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Quizzes on the Code

Nov 1, 2002 12:00 PM, By Mike Holt, NEC Consultant

Choose the best answer:

1. An additional disconnecting means isn't required on or at the building or structure for the generator feeder conductors when an outdoor-housed generator supplying emergency circuits is equipped with a readily accessible disconnecting means that's located within sight of the building or structure supplied.
   (a) true
   (b) false

2. Where an outdoor-housed generator supplying legally required circuits is equipped with a readily accessible disconnecting means located within sight of the building or structure supplied, an additional disconnecting means isn't required on or at the building or structure for the generator feeder conductors.
   (a) true
   (b) false

3. Where acceptable to the authority having jurisdiction (AHJ), connections ahead of and not within the same cabinet, enclosure, or vertical switchboard section as the service disconnecting means are permitted for _____ standby service.
   (a) emergency
   (b) legally required
   (c) optional
   (d) all of these

4. Art. 702 applies to _____ generators.
   (a) fixed
   (b) portable
   (c) a and b
   (d) none of these

5. A transfer switch is required for all fixed or portable optional standby power systems for buildings or structures for which an electric-utility supply is either the normal or standby source.
   (a) true
   (b) false

6. If the transfer switch for a portable generator switches the _____ conductor, then the portable generator must be grounded in accordance with 250.30.
   (a) phase
   (b) equipment grounding
   (c) grounded (neutral)
   (d) all of these

7. If the transfer switch for a portable generator doesn't switch the _____ conductor, then the equipment-grounding conductor must be bonded to the system-grounding electrode.
   (a) phase
   (b) equipment grounding
   (c) grounded (neutral)
   (d) all of these

Answers and Discussion

1. (a), true. The new wording in 700.12(B)(6) clarifies that a disconnect for the feeder from a generator isn't required at or on the building or structure if the emergency generator disconnecting means is within sight of the building or structure. See Art. 100 for the definition of “in sight.”

2. (a), true. The new wording in 701.11(B)(5) clarifies that a disconnect for the feeder from a generator isn't required at or on the building or structure if the emergency generator disconnecting means is within sight of the building or structure. See Art. 100 for the definition of “in sight.”

3. (b), legally required. The revised wording in 701.11(E) clarifies that where acceptable to the AHJ, connections ahead of and not within the same cabinet, enclosure, or vertical switchboard section with the service disconnecting means may supply legally required standby power.

4. (c), a and b. A new sentence in 702.1 clarifies that Art. 702 applies to portable generators, which are commonly used for telecommunications facilities, water and waste water pump stations, and backup power to homes and offices.

5. (a), true. The Code now requires a transfer switch whenever a fixed or portable standby generator is connected to premises wiring (702.6).

6. (c), grounded (neutral). This means that the neutral of the portable generator must be bonded to the generator case and grounding electrode in accordance with 250.30 [702.10(A)].

7. (c), grounded (neutral). This means that the grounded (neutral) conductors of the generator may not be bonded to the case (250.142), but the case must be bonded to a system-grounding electrode. However, the grounding electrode system for the building can be used for this purpose [702.10(B)].

Are you still confused by the Code? For additional information on Code-related topics please visit www.mikeholt.com or send an e-mail directly to the author at mike@mikeholt.com.

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