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Quizzes on the Code

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

Choose the best answer:

1. Portable battery-operated devices like cordless drills and cell phones must be listed for use in a hazardous classified location, and the equipment must comply with the requirements of Chapter 5.

   (a) true
   (b) false

2. You must install a sealing fitting within _____ ft of either side of the boundary where a conduit leaves a Class I, Div. 1 location.

   (a) 6
   (b) 8
   (c) 10
   (d) 12

3. Where the Class I, Div. 1 boundary is beneath the ground, you must install the sealing fitting _____.

   (a) after the conduit leaves the ground
   (b) before the conduit leaves the ground
   (c) within 10 ft
   (d) none of these

4. You can install multiwire branch-circuits in a Class I, Zone 1 location if you can open ungrounded (hot) conductors of the multiwire circuit simultaneously.

   (a) true
   (b) false

5. The requirements in Art. 511 apply to locations used for service and repair operations in connection with self-propelled vehicles like _____, in which volatile flammable liquids or flammable gases are used for fuel or power.

   (a) buses
   (b) trucks
   (c) tractors
   (d) all of these

6. The floor area of a commercial garage, repair, or storage facility shall not be classified if the enforcing agency determines that there is mechanical ventilation that provides a minimum of four air changes per hour or _____ cu ft per min of exchanged air for each square foot of floor space.

   (a) 1
   (b) 2
   (c) 3
   (d) 4

7. Where CNG vehicles are repaired or stored, the area within _____ in. of the ceiling shall be classified as Class I, Div. 2, except where ventilation of at least four air changes per hour is provided.

   (a) 6
   (b) 12
   (c) 18
   (d) 24

8. Each dispensing device in a motor fuel dispensing facility must be provided with a means to remove all external voltage sources, including feedback, during periods of maintenance and service of the dispensing equipment. The disconnecting means must be either inside or adjacent to the dispensing device.

   (a) true
   (b) false

Answers and Discussion

1. (b), false. The NEC is an installation standard, so battery-operated equipment doesn't fall within its scope. The FPN to the new definition of electrical and electronic equipment (500.2) was added to alert Code users that portable or transportable devices such as battery-powered tools and equipment could potentially become ignition sources in a hazardous location. However, FPNs are not enforceable [90.5(C)].

2. (c), 10. Sec. 501.5(A)(4) specifies where a seal is required for general applications in conduit runs leaving a Class I, Div. 1 location. The seal fitting must be designed and installed so it minimizes the amount of gas or vapor communicated beyond the seal of the Div. 1 portion of the conduit.

3. (a), after the conduit leaves the ground. A new Exception to 501.5(A)(4) clarifies where a seal fitting can be installed for underground conduit runs leaving a Class I, Div. 1 location. Except for listed explosion-proof reducers at the conduit seal, there must be no union, coupling, box, or fitting between the conduit seal and the point where the conduit leaves the ground.

4. (a), true. This installation is acceptable per 505.21.

5. (d), all of these. Text was added to 511.1 to clarify that its requirements also apply to garages that repair vehicles powered by flammable gases, such as compressed natural gas (CNG), in addition to volatile flammable liquids like gasoline.

6. (a), 1. Sec. 511.3(B)(1) was significantly changed to clarify the Exception for determining what is adequate ventilation to change a Class I, Div. 2 location to an unclassified area.

7. (c), 18. A new subsection [511.3(B)(2)] to Art. 511 expands the locations of classified areas for compressed natural gas. The area within 18 in. of the ceiling is to be classified as a Class I, Div. 2 location. Some AHJs might require all wiring within 18 in. of the ceiling to be made suitable for Class 1, Div. 1 locations, in accordance with 501.4.

8. (b), false. The revised text in 514.13 clarifies that the maintenance disconnect for the dispensing equipment isn't required to be part of, or adjacent to, the dispenser.

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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