2008 Code Revision and Interpretation Committee Code Interpretation (Last Updated: December 23, 2008)

In an effort to help the electrical industry make a smooth transition into the new Electrical Code and ensure the continuity in the performance of electrical work, the Department of Buildings will be posting code interpretations on its website. Listed below are new code-related questions and corresponding interpretations by the Code Committee. The users of this list should have available the 2005 edition of the NEC and the associated NYC Amendments to the 2005 NEC, as well as (Local Law 49/06) that went into effect on January 1, 2007.

All interpretations are based on the 1999 NEC and associated NY City amendments.

Whenever there are a few sections referenced, the first one is the "lead section", and the rest are secondary sections. All the secondary sections are referenced with the purpose of offering additional clarifications.

Click a topic, or press the enter key on a topic, to reveal its answer.

Chapter 1: General (Section 110.2 to 110.79)

Section 110.26 - (4/9/2008)

  1. We are designing an apartment building with approximately 150 residential units along with commercial space. The electrical service is anticipated to be sized at 4,000A, 120/208V. There will be no cellar within the building. Due to space constraints, the electrical service distribution will be located on the 2nd floor. The Service End Box will be located at grade level within a dedicated room, with one door and no other equipment inside.
    1. Is more than 3 feet clearance required in front of the Service End Box?
      No. At least a 3 foot clearance is required. If he length of the Service End Box is greater than 6 feet, is a 3 feet front clearance required for the entire length of the box?
      Yes. Is the entrance to the room allowed to be through an adjoining Mechanical Room?

Section 110.26(B) - (9/10/2008)

  1. We are considering installing a panelboard in a 2 feet deep niche. The niche is 3 feet and 4 inches wide, 6½ feet high and has a door. When the door is open, the clearance in front of the panelboard would be 10 feet. If we would specify that a sign be mounted on the panelboard reading "Do Not Work on Panelboard With Niche Door Closed", would this installation be acceptable?
    Yes. However, a 2 feet deep niche with a door is considered a closet. Accordingly, as per Section 240.24(D), no storage is permitted inside and a sign stating that shall be posted on the door. Clear spaces shall be maintained in accordance with Section 110.26(B).

Section 110.26(B); 240.24(D) - (9/10/2008)

  1. We are considering installing a panelboard in a location where a door may swing into the working space for the panelboard when opened. If the door will be equipped with locking hardware and a sign reading "Do Not Work on Panelboard Without Locking Door" is posted on it, would this installation be acceptable?
    Yes. Clear spaces shall be maintained in accordance with Section 110.26(B). However, the use of locking hardware is not always practical, as it could restrict egress from the room.

Chapter 2: Wiring and Protection (Code Section 200.1 to 285.25)

Section 210.12 - (12/3/2008)

  1. We are in the process of upgrading the electrical system in a senior citizen facility. The facility has 128 patient rooms that are not provided with permanent provisions for cooking, a physical therapy room, a kitchen, a meeting area and office space. The facility does not have any operating or medical procedure rooms. Is Arc-Fault Circuit-Interrupter protection required for the outlets located in the patient rooms?
    No. See Section 210.12.

Section 210.5(C) - (11/5/2008)

  1. A hospital operating room with an isolated power system was rewired using color coded wires: brown, orange and yellow (boy). The existing 277V lighting system is already using the same color coded wires. Is this a violation of Section 210.5(C) and if so, what should the remedy be?
    Yes, it is a violation. Special permission for the use of an additional identification method to further distinguish these systems must be obtained through the Electrical Advisory Board.

Section 210.52(E)(1) - (6/4/2008)

  1. The NYC amendment to Section 210.52, subsection 210.52(E)(1), requires that at least one receptacle be installed on balconies that are accessible from inside the dwelling units. Is this requirement applicable to all balconies in multi-family high-rise buildings or is it applicable only to the units located at grade level?
    The requirement is applicable to all accessible balconies, not just those located at grade level.

Section 210.63 & 110.2 - (1/9/2008)

  1. We are the electrical contractor for a commercial rehab project, where HVAC equipment is added on the roof. The engineering drawings do not show a GFCI protected receptacle for servicing the equipment. Is such receptacle required to be provided?
    Yes. See Section 210.63. An existing 460V, 5000A service has 4 service switches, one of which is rated 400A. We are re-routing the existing feeder originating at the load side of this switch, keeping the fusing the same. Does such a modification require Advisory Board approval?
    No, if the feeder and the second level protection device remain unchanged. See Section 110.2. Isthe use of nonmetallic boxes for telephone and CATV wiring in hi-rise residential buildings permissible? The cabling would not be enclosed in conduit.
    It is not prohibited under the NYC Electrical Code. In order to energize a new 460V service, does Con Edison require a DOB certificate of inspection, or are the electrical application and the Advisory Board approval letter enough?
    The question should be posed to Con Edison as it is not within the Committee's authority to respond. When installing HVAC and lighting controls, does the communication portion of this cabling need to be installed in conduit?
    This question was tabled as it requires further clarification.

Section 215.2(A)(1) - (11/5/2008)

  1. We are installing an electrical service which originates at the service entrance box (SEB) and includes a service switchboard, a 208/480V step-up transformer (XFMR) and a distribution panel (DP). For the voltage drop calculation, which portion of the circuit should be considered:
    1. From he SEB to the DP, or From the XFMR to the DP?
    In light of the information provided as part of the question, the circuit from the service entrance box to the last overcurrent protection device must be considered for the voltage drop calculation.

Section 220.5(A) - (11/5/2008)

  1. Section 220.5 specifies the nominal voltage levels to be used for calculating branch-circuit and feeder loads. When the incoming service voltage is 265/460V, is it acceptable to use the 277/480V nominal system voltage for performing load calculations?
    No, the incoming service voltage must be used. Section 220.5(A) states that nominal system voltages may be used "unless other voltages are specified".

Section 225.10; 410.37 - (7/9/2008)

  1. Is it permissible to use PVC lighting fixtures and PVC conduit as a measure of preventing corrosion in a pre-cast open garage?
    PVC lighting fixtures may be used for this application as long as they comply with the requirements of Section 410.37. However, the use of rigid nonmetallic conduit is not permitted; see NYC Amendment to section 225.10. Special permission may be requested from the NYC Advisory Board.

Section 240.21 - (12/3/2008)

  1. At a campus type electrical distribution system, the service to one of the buildings is provided from the customer owned substation via an exterior pad-mounted step-down transformer. Are the conductors to the first disconnecting means inside the building considered service conductors? If not, what is the applicable sizing criteria?
    For the described electrical system, the conductors to the first disconnecting means are considered as feeder conductors. These conductors must be sized in accordance with the requirements of Section 240.21.

Section 250.30(A)(7) - (6/4/2008)

  1. Is it acceptable for the neutral of an emergency generator, having a 4-pole transfer switch, to be grounded to the building's structural steel on the roof in lieu of a connection to the water main line in the basement?
    Yes, assuming that the building steel is continuous and connected to the water main line. See Section 250.30(A)(7). If not, is it acceptable to connect to the cold water piping in the proximity of the generator in addition to the connection to structural steel.
    No response required.

Section 250.52(A)(1) - (1/9/2008)

  1. Referencing Section 250.52(A)(1), is it permissible to use an interior water pipe as the ground electrode, when it is located more than 5 feet from the point of service entrance into the building?No. The water pipe shall not be used as a grounding electrode if the connection is more than 5 feet of the water service entrance. Section 250.52(A)(1). Also, see Section 250.104(A) for bonding requirements.

Section 250.52(A)(5) and 250.30(A)(7) - (3/5/2008)

  1. In a building that does not contain steel and where the metal water main is 500 feet away, is it permissible to ground a step-down transformer via a driven rod, below the cellar slab?
    No. A driven rod as described in section 250.52(A)(5) can only be used when the electrodes identified in section 250.30(A)(7) are not available.

Section 250.53(D)(2) - (4/9/2008)

  1. NY City amendment to Section 250.52(A)(1) deleted the NEC Exception, thus prohibiting any grounding electrode connection beyond the first five feet of the main water pipe in industrial and commercial buildings.
    1. Does Does the Exception to Section 250.53(D)(2) apply only to the first 5 feet of the water piping system?
      No. If not, should the Exception to Section 250.53(D)(2) be also deleted?
      This issue will be revisited during the next Electrical Code revision cycle.

Section 250.66 - (4/9/2008)

  1. In a building with a 1600A service, the size of the grounding electrode conductor connected to the water main is 3/0 Copper.
    1. When When jumping out the water meter, should the bonding conductor be the same size as the grounding electrode conductor?
      See Section 250.66. Does Does the Code address the sizing of the jumper across the water meter?
      See Sections 250.66 and 250.53(D)(1).

Chapter 3: Wiring Methods and Materials (Code Section 300.1 to 398-104)

Section 300.1(B) - (5/7/2008)

  1. We are designing a new high-rise residential building. A 1600Amp cable and conduit riser will be feeding meter centers located on floors 6, 8 and 12. The meter centers are listed and range in size from 16 to 33 meters. The upstream overcurrent protection is a 1600Amp fuse. In order to connect each meter center we are proposing to tap the 1600Amp riser with two sets of 4X500 KCMIL (sized for the load) which will terminate at the meter center phase blocks. The feeder tap, less than 10 feet long, will not terminate in an overcurrent protective device. Does the proposed installation comply with the requirements of Section 240.21(B)(1)?
    Yes, if the meter centers comply with the requirements of Section 300.1(B).

Section 310.8 & 358.12(7) - (4/9/2008)

  1. Is it permissible to run low voltage communication cables in electrical metallic tubing (EMT) on the exterior walls of a building?
    No. See Section 310.8 and NYC amendment to Section 358.12(7).

Section 314.29 - (8/6/2008)

  1. We are installing a Building Integrated Photovoltaic (PV) system, where the PV panels are glazed into the exterior curtain wall. The junction boxes are mounted on the back of the PV panels and will be accessed from the exterior of the building using a swing stage scaffold. Considering Considering that Section 314.29 requires that the junction boxes be accessible without removing any part of the building, is it acceptable to access the boxes from the exterior of the building?
    Yes, provided that the flexible connections are of adequate length.

Section 348.60 - (6/4/2008)

  1. In order to connect a 100A panel, a contractor plans to install a 2 inch Flexible Metal Conduit (FMC) inside a hung ceiling over a corridor. The length of the conduit will exceed 200 feet. It is not clear if the code has any length restrictions when using FMC. Would this installation be code compliant?
    Yes, so long as the FMC is installed in accordance with all the requirements of Article 348, including the use of an insulated equipment grounding conductor pursuant to Section 348.60.

Section 368.119(D) & (E) - (1/9/2008)

  1. Section 368.119(D) & (E) requires that a service busway shall be fabricated of aluminum and may have ventilation openings in the sides and bottom of the enclosure.
    1. Can the enclosure be made out of galvanized steel in lieu of aluminum?
      No. What is the reason for requiring an aluminum enclosure?
      Potential for induction heating.

Chapter 4: Equipment for General Use (Code Section 400.1 to 490.74)

Section 400.8 & 590.5(B)(2) - (2/6/2008)

  1. At an interior renovation construction project 'walkie-talkie' radios are stored at night in a locked steel gang box. In order to allow the radios to charge overnight, a heavy duty UL listed, grounded 3 wire, extension cord passes through a 1" hole in the side of the gang box. The hole is filed smooth. The extension cord is supplied by the code compliant temporary power system on the floor. The circuits are protected in accordance with Article 240. The extension cord is inspected daily for wear and tested weekly in accordance with Article 590.6(B)(2). Is this scenario code compliant?
    Yes. See sections 400.8 and 590.6(B)(2).

Section 400.8(1) - (4/9/2008)

  1. We are designing an outdoor tree lighting system that will use 120V lighting fixtures. Is it permissible to use a type SO flexible cord to connect the lighting fixtures to the weatherproof splice box? The cord will likely be laid exposed on the ground.
    No. The use of flexible cords is not a permitted wiring method for permanent installations. See Section 400.8(1).

Section 410.8(B) - (5/7/2008)

  1. Is a 24V LED lighting system, meeting the requirements of Article 411, permitted to be installed under shelves in a clothes closet?
    No. See Section 410.8(B). Are the requirements of Article 410 applicable to lighting systems meeting all the requirements of Article 411?
    The requirements of Article 410 are applicable to luminaires, while the requirements of Article 411 are applicable to the wiring system.

Section 430.102 & Article 695 - (1/9/2008)

  1. It is our understanding that the jockey pump portion of a fire pump may be fed from a non-emergency electrical power source, since this pump is not in use when the fire pump is running. Is our interpretation correct?
    Yes. See Article 695. 2A 120V power feed to a Class E system originates in 30A FCO, fused at 20A, and is tapped within 10 feet of the line side of an existing 208/120V, 5000A service which has 2 x 2000A switches. The neutral on the line side of the FCO is bonded to the FCO housing with a #8 AWG wire. On the load side, the neutral and the hot conductors are of the size # 8 AWG for voltage drop reasons. The load wires leave the FCO and terminate at a dedicated ATS located outside the service room. In the same conduit with the load wires is a #10 AWG ground bar with two #10 AWG ground wires connected to the water main and to the fire command station.
    1. Is Is this grounding installation code compliant? Does the addition of the FCO to the existing service require Advisory Board approval?
    This question was tabled as it requires additional clarification. The design drawings for an HVAC system show a toggle switch adjacent to each smoke damper. Each damper motor draws about 0.89 A at 120 V, and each 20 A circuit supplies up to 5 motors. Considering that the accidental opening of these switches could interfere with the purge process:
    1. Are these switches required by code?If not, are they prohibited by code?
    The disconnect switches are required. See Section 430.102.

Section 430.109(B) - (5/7/2008)

  1. We are requesting further clarification to a January 9, 2008 Committee interpretation relating to disconnect switches for HVAC systems. In response to a question regarding fire dampers, the Committee's answer indicated that disconnect switches are required for 120V dampers that draw less than 1Amp, and Section 430.102 was referenced.
    1. Smoke dampers and associated electric actuators or motors are listed and supplied as a complete assembly, therefore they could be classified as an appliance. If correct, can a branch circuit overcurrent device serve as the disconnecting means, as per Section 422.31(A)?Similarly, other mechanical equipment containing a motor, i.e. a variable-air-volume boxes (VAV) or fan-powered boxes, that are listed and supplied as a unit may also meet the definition of an appliance. If so, may the branch circuit overcurrent device serve as the disconnecting means?
    Section 422.31(A) does not apply. However, Section 430.109(B) allows the use of an overcurrent device to serve as the disconnecting means for stationary motors of 1/8 HP or less.

Chapter 5: Special Occupancies (Code Section 500.1 to 590.7)

Section 517.30(C)(3)(3) - (1/9/2008)

  1. In accordance with Sections 517.13(A) and 517.13(B), is it permissible to use AC type cable for emergency branch circuits in hospitals?
    The use of AC type cable for emergency branch circuits is permissible when the conditions defined in Section 517.30(C)(3)(3) exist.

Section 517.160(A)(4) - (6/4/2008)

  1. In a hospital, the operating rooms were originally provided with two 120Volt, 30Amp isolation panels. We recently determined that these panels can-not support any additional loads.
    1. Can additional branch circuits be brought into these rooms from a local emergency distribution board located outside the operating room inner corridor that has the same ground potential? Can the additional branch circuits originate in a panel board that has a different ground potential?
    No. See Section 517.160(A)(4).

Section 518.4 - (5/7/2008)

  1. The 2008 NEC has introduced a change to Section 518.4 allowing the use of Type AC cable, which contains no insulated equipment grounding conductor, in Assembly Occupancies. Is it permissible to install Type AC cable, with no insulated equipment grounding conductor, in Assembly Occupancies under the current NYC Electrical Code?
    Special permission from the Electrical Advisory Board is required.

Chapter 6: Special Equipment (Code Section 600.1 to 695.14)

Section 620.51 - (7/9/2008)

  1. When installing a listed externally operable motor circuit switch in a locked elevator machine room:
    1. Can a listed, fused, externally operable disconnect switch that is rated for the elevator controller be used as the means of disconnect?
      Yes. Does the word "open" in Section 620.51(A) denote the door of the switch being opened?
      No. Does the word "lockable" in the same Section denote the handle of the switch being mechanically locked as a result of the door being "open?"
      No. If the licensed electrician were to add a clip or component to the listed switch to prevent the handle from moving when the door was open, would the listing of that switch be void?
      Yes, the listing would be voided, unless the clip is listed for the purpose contemplated. Do the words "open" and "lockable" respectively mean electrically disconnected and able to accept a lock per lock-out/tag-out requirement?
      Yes. Does NYC RS-18, ANSI/ASME A17.1-2000 change any of the requirements as stated in Section 620.51 for the required switch?
      Refer to the documents you attached as part of your inquiry. Do the requirements of Section 110.2 change any of the requirements as stated in Section 620.51 for the required switch?
      No. Both sets of requirements are applicable.

Section 695.4(B)(3)(c) - (5/7/2008)

  1. A new laboratory wing that is being built for a university will be supplied with both "normal" and "emergency" power from the campus electrical distribution system. In the proposed desing, the "normal" service consists of two separate 5KV feeders connected to a double-ended substation with a tie-breaker in the middle. The two feeders connec t at each end via separate step-down transformers and main circuit breakers.? In order to connect the Fire Pump, should the bus tap be located before one of the two main circuit breakers or after?
    In order to comply with Code requirements, the tap for the Fire Pump must be made ahead of the main circuit breaker (between the transformer secondary and the circuit breaker), in a transition section of the switchgear assembly. See NYC Amendment 695.4(B)(3)(c). Download the images.

Section 695.6(B) & 695.14(F) - (12/3/2008)

  1. Section 695.6(B) requires that the fire pump supply conductors (normal and emergency) be kept entirely independent of all other wiring, and must be protected to resist fire, structural failure or operational damage. At the same time, Section 695.14(F) requires that the generator control conductors installed between the fire pump transfer switch and the generator be kept entirely independent of other wiring, and must also be protected to resist fire, structural failure or operational damage.
    1. Is it permissible to install class 1 generator control conductors and fire pump supply conductors in the same raceway?
      No. Is it permissible to install the supply conductors for two fire pumps, on either the normal or the emergency circuits, in the same raceway?
      No. Is it permissible to install 2-hour fire rated conductors in parallel in the same raceway?
      No, unless specifically listed for this application. When installing 2-hour fire rated conductors, must all the fire pump branch circuits (normal or emergency) and the generator control circuits be installed in separate raceways, pull or splice boxes containing barriers between circuits?
      Yes. Pull and splice boxes with barriers must maintain the appropriate fire rating. When installing non fire rated conductors, must all the fire pump branch circuits (normal or emergency) and the generator control circuits be installed in separate raceways, pull or splice boxes (containing barriers between all circuits)?
      Yes. Pull and splice boxes with barriers must maintain the appropriate fire rating.

Section 680.23(A)(2) - (1/9/2008)

  1. For one of our fountain projects in NYC, we are considering using an underwater lighting fixture that contains a 120 V/12 V transformer. The transformer is an integral part of the fixture, epoxyed to the fixture housing, supplying 12 V to the fixture lamp. Is such a fixture acceptable?
    No. See Section 680.23(A)(2).

Chapter 7: Special Conditions (Code Section 700.1 to 780.7)

700.5(B) - (8/6/2008)

  1. A "voluntarily installed emergency generator" will be installed in an existing hi-rise residential building. The building's 8 elevators, which are not grouped in an elevator bank, will be connected to the generator. Each elevator serves all floors and is operated by an attendant, 24 hours a day, 7 days a week, while the building's management is on site 365 days a year. Is it permissible to use manual transfer switches to energize each elevator?
    As required by the Department's TPPN #1/07, one elevator must be transferred automatically to the voluntary generator. The other elevators can be on manual transfer subject to the requirements of Section 700.5(B).

Section 700.6(G); 695.4(B)(2)(d) - (8/6/2008)

  1. A New York City hospital is planning to install a new 1000Kw emergency generator. The hospital is considering connecting a mobile generator as a backup for the permanent generator. For the hook-up of the generators, we are proposing the use of two non-fused key interlocked switches that feed the emergency generator bus. The emergency switchboard, the fire pump and the fire alarm will be connected to the bus. Is this an acceptable configuration for the emergency power system?
    The proposed design must include the following:
    1. Overcurrent protection at the point of connection for the portable generator. See Section 700.6(G); The connections for the fire pump and for the fire alarm must be made ahead of the generator disconnect. See Section 695.4(B)(2)(d); and The detail design must be submitted to the Advisory Board for approval.

Section 700.9(B)(4) & 517.43(B) - (12/3/2008)

  1. Section 517.43(B) requires that in a health care facility the patient rooms be provided with heating during emergency operation. In a nursing home, in order to comply with this requirement, we are planning to install dual mode cooling/heating units. In the cooling mode, the unit's compressor operates on 265V normal power, while in the heating mode the unit's fan operates on 265V emergency power. The unit comes with a UL listed dual-connection extension whip. Is it acceptable to connect the normal power wires, the emergency power wires and the extension whip to a common junction box?
    Yes. See section 700.9(B)(4).

Section 700.9(D) - (2/6/2008)

  1. For a new building that is fully sprinklered, is it permissible to run Emergency System Feeders (not including Fire Pump wiring) in the following wiring methods:
    For the premises meeting the criteria for the occupancy types defined in section 700.9 (D) the following answers apply:
      1. Rigid Galvanized conduit, running exposed with THHN insulated conductors?

      1. Rigid Galvanized conduit, running concealed in a hung ceiling space with THHN insulated conductors?

      1. EMT conduit, running exposed with THHN insulated conductors?

    1. EMT conduit, running concealed in a hung ceiling space with THHN insulated conductors?

Section 700.12(C) - (12/3/2008)

  1. Is it permissible per Section 700.12(C) to use a UPS system as the emergency power source for an existing fire alarm system? The UPS system would be connected to the fire alarm system via a dedicated automatic transfer switch.
    Yes, subject to compliance with the NYC Construction Codes, the approval of the Fire Department and other agencies having jurisdiction.

Articles: A subdivision of a Chapter, comprised of a certain number of Sections

Article 210 - (11/5/2008)

  1. In an apartment kitchen, is it permissible to connect a 5Amp, 120V range hood to a microwave branch circuit, a dishwasher branch circuit or to a countertop receptacle branch circuit?
    No. Please see Article 210. In an apartment kitchen, is it permissible to connect two appliances to the same circuit, rated 20Amp, 120V? Each appliance draws no more than 10Amp and could be a refrigerator, a microwave or a dishwasher.
    No. Please see Article 210.

Article 645 - (7/9/2008)

  1. Are multi-outlet assemblies listed for use in Information Technology Equipment rooms (regulated under Article 645) acceptable as a permanent wiring method in areas that may not fully comply with the requirements of Article 645?
    Hard wired multi-outlet assemblies may only be used as permanent wiring in accordance with the listing(s) of the device. Plug-in multi-outlet assemblies may not be used as a permanent wiring method, except as permitted in Article 645 environments.

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