CEI Emergency & Standby Systems 2 — Questions and Answers
Question 1: According to NEC Article 700, how quickly must emergency lighting systems restore illumination after normal power fails?
- Within 5 seconds
- Within 10 seconds (Correct answer)
- Within 30 seconds
- Within 60 seconds
Correct answer: Within 10 seconds
NEC 700.12 requires emergency lighting to be restored within 10 seconds of normal power failure.
Question 2: Which NEC article governs legally required standby systems?
- Article 700
- Article 701 (Correct answer)
- Article 702
- Article 703
Correct answer: Article 701
NEC Article 701 covers legally required standby systems, which are distinct from emergency systems in Article 700.
Question 3: A transfer switch for an emergency system must be located:
- In the main electrical room only
- As close as practicable to the loads served (Correct answer)
- Adjacent to the utility meter
- In a separate locked enclosure away from normal power
Correct answer: As close as practicable to the loads served
NEC 700.12 requires transfer equipment to be located as close as practicable to the emergency loads it serves.
Question 4: What is the minimum duration an emergency lighting unit battery must supply power under NEC Article 700?
- 30 minutes
- 1 hour and 30 minutes
- 2 hours (Correct answer)
- 4 hours
Correct answer: 2 hours
NEC 700.12(A) requires unit equipment batteries to maintain emergency illumination for a minimum of 1.5 hours — but the code-required duration for the system overall is 1.5 hours; unit equipment must supply power for 1.5 hours; the full system minimum is 1½ hours.
Question 5: Under NEC 700.10, emergency system wiring must be kept entirely independent of other wiring EXCEPT when:
- Both circuits use the same conduit to save cost
- Both circuits are in separate raceways within the same enclosure (Correct answer)
- Transfer switches permit combined routing after the load side
- The AHJ grants a blanket waiver
Correct answer: Both circuits are in separate raceways within the same enclosure
NEC 700.10(B) allows emergency and normal wiring to share an enclosure only if they are in separate raceways or separated by a barrier.
Question 6: Which type of generator connection is prohibited for an emergency system unless listed for that use?
- Automatic transfer switch
- Manual transfer switch
- Cord-and-plug connection (Correct answer)
- Solid-state transfer switch
Correct answer: Cord-and-plug connection
Cord-and-plug connections are not permitted for emergency system generators unless the equipment is specifically listed for that application.
Question 7: An emergency generator used for a hospital emergency system must have fuel storage sufficient to run the generator for at least:
- 4 hours at full load
- 8 hours at full load
- 24 hours at full load (Correct answer)
- 72 hours at full load
Correct answer: 24 hours at full load
NFPA 110 and NEC 700.12(B) require on-site fuel storage for a minimum of 2 hours for most occupancies, but healthcare facilities (NFPA 99) require fuel for at least 24 hours.
CEI Emergency & Standby Systems 2
According to NEC Article 700, how quickly must emergency lighting systems restore illumination after normal power fails?