NEC Questions

By Mike Holt for EC&M Magazine

Q1. I am adding a recessed luminaire (listed for a wet location) over a new shower. Does the NEC require this fixture to be GFCI protected?

A1. No, but luminaires above an indoor spa or hot tub must be GFCI protected under most conditions. See 680.43(B)(1) for details.

Q2. I have a customer that has a 4,000A main with six breakers and they want to add a bank of capacitors to correct the power factor. It will require an additional 2,000A disconnect. Is this permitted?

A2. No, 230.71(A) specifies that the service disconnecting means for each service shall consist of not more than six switches or sets of circuit breakers, or a combination of not more than six switches and sets of circuit breakers, mounted in a single enclosure, in a group of separate enclosures, or in or on a switchboard.

Q3. I have a small room in a building that has a data rack with patch panels, a couple of switches and two computers. The inspector is requiring a disconnect switch per 645.10 for the five receptacles in this room. I contend that due to 645.2, this is an optional requirement to be determined by the owner and designer, not a requirement to be enforced by the inspector. What do you think?

A3. According to the NEC Handbook, the requirements in Article 645 are based on the assumption that the room complies with the special construction and fire protection provisions of NFPA 75, Standard for the Protection of Electronic Computer/Data- Processing Equipment.

An information technology equipment room is an enclosed area, with one or more means of entry, that contains computer-based business and industrial equipment. Small terminals, such as remote telephone terminal units, remote data terminals, personal computers, and cash registers in stores and supermarkets, are not covered by Article 645.

Q4. I remember being taught not to use a panel or disconnect as a raceway, but I cannot find it in the Code book. I want to be able to justify the extra cost other than just knowing it is the right thing to do. Could you point me in the right direction?

A4. Cabinets (contains panelboards), cutout boxes (enclosures for switches), and meter socket enclosures can be used as a raceway for conductors feeding through if the conductors do not fill the wiring space at any cross section to more than 40 percent. Figure 312-5

In addition, splices and taps are permitted if the splice or tap does not fill the wiring space at any cross section to more than 75 percent. Figure 312-6

Q5. I'm stumped. When we use MC cable, it has been our standard practice to terminate the cable with an "anti-short" bushing. I've noticed several electricians using connectors without an anti-short bushing. Doesn’t the NEC require anti-short bushings for MC cable?

A5. No, anti-short bushings are not required for MC cable (metal-clad cable). However, 320.40 specifies that an insulating bushing or its equivalent protection shall be provided between the conductors and the armor of Type AC cable (armored cable).

Q6. What is the maximum number of receptacles and luminaires permitted on a 15A circuit in a dwelling unit?

A6. There is no NEC rule limiting the maximum number of receptacles and luminaires on a dwelling unit general-purpose circuit.

Q7. We have a new safety rep that says we cannot use our existing extension cords because they are underrated. The extension cords we use are 16 AWG. He claims they have to be 12 AWG because they are on a 20A breaker.

A7. According to 240.5(B)(3), a 16 AWG flexible cord used in listed extension cord sets shall be permitted to be supplied by a 20A or less branch circuit.

Q8. Is there specific color-coding assigned to different voltages in the NEC?

A8. The NEC does not require color-coding of ungrounded conductors, except for the high-leg conductor when a grounded (neutral) conductor is present [110.15, 215.8 and 230.56]. However, electricians often use the following color system for power and lighting conductor identification:

  • 120/240V, 1; black, red, white
  • 120/240V, 3; black, orange, blue, white
  • 208Y/120V, 3; black, red, blue, white
  • 480Y/277V, 3; brown, purple, yellow, gray

Q9. Recently, I have come across a situation where an electrical contractor has renovated a residential bathroom and has located a switch within three inches horizontally of the outer edge of the bathtub rim, 54 inches above the floor. The user can easily reach these switches while standing in the tub, dripping wet. Doesn’t this violate the NEC?

A9. No, this installation does not violate the NEC. According to 404.4, switches shall not be installed “within wet locations in tub or shower spaces” unless installed as part of a listed tub or shower assembly. In addition, GFCI is not required for the switch.

Q10. We are constructing office space and are trying to determine the allowance for the number of general-purpose receptacle outlets required by the NEC for each office. Could you tell me the requirements?

A10. The NEC does not contain any requirements on the number of general-purpose receptacle outlets in commercial or industrial facilities. This is a design issue.

Q11. Where in the 2002 Code book can I find the locations required for smoke detectors?

A11. The location requirement for smoke detectors is contained in the NPFA 72 National Fire Alarm Code, not in the NFPA 70 National Electrical Code.

Mike Holt’s Comment: Please let me know your feedback.

 

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