHA 1926.416, what is the minimum safe approach distance for unqualified workers from unguarded, energized overhead power lines at 50kV?
- 6 feet
- 10 feet (Correct answer)
- 12 feet
- 15 feet
Correct answer: 10 feet
OSHA 1926.416 requires unqualified workers to maintain at least 10 feet from energized overhead lines up to 50kV; above 50kV the distance increases.
Question 4: What is the primary purpose of a main bonding jumper (MBJ) in an electrical service?
- To connect the grounding electrode to the utility transformer
- To connect the neutral (grounded conductor) to the equipment grounding system at the service point (Correct answer)
- To limit fault current to safe levels
- To provide a return path for lightning surges
Correct answer: To connect the neutral (grounded conductor) to the equipment grounding system at the service point
The main bonding jumper connects the neutral conductor to the equipment grounding conductor and the grounding electrode system at the service, enabling fault current to return and trip overcurrent devices.
Question 5: Under NEC 110.3(B), what is required after installing any listed electrical equipment?
- A third-party inspection within 30 days
- Installation and use must comply with the listing and labeling instructions (Correct answer)
- A load calculation must be submitted to AHJ
- A bond must be filed with the equipment manufacturer
Correct answer: Installation and use must comply with the listing and labeling instructions
NEC 110.3(B) requires that listed and labeled equipment be installed and used in accordance with any instructions included in the listing or labeling.
Question 6: Which of the following correctly describes a 'ground fault' in an electrical circuit?
- An overload condition where current exceeds the conductor's rating
- An unintended connection between an energized conductor and a grounded surface or earth (Correct answer)
- A short circuit between two phase conductors
- An open neutral creating voltage imbalance
Correct answer: An unintended connection between an energized conductor and a grounded surface or earth
A ground fault is an unintentional low-impedance connection between an energized conductor and grounded metal or earth, creating a fault current path.
Question 7: Per NFPA 70E 2021 edition, what is required before an employee enters a permit-required confined space containing electrical hazards?
- Only verbal authorization from a supervisor
- Established electrically safe work condition or specific written procedures for energized work (Correct answer)
- A written permit co-signed by the utility company
- Completion of a 40-hour confined space training course
Correct answer: Established electrically safe work condition or specific written procedures for energized work
NFPA 70E requires an electrically safe work condition or, if energized work is justified, a formal energized electrical work permit with documented safety procedures.
CEP Safety Standards & Compliance 4
Which NEC article addresses the requirements for surge-protective devices (SPDs) installed on service entrance equipment?