Fire & Life Safety: Pop Quiz on NEC Wiring Methods

Test yourself on National Electrical Code issues


Whether you are practicing for a fire alarm exam or just want to test yourself on wiring methods, try this quiz to test your knowledge of how to locate rules of adopted codes and standards. This test references the 2011 edition of the National Electrical Code.

You can answer these eight questions and then check your work in the “answers” section below them. Anyone can guess, but a pro both knows the rules and knows where those rules are located.

Question #1: If you fish NAC and IDC circuits from the basement of a two family condo, up to the second floor, do you need to use FPLP-rated cable?

Question #2: Your technician has extended the SLC loop from a manual pull box to add a smoke detector by drilling into the wall cavity above the ceiling grid, then, he fished the wire down about five feet to the manual pull box located in the same room now protected with the new addressable smoke detector. The technician didn’t make a hole through the fire-rated wall. Is he finished?

Question #3: An electrical contractor showed you some metal clips that push down onto the top of the T-bar used to hold the tiles on a suspended ceiling. These clips were made to hold the cables for his low-voltage track lighting system about four inches above the ceiling grid. Can you use these clips to keep the alarm cables off the tiles for the fire alarm system wiring?

Question #4: Your technician shows you his neat work with all the many cables bundled tightly together using nylon zip ties. You notice that not all the cables are actually running through the support rings, which are full; however, all cables are securely bundled and neat looking. What part of the NEC do you show him indicating the error he has made?

Question #5: Why is it that I seem to run across equipment and devices that don’t seem to meet the NEC requirements as they relate to fire alarm systems? Do the dry-wall boxes that have no backs, mud rings, and similar plaster rings I see being used by other low voltage contractors meet the NEC?
 

Question #6: Your technician points out that the mechanical contractor has tie-wrapped a four-conductor thermostat cable to the electrical conduit containing the 120 volt AC wiring powering an HVAC unit and wants to “say something” about it to him. Is the technician correct about this being a rather basic NEC violation?

Question #7: Can FPL wiring exit from a section of EMT or must it only exit through a box having a wire clamp and bushing?

Question #8: Your technician used a 7/8-inch paddle bit to drill through about 25 2x4 studs in order to run FPL wiring to a manual pull box and horn-strobe. Now he plans to install metal plates on about every other stud to protect the wiring from damage from nails and drywall screws. I thought the rule would apply to every stud, not half of them. The inspector says it should have been a smaller hole. What’s that have to do with every other stud needing a steel protective plate?

 

The Answers

#1: No. NEC section 760.154 states that the cable you use may be type FPL — “(3) Type FPL cable shall be permitted in one- and two family dwellings.” Save the FPLR for running wiring exposed (no conduit) in commercial buildings having more than two floors.

#2: The NEC tries to limit the spread of fire and products of combustion in section 300.21. It states, in part, that “openings around electrical penetrations into or through fire-resistant-rated walls, partitions, floors or ceilings shall be fire-stopped using approved methods to maintain the fire resistance rating.” By putting a hole in the fire-rated wall — even though it is hidden and doesn’t go all the way through the wall — it must be firestopped “using approved methods” to return the original fire resistance rating given to that partition.

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