Article 210—Branch Circuits; Article 240—Overcurrent Protection; Article 334—Nonmetallic-Sheathed Cable: Types NM, NMC and NNS; Article 422—Appliances; Article 440—Air Conditioning and Refrigerating Equipment; Article 647—Sensitive Electronic Equipment; Article 680—Swimming Pools, Fountains and Similar Installations; Article 695—Fire Pumps; Article 700—Emergency Systems.
Branch circuit for fire alarm system:
Q: Is the branch circuit for a fire alarm system permitted to be connected to the emergency system?
A: Yes, if acceptable to the authority having jurisdiction (AHJ). Fine Print Note 3 to 700.1, which is the scope statement for Article 700—Emergency Systems, of the National Electrical Code (NEC) mentions fire detection and alarm systems as equipment that may be supplied by the emergency system. The agency that requires the installation of an emergency system (municipal, state, federal or any governmental agency having jurisdiction) should be consulted before connecting fire alarms to the emergency system to be sure that there is no objection to this arrangement.
Although FPN 3 mentions fire alarms as a load that may be connected to the emergency system, remember that Fine Print Notes are for information only [see 90.5(C)].
Q: Does Part V of Article 680 apply to a cord-and-plug-connected fountain? This fountain will be located in the entrance foyer of a hotel.
A: A fountain is defined in 680.2 as “Fountains, ornamental pools, display pools, and reflection pools. The definition does not include drinking fountains.” There is another definition for permanently installed decorative fountains and reflection pools that reads, “Those that are constructed in the ground, on the ground, or in a building in such a manner that the fountain cannot be readily dissembled for storage, whether or not served by electrical circuits of any nature. These units are primarily constructed for their aesthetic value and are not intended for swimming or wading.”
Part V of Article 680 applies to permanently installed fountains and portable (cord-and-plug-connected) fountains that are larger than 5 feet in any dimension. Because the size of the fountain is not mentioned in the question, it is necessary to provide answers for both a small fountain and one larger than 5 feet.
For fountains larger than 5 feet, all exposed non-current-carrying metal parts must be grounded by an insulated copper equipment-grounding conductor that is part of the supply cord. The fountain and power supply cord must be protected by a ground-fault circuit interrupter (GFCI). There are additional requirements for the type of cord, sealing and terminations in 680.56. All 15- and 20-ampere, 125-volt and 250-volt receptacles within 20 feet of the fountain must have GFCI protection to comply with 680.58.
Small portable fountains must meet the requirements for cord-connected appliances in Article 422. The attachment cap and receptacle may serve as the disconnecting means where accessible and where the pump horsepower does not exceed these values for a single-phase motor: 15 ampere, 125-volt receptacle—1.5 horsepower; 250-volt, single-phase 15-ampere receptacle—1.5 horsepower; 125-volt single phase, 20 ampere receptacle—1 horsepower; and 20 ampere, 250-volt single-phase receptacle—2 horsepower. Other receptacle ratings also have horsepower ratings. These may be found in the “2006 Guide Information for Electrical Equipment—The White Book” published by Underwriters Laboratories Inc.
Where the attachment cap does not serve as a disconnecting means and there is no power switch at the fountain, a disconnecting means must be provided within sight of the fountain or the out of sight disconnect must be capable of being locked in the off position (see 422.33 and 422.31).
AFCI for clothes closet
Q: A bedroom in a dwelling unit has a clothes closet. The wall switch for the closet light is in the bedroom. Is arc-fault protection required to this switch and luminaire (lighting fixture)?
A: The National Electrical Code does not require arc-fault circuit interrupter (AFCI) protection for this wall switch and closet luminaire (lighting fixture). 210.12, Part (B) states, “All 120-volt, single-phase, 15- and 20-ampere branch circuits supplying outlets installed in dwelling unit bedrooms shall be protected by a listed arc-fault circuit interrupter, combination type installed to provide protection of the branch circuit.”
Branch/feeder AFCIs shall be permitted to be used to meet the requirements of 210.12(B) until Jan. 1, 2008.” Notice the use of the word “outlet” in the rule, which is defined in Article 100 as “A point on the wiring system at which current is taken to supply utilization equipment.” Since a wall switch does not meet this definition, AFCI protection is not required. Although the luminaire (lighting fixture) meets the definition of an outlet, it is not in the bedroom; therefore, arc-fault protection is not required.
Voltage drop limits
Q: Are there any requirements in the NEC that limit voltage drop on feeders and branch circuits?
A: There are Fine Print Notes that recommend a maximum voltage drop of 5 percent for feeders and branch circuits. These appear in 210.19 as Fine Print Note No. 4 in 210.19(A)(1) and Fine Print Note No. 2 in 215.2(A)(3).
There is a requirement for voltage drop not to exceed 1.5 percent on branch circuits and not to exceed 2.5 percent total on feeders and branch circuits. The combined voltage drop on feeder and branch-circuit conductors cannot exceed 2 percent for receptacle branch circuits that supply cord-connected equipment. These requirements are in Article 647—Sensitive Electronic Equipment.
There is a mandatory voltage drop requirement for Fire Pumps in Article 695. Voltage drop cannot exceed 15 percent of normal fire pump controller rated voltage under motor-starting conditions and cannot exceed 5 percent of the voltage rating of the motor when the motor is operating at 115 percent of full-load current.
Overcurrent protection for motor branch-circuit conductors
Q: In a previous issue of ELECTRICAL CONTRACTOR magazine, there was a question about the size of the branch circuit overcurrent protective device for 10 AWG copper conductors supplying an air conditioner with a nameplate rating of 24 amperes. Among other things, the nameplate has the following information: Branch-circuit selection current 24 amperes; 240 volts single-phase; maximum overcurrent protection 40 amperes. Some readers questioned the use of 40-ampere overcurrent protection on 10 AWG copper conductors, saying that overcurrent protection for 10 AWG copper conductors is limited to 30 amperes by 240.4(D).
A: These readers are partially correct. Thirty amperes is the maximum overcurrent protection for 10 AWG copper unless modified by Table 240.24(G). This table allows the overcurrent protection to be modified for air conditioning and refrigeration equipment branch-circuit conductors as mentioned in Parts III and VI of Article 440.
The definition for branch-circuit selection current in 440.2 allows this value of current to be used for determining the branch-circuit conductor ampacity and other components of the circuit.
Part III of Article 440 states, “The provisions of Part III specify devices intended to protect the branch-circuit conductors, control apparatus, and motors in circuits supplying hermetic refrigerant motor-compressors against overcurrent due to short circuits and grounds. They are in addition to or amendatory of the provisions of Article 240.”
Branch-circuit conductors for the motor-compressor are allowed to have a minimum ampacity of 125 percent of the branch-circuit selection current to comply with 440.32, and the short-circuit and ground-fault protection is allowed to be 175 percent of the branch-circuit selection current by 440.22(A). The term “short-circuit and ground-fault protection” is used because the branch-circuit overcurrent device does not provide overcurrent protection for the conductors, which is provided by the overload relays in the compressor starter or built-in overload protection in the compressor motor. Although the branch-circuit conductors are not adequately protected from overloading at the point where they receive their supply, they are protected by the thermal overloads built into the compressor.
GFCIs for evaporative coolers?
Q: Why was the requirement for 15- or 20-ampere, 125-volt GFCI receptacle removed for air conditioning equipment located at one- and two-family dwelling units?
A: The exception to 210.63 does not apply to remote sealed hermetic condensing units. It only applies to “swamp” or evaporative coolers, which generally are free-standing wood units on the roofs of dwelling units in the southwestern United States. They usually consist of a water- drip filter or material on all four sides on which water trickles down and a fan. The fan sucks air through this moist material and discharges it into the home. In areas of the United States where the relative humidity is low in the summer, evaporative coolers make a good, economical cooling system. Since an evaporative cooler usually has only a fan motor, the Code Making Panel agreed that a GFCI receptacle was not required for servicing.
Terminating a neutral conductor
Q: Is it a Code violation to divide the neutral conductor strands into two parts and terminate the conductor in two adjacent holes in the neutral bus?
A: Yes, it is. Connections of conductors must ensure a thoroughly good connection. A stranded neutral conductor should not be stripped and divided into parts to fit into small terminals on the neutral bus. Besides not meeting the requirement of 110.3(B), this method of terminating the neutral conductor does not satisfy 408.31, which states, “Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard in an individual terminal that is not also used for another conductor.”
Cable in unfinished basements
Q: Does the National Electrical Code permit nonmetallic sheathed cable to be run diagonally and secured to the underside of joists in an unfinished basement in a one-family dwelling unit?
A: Yes, if the cable contains two or more 6 AWG conductors or three 8 AWG conductors. Otherwise, holes must be bored in the joists for the cable, or it must be secured to running boards. This requirement appears in 334.12(C). EC
FLACH, a regular contributing Code editor, is a former chief electrical inspector for New Orleans. He can be reached at 504.734.1720.