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CSA C22.2 No. 227.1-19: Electrical Nonmetallic Tubing and Fittings — Technical Requirements and Compliance Guide
An in-depth review of the scope, material specifications, performance testing, and implementation of ENT systems in Canadian electrical installations.
Scope and Application of CSA C22.2 No. 227.1-19
CSA C22.2 No. 227.1-19, titled Electrical Nonmetallic Tubing (ENT) and Fittings, forms part of the Canadian Electrical Code (CE Code) Part II series of standards. This standard specifies the minimum safety and performance requirements for electrical nonmetallic tubing, also known as ENT, and associated fittings intended for use in accordance with the CE Code Part I (CSA C22.1). ENT is a pliable, corrugated tubing made from polyvinyl chloride (PVC) or other suitable thermoplastic materials, designed to provide a raceway for conductors and cables in dry, damp, and wet locations where a low-smoke, flame-retardant system is required.
The standard covers ENT systems for voltages up to 600 V and is primarily for applications in concrete encasement, embedment in masonry, concealed installations in walls and ceilings, and exposed locations protected from physical damage. Key application areas include commercial buildings, industrial facilities, and residential structures where flexibility and ease of installation are advantageous.
Note: CSA C22.2 No. 227.1-19 supersedes the 2006 edition and aligns with new material technologies, updated flame propagation test methods, and harmonization with UL 1653 (the U.S. standard for ENT). Users should ensure they reference the latest edition for certification purposes.
Technical Requirements and Material Specifications
Construction and Dimensions
ENT must be manufactured from a rigid polyvinyl chloride (PVC) or other certified thermoplastic compound that meets specified physical, electrical, and thermal properties. The tubing shall be corrugated to allow bending without the use of special tools, and it must maintain its internal diameter and wall thickness within tolerances that guarantee conductor capacity and mechanical integrity.
Table 1 below summarizes the dimensional requirements for the most common trade sizes of ENT as specified in Clause 6 of the standard.
| Trade Size (Metric) | Internal Diameter Min. (mm) | Wall Thickness Min. (mm) | Bend Radius Min. (mm) |
|---|---|---|---|
| 16 (1/2 in.) | 13.8 | 0.50 | 105 |
| 21 (3/4 in.) | 18.5 | 0.55 | 140 |
| 27 (1 in.) | 24.0 | 0.60 | 175 |
| 35 (1¼ in.) | 31.5 | 0.65 | 210 |
| 41 (1½ in.) | 37.0 | 0.70 | 245 |
| 53 (2 in.) | 49.0 | 0.80 | 315 |
Temperature Rating and Marking
ENT is temperature-rated for continuous use at 90°C for dry locations and 75°C for wet locations, with a maximum short-circuit rating of 150°C (based on conductor ampacity). All products must be durably marked with the trade size, manufacturer identification, the designation “ENT”, and the temperature rating. The standard also requires marking for flame propagation performance, typically indicated as “FT4” or “FT6” when tested in accordance with CSA C22.2 No. 0.17.
Tip: When selecting ENT for concrete encasement, ensure the product is marked as suitable for direct burial or concrete embedment. Some ENT products are restricted to concealed use above ground only. Always verify the manufacturer’s installation instructions.
Performance Testing and Compliance Notes
Flame Propagation and Smoke Generation
One of the most critical safety requirements in CSA C22.2 No. 227.1-19 is the flame propagation test. ENT systems must be tested in accordance with the vertical tray flame test defined in UL 1685 (or CSA C22.2 No. 0.17). The maximum allowable flame spread distance is 1.5 m, and the peak smoke release rate must not exceed 0.25 m²/s. These limits are designed to reduce the contribution of the raceway to fire growth in building cavities. Products meeting FT4 (vertical tray) or FT6 (horizontal/vertical tray) ratings are acceptable; however, the more stringent FT6 rating is preferred for plenum and other air-handling spaces.
Warning: Do not substitute ENT with standard residential “smurf tube” (often used for low-voltage applications) without verifying its FT4/FT6 listing. Only ENT marked to CSA C22.2 No. 227.1-19 is recognized for general building use under the Canadian Electrical Code.
Mechanical Strength and Impact Resistance
ENT must withstand a minimum impact force of 20 J at room temperature when tested in accordance with Clause 7.2 of the standard. This ensures the tubing can resist typical construction site handling and concrete pouring loads. Additionally, compression tests require the tubing to recover at least 85% of its original internal diameter after being compressed to 50% of its original height for 10 minutes. Fittings must also meet pull-out forces that are at least equal to 70% of the tensile strength of the tubing itself.
Compliance Insight: Listing to CSA C22.2 No. 227.1-19 is required by the CE Code for all ENT installations. Products that bear the CSA mark or are certified by an accredited certification body simplify inspection and reduce project risk. Many jurisdictions also require field labeling of exposed ENT runs.
Installation and Support Requirements
The standard references the CE Code Part I for installation spacing and support intervals. Generally, ENT must be secured at intervals not exceeding 0.9 m and within 0.3 m of every outlet box or fitting. For horizontal runs exposed to physical damage, the use of metallic conduit or additional protection is advisable. The standard does not cover concrete-tight or moisture-sealing requirements for fittings; those are covered by the product family standard CSA C22.2 No. 18.
Safety Critical: Never use ENT in hazardous locations (Class I, Division 1 or Zone 0/1) unless the tubing and associated fittings are specifically listed for such environments. ENT is not inherently explosion-proof.
Frequently Asked Questions (FAQs)
Q: What is the difference between CSA C22.2 No. 227.1-19 and the previous 2006 edition?
A: The 2019 edition introduced more stringent flame propagation testing (including smoke measurement), updated mechanical impact requirements (from 15 J to 20 J), and aligned dimensional tolerances with UL 1653 for improved cross-border harmonization. Marking requirements now include a mandatory temperature rating on the product itself.
A: The 2019 edition introduced more stringent flame propagation testing (including smoke measurement), updated mechanical impact requirements (from 15 J to 20 J), and aligned dimensional tolerances with UL 1653 for improved cross-border harmonization. Marking requirements now include a mandatory temperature rating on the product itself.
Q: Can ENT be used in wet locations according to CSA C22.2 No. 227.1-19?
A: Yes, ENT is suitable for wet locations when installed in accordance with the CE Code Part I. The standard requires that tubing intended for wet locations be marked accordingly. However, ENT cannot be used for direct underground burial unless specifically listed for that purpose and protected from mechanical damage. Concrete encasement is permitted as long as the conduit is identified for that application.
A: Yes, ENT is suitable for wet locations when installed in accordance with the CE Code Part I. The standard requires that tubing intended for wet locations be marked accordingly. However, ENT cannot be used for direct underground burial unless specifically listed for that purpose and protected from mechanical damage. Concrete encasement is permitted as long as the conduit is identified for that application.
Q: Are ENT fittings required to be the same brand or standard?
A: Fittings must comply with CSA C22.2 No. 227.1-19 as well, and they must be compatible with the specific ENT product. Many manufacturers design fittings for interlocking with their own ENT corrugation profile. Using mixed brands may invalidate certification and compromise mechanical pull-out strength. Always consult the manufacturer’s compatibility list.
A: Fittings must comply with CSA C22.2 No. 227.1-19 as well, and they must be compatible with the specific ENT product. Many manufacturers design fittings for interlocking with their own ENT corrugation profile. Using mixed brands may invalidate certification and compromise mechanical pull-out strength. Always consult the manufacturer’s compatibility list.
This article is provided for informational purposes only. Always refer to the latest edition of CSA C22.2 No. 227.1-19 and consult with a certified electrical professional for specific application guidance. Updated in 2026.