E2 Safety Standards and Practices 3 — Questions and Answers
Question 1: Which standard governs electrical safety in the workplace for general industry, separate from construction sites?
- OSHA 29 CFR 1910 Subpart S (Correct answer)
- OSHA 29 CFR 1926 Subpart K
- NFPA 70B
- ANSI Z10
Correct answer: OSHA 29 CFR 1910 Subpart S
OSHA 29 CFR 1910 Subpart S covers electrical safety in general industry workplaces, while 1926 Subpart K applies to construction.
Question 2: A commercial electrical inspector finds a 600A, 480V panelboard installed in a boiler room with ambient temperatures regularly reaching 45°C. What is the primary concern?
- Overcurrent devices are rated at 40°C; derating is required above that temperature (Correct answer)
- All panelboards are rated for up to 75°C ambient without derating
- The breakers must be replaced with fuses at elevated temperatures
- Only service entrance equipment requires temperature derating
Correct answer: Overcurrent devices are rated at 40°C; derating is required above that temperature
Most overcurrent protective devices are rated at 40°C ambient; sustained higher temperatures require derating per manufacturer specifications and NEC guidelines.
Question 3: Under NFPA 70E, an electrically safe work condition is verified by which sequence of steps?
- De-energize, lockout/tagout, test for absence of voltage, apply grounds if needed (Correct answer)
- Test for voltage, de-energize, apply grounds, then lockout
- Apply PPE, de-energize, test, then lockout/tagout
- Lockout first, then de-energize, then test for absence of voltage
Correct answer: De-energize, lockout/tagout, test for absence of voltage, apply grounds if needed
NFPA 70E 120.5 requires de-energizing, applying LOTO, then testing for absence of voltage before establishing an electrically safe work condition.
Question 4: An inspector notices a commercial generator transfer switch with no bonding jumper between the generator neutral and the grounding electrode system. This violates which NEC section?
- NEC 250.30 for separately derived systems (Correct answer)
- NEC 230.95 for ground fault protection
- NEC 700.10 for emergency circuits
- NEC 445.13 for generator conductor ampacity
Correct answer: NEC 250.30 for separately derived systems
NEC 250.30 requires that a separately derived system, such as a generator, have a system bonding jumper and be connected to a grounding electrode.
Question 5: A commercial site uses a qualified person to perform energized electrical work. NFPA 70E requires this person to have documented training in which areas at minimum?
- Skills and techniques to distinguish exposed live parts, work on or near exposed live parts, and PPE selection (Correct answer)
- Only PPE selection and emergency first aid procedures
- Lockout/tagout procedures and fire extinguisher use only
- Voltage testing and equipment manufacturer training only
Correct answer: Skills and techniques to distinguish exposed live parts, work on or near exposed live parts, and PPE selection
NFPA 70E defines a qualified person as one trained in skills to distinguish live parts, work safely near them, and properly select and use PPE.
Question 6: According to NEC 230.70, the main service disconnecting means for a commercial building must be located:
- Outside the building or inside nearest the point of service entrance (Correct answer)
- In the electrical room on the top floor only
- Within 30 feet of the utility meter
- At the load center closest to the largest load
Correct answer: Outside the building or inside nearest the point of service entrance
NEC 230.70(A)(1) requires the service disconnecting means to be located outside or inside the building nearest the point of entrance of service conductors.
Question 7: When an E2 inspector encounters an ungrounded 480V delta system in a commercial facility, which safety device is specifically required by NEC 230.95 for service conductors 150V to ground or less?
- Ground fault protection of equipment (GFPE) is not required since the system is ungrounded (Correct answer)
- GFPE set at 1200A is required for all 480V delta systems
- GFCI protection at every receptacle on the system
- Ground fault relay with instantaneous trip only
Correct answer: Ground fault protection of equipment (GFPE) is not required since the system is ungrounded
NEC 230.95 requires GFPE only for solidly grounded wye services of more than 150V to ground but not exceeding 600V phase-to-phase; ungrounded delta systems are exempt.
E2 Safety Standards and Practices 3
Which standard governs electrical safety in the workplace for general industry, separate from construction sites?