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Article 362

Electrical Nonmetallic Tubing: Type ENT

Part I. General

  1. Scope. This article covers the use, installation, and construction specifications for electrical nonmetallic tubing (ENT) and associated fittings.
  2. Definition.

Electrical Nonmetallic Tubing (ENT). A nonmetallic, pliable, corrugated raceway of circular cross section with integral or associated couplings, connectors, and fittings for the installa‐ tion of electrical conductors. ENT is composed of a material that is resistant to moisture and chemical atmospheres and is flame retardant.

A pliable raceway is a raceway that can be bent by hand with a reasonable force but without other assistance.

362.6 Listing Requirements. ENT and associated fittings shall be listed.

Part II. Installation

362.10 Uses Permitted. For the purpose of this article, the first floor of a building shall be that floor that has 50 percent or more of the exterior wall surface area level with or above finished grade. One additional level that is the first level and not designed for human habitation and used only for vehicle parking, storage, or similar use shall be permitted. The use of ENT and fittings shall be permitted in the following:

  1. In any building not exceeding three floors above grade as follows:
    1. For exposed work, where not prohibited by 362.12
    2. Concealed within walls, floors, and ceilings
  2. In any building exceeding three floors above grade, ENT shall be concealed within walls, floors, and ceilings where the walls, floors, and ceilings provide a thermal barrier of material that has at least a 15-minute finish rating as iden‐assemblies containing combustible (wood) supports. The finish rating is defined as the time at which the wood stud or wood joist reaches an average temperature rise of 121°C (250°F) or an individual temperature of 163°C (325°F) as measured on the plane of the wood nearest the fire. A finish rating is not intended to represent a rating for a membrane ceiling.
  3. In locations subject to severe corrosive influences as covered in 300.6 and where subject to chemicals for which the materials are specifically approved.
  4. In concealed, dry, and damp locations not prohibited by 362.12.
  5. Above suspended ceilings where the suspended ceilings provide a thermal barrier of material that has at least a 15-minute finish rating as identified in listings of fire- rated assemblies, except as permitted in 362.10(1)a.Exception to (5): ENT shall be permitted to be used above suspen‐ ded ceilings in buildings exceeding three floors above grade where the building is protected throughout by a fire sprinkler system installed in accordance with NFPA 13-2013, Standard for the Installation of Sprinkler Systems.
  6. Encased in poured concrete, or embedded in a concrete slab on grade where ENT is placed on sand or approved screenings, provided fittings identified for this purpose are used for connections.
  7. For wet locations indoors as permitted in this section or in a concrete slab on or belowgrade, with fittings listed for the purpose.
  8. Metric designator 16 through 27 (trade size 1∕2 through 1) as listed manufactured prewired assembly.Informational Note: Extreme cold may cause some types of nonmetallic conduits to become brittle and therefore more susceptible to damage from physical contact.
  9. Conductors or cables rated at a temperature higher than the listed temperature rating of ENT shall be permitted to be installed in ENT, if the conductors or cables are not operated at a temperature higher than the listed temper‐ ature rating of the ENT.

362.12 Uses Not Permitted. ENT shall not be used in the following:

  1. In any hazardous (classified) location, except as permit‐ ted by other articles in this Code
  2. For the support of luminaires and other equipment
  3. Where subject to ambient temperatures in excess of 50°C (122°F) unless listed otherwise
  4. For direct earth burial
  5. In exposed locations, except as permitted by 362.10(1), 362.10(5), and 362.10(7)
  6. In theaters and similar locations, except as provided in518.4 and 520.5ARTICLE 366 — AUXILIARY GUTTERS 366.2
  7. Where exposed to the direct rays of the sun, unless identi‐ fied as sunlight resistant
  8. Where subject to physical damage

362.20 Size.

  1. Minimum. ENT smaller than metric designator 16 (trade size 1∕2) shall not be used.
  2. Maximum. ENT larger than metric designator 63 (trade size 21∕2) shall not be used.

Informational Note: See 300.1(C) for the metric designators and trade sizes. These are for identification purposes only and do not relate to actual dimensions.

362.22 Number of Conductors. The number of conductors shall not exceed that permitted by the percentage fill in Table 1, Chapter 9.

Cables shall be permitted to be installed where such use is not prohibited by the respective cable articles. The number of cables shall not exceed the allowable percentage fill specified in Table 1, Chapter 9.

362.24 Bends — How Made. Bends shall be so made that the tubing will not be damaged and the internal diameter of the tubing will not be effectively reduced. Bends shall be permitted to be made manually without auxiliary equipment, and the radius of the curve to the centerline of such bends shall not be less than shown in Table 2, Chapter 9 using the column “Other Bends.”

362.26 Bends — Number in One Run. There shall not be more than the equivalent of four quarter bends (360 degrees total) between pull points, for example, conduit bodies and boxes.

362.28 Trimming. All cut ends shall be trimmed inside and outside to remove rough edges.

362.30 Securing and Supporting. ENT shall be installed as a complete system in accordance with 300.18 and shall be securely fastened in place by an approved means and suppor‐ ted in accordance with 362.30(A) and (B).

  1. Securely Fastened. ENT shall be securely fastened at intervals not exceeding 900 mm (3 ft). In addition, ENT shall be securely fastened in place within 900 mm (3 ft) of each outlet box, device box, junction box, cabinet, or fitting where it terminates. Where used, cable ties shall be listed as suitable for the application and for securing and supporting.Exception No. 1: Lengths not exceeding a distance of 1.8 m (6 ft) from a luminaire terminal connection for tap connections to lighting lumin‐ aires shall be permitted without being secured.Exception No. 2: Lengths not exceeding 1.8 m (6 ft) from the last point where the raceway is securely fastened for connections within an accessi‐ ble ceiling to luminaire(s) or other equipment.Exception No. 3: For concealed work in finished buildings or prefin‐ ished wall panels where such securing is impracticable, unbroken lengths (without coupling) of ENT shall be permitted to be fished.
  2. Supports. Horizontal runs of ENT supported by openings in framing members at intervals not exceeding 900 mm (3 ft) and securely fastened within 900 mm (3 ft) of termination points shall be permitted.

362.46 Bushings. Where a tubing enters a box, fitting, or other enclosure, a bushing or adapter shall be provided to protect the wire from abrasion unless the box, fitting, or enclo‐ sure design provides equivalent protection.

Informational Note: See 300.4(G) for the protection of conduc‐ tors size 4 AWG or larger.

362.48 Joints. All joints between lengths of tubing and between tubing and couplings, fittings, and boxes shall be by an approved method.

362.56 Splices and Taps. Splices and taps shall be made only in accordance with 300.15.

Informational Note: See Article 314 for rules on the installation and use of boxes and conduit bodies.

362.60 Grounding. Where equipment grounding is required, a separate equipment grounding conductor shall be installed in the raceway in compliance with Article 250, Part VI.

Part III. Construction Specifications

362.100 Construction. ENT shall be made of material that does not exceed the ignitibility, flammability, smoke genera‐ tion, and toxicity characteristics of rigid (nonplasticized) poly‐ vinyl chloride.

ENT, as a prewired manufactured assembly, shall be provi‐ ded in continuous lengths capable of being shipped in a coil, reel, or carton without damage.

362.120 Marking. ENT shall be clearly and durably marked at least every 3 m (10 ft) as required in the first sentence of 110.21(A). The type of material shall also be included in the marking. Marking for limited smoke shall be permitted on the tubing that has limited smoke-producing characteristics.

The type, size, and quantity of conductors used in prewired manufactured assemblies shall be identified by means of a prin‐ ted tag or label attached to each end of the manufactured assembly and either the carton, coil, or reel. The enclosed conductors shall be marked in accordance with 310.120.

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