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I want to run 1" LV conduit (Carlon Resi-gard) through the attic. Basically, I am using the attic for the "horizontal" run from one room to another.

I will be sealing the hole with some caulking, but what else do I need to know?

  • Is it safe to just drill into the attic from the room below?
  • Does the conduit have to run above the insulation (stapled to something), or can it just lay on the floor of the attic?
  • I think it would be best to break the conduit with at least one "pull box" in the attic. Would that box need to be a closed gang box with a blank plate? Or can it be like any other LV backless gang box?
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  1. It is okay to drill from below as long as you know, for a fact that you are not going to hit ANYTHING, otherwise go into the attic.
  2. The conduit can run on the floor of the attic but I would use a two hole strap and get it above the insulation .
  3. I would use a plastic pull box with a plastic cover, the backless may not give you the support that you need when pulling your wires.
  4. As for the holes that you make, I would use a fire foam to seal.

Update to the post and for your reading pleasure. This is for Carlon

The following is from here. It was going to be hard to copy it on my scanner so I copied and pasted the BEST part.

Approved Uses: Typical Applications:

  • Concrete slab – NEC Article 362
  • Walls - wood stud, masonry and metal stud – NEC Article 362.
  • Ceilings - permanent or dropped (free air only) – NEC Article 362.
  • Exposed – NEC Article 362
  • Public Assembly – NEC Section 518.4, in nonfire rated and certain five rated structures
  • Prewired – NEC Article 362
  • Classified by UL 1479 for Through Penetration Firestop Systems in UL Guide Category XHEZ and current UL Fire Resistance Directory
  • Three hour rated floor/ceiling assemble
  • Raised Floors – NEC Section 645.5(D)(2)
  • Exposed or concealed in building above three floors when a fire sprinkler system is installed in accordance with NFPA 13–NEC Section 362.10(2)

    For use in residential attics up to 3 feet above the bottom of the ceiling joist.

Update to the Update. Before anyone says anything I realize I made a mistake and I am falling on my own sword. The above is for Carlon Flex-Plus Blue not Carlon Resi-gard (Think it is time to go back to the eye doctor) so here is what I did find.(I was sure the OP said flex plus)

The PDF did said attic but going in to not through but it did also said that "Resi-Gard is rated as a general-purpose raceway per National Electrical Code (NEC) Article 770, for Optical Fiber Cables and Raceways and Article 800 for Communications Circuits".

So with that, I would use Resi-Gard in the walls and Flex-Plus Blue for your raceway in the attic.

  • That last PDF was a great source of info. I couldn't find any dates on it though, do you know how current those products are? – Slav Aug 18 '15 at 14:04
  • That is straight from Carlon, so to me it should be the latest. – WarLoki Aug 18 '15 at 14:13
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NEC Article 362

I've copied the NEC portions that cover corrugated HDPE (High Density Polyethylene) conduit for your reading pleasure. The NEC differentiates between corrugated and non corrugated HDPE conduits by referring to corrugated HDPE as ENT and non corrugated as just HDPE. Non corrugated HDPE is not allowed at all in any buildings, whereas corrugated is.

Also, the NEC doesn't specifically differentiate orange corrugated HDPE from blue corrugated HDPE but instead simply refers to Optical Fiber Cable conduit as "Innerduct".

770.12 Innerduct for Optical Fiber Cables.

Listed plenum communications raceway, listed riser communications raceway, and listed general-purpose communications raceway selected in accordance with the provisions of Table 800.154(b) shall be permitted to be installed as innerduct in any type of listed raceway permitted in Chapter 3.

Also interesting is Carlon, the maker of Riser-gard refers to "Innerduct" when comparing their different Riser-gard products. See here. I think it is safe, in general, to compare innerduct to the safety regulations required for ENT installations.

The most important parts for you will be 362.12 Uses Not Permitted, 362.30 Securing and Supporting A-B, and 362.26 Bends.

Notably Securing and Supporting(B) addresses your horizontal attic runs which permits the rafters to support the ENT if they are not greater than 3' apart and provided you secure the ENT within 3' of every pull/junction box.

Also interesting is 362.10 which only permits buildings not exceeding three floors for exposed work.

And anything over 122°F ambient temperature is not permitted unless listed otherwise. This may be a problem for hot summer attics without proper ventilation.

As for drilling into attics that is more a building code issue. This answer addresses the codes for that.

II. Installation 362.10 Uses 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:

a. For exposed work, where not prohibited by 362.12

b. 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 identified in listings of fire-rated assemblies. The 15-minute-finish-rated thermal barrier shall be permitted to be used for combustible or noncombustible walls, floors, and ceilings.

Exception to (2): Where a fire sprinkler system(s) is in stalled in accordance with NFPA 13-2013, Standard for the Installation of Sprinkler Systems, on all floors, ENT shall be permitted to be used within walls, floors, and ceilings, exposed or concealed, in buildings exceeding three floors above grade. Informational Note: A finish rating is established for 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 16.3°C (325°F) as measured on the plane of the wood nearest the fire. A finish rating is not in tended 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 suspended 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 ap proved 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 temperature 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 permitted 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) Where the voltage is over 600 volts

(6) In exposed locations, except as permitted by 362.10(1), 362.10(5), and 362.10(7)

(7) In theaters and similar locations, except as provided in 518.4 and 520.5

(8) Where exposed to the direct rays of the sun, unless identified as sunlight resistant

(9) Where subject to physical damage

362.20 Size.

(A) Minimum. ENT smaller than metric designator 16 (trade size 1/2") shall not be used.

(B) Maximum. ENT larger than metric designator 53 (trade size 2) shall not be used. Informational Note: See 300.1

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 and supported in accordance with 362.30(A) and (B).

(A) 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.

Exception No. 1: Lengths not exceeding a distance of 1.8 m (6 ft) from a luminaire terminal connection for tap connections to lighting luminarie 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 accessible ceiling to luminaire(s) or other equipment.

Exception No. 3: For concealed work in finished buildings or prefinished wall panels where such securing is impracticable, unbroken lengths (without coupling) of ENT shall be permitted to be fished.

(B) 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 enclosure design provides equivalent protection.

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. III. Construction Specifications

362.100 Construction. ENT shall be made of material that does not exceed the ignitibility, flammability, smoke gen eration, and toxicity characteristics of rigid (nonplasticized) polyvinyl chloride. ENT, as a prewired manufactured assembly, shall be provided in continuous lengths capable of being shipped in a coil, reel, or carton without damage.

362.120 Marking. (This is usually done by the manufacturer)

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 printed 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 3.10.120. (This is usually done by the manufacturer)

  • Tons of useful information. Wish I could accept more than 1 answer. The other answer touched up on more of my points however. Thank you for your time however. – Slav Aug 19 '15 at 14:22

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