CSA C22.2 No. 128-16: Rainproof, Raintight, and Watertight Enclosures for Electrical Equipment

Scope and Purpose

CSA C22.2 No. 128-16 establishes the minimum construction, performance, and test requirements for enclosures intended to protect electrical equipment from the ingress of water and moisture in outdoor or wet locations. This standard applies to metallic and non-metallic enclosures that rely on gaskets, sealing compounds, or interlocking joints to achieve a defined degree of protection against rain, snow, and splashing water.

As part of the CSA C22.2 series (Canadian Electrical Code, Part II), this standard is referenced by the CE Code Part I (CSA C22.1) for installations where enclosures must resist environmental exposure. It supersedes the 2006 edition and aligns with modern ingress protection (IP) rating methodologies described in IEC 60529 while retaining specific Canadian climate requirements.

Enclosures covered by this standard are classified into three types:

• Rainproof – Prevent the entry of rain and snow under specified test conditions.
• Raintight – Meet a higher level of water protection, verified by a hose-down test.
• Watertight – Withstand submersion in water for defined times and depths.

The scope includes enclosures for junction boxes, disconnect switches, control panels, and other equipment permanently mounted in outdoor environments. Portable enclosures and those used in hazardous locations fall under additional standards (e.g., CSA C22.2 No. 60079 series) and are not within the primary scope of this document.

Technical Requirements

Construction and Material Requirements

CSA C22.2 No. 128-16 mandates that all enclosures be constructed from materials resistant to corrosion and weather aging. Metal enclosures must be either inherently corrosion-resistant (e.g., stainless steel, aluminum) or provided with a protective coating system that passes a 96-hour salt spray test as per ASTM B117. Non-metallic enclosures must be evaluated for ultraviolet (UV) resistance, impact strength at temperatures down to -40 °C, and flammability (UL 94 V-2 or better).

Gaskets used in raintight and watertight enclosures must be mechanically retained or vulcanized to prevent displacement during handling. Openings for conduit or cable entries must be equipped with sealing washers or thread sealants to maintain the enclosure integrity.

Degree of Protection – Equivalent IP Marking

While the standard retains legacy terms (rainproof, raintight, watertight), it also provides a cross-reference table to the IP Code (IEC 60529). This helps specifiers select enclosures when a project requires an IP rating. The table below summarizes the relationships and test criteria.

Performance Verification Tests

The standard defines three mandatory tests for type classification, plus optional tests for extreme environments:

• Protection Against Rain and Snow: The enclosure is placed inside a controlled spray chamber. Rainfall is simulated at an intensity of 5–10 mm/min for 10 minutes. No water ingress is allowed at live parts.
• Hose-Down Test (Raintight): Water is directed through a 6.3 mm nozzle at 30 kPa from a distance of 3 m for 15 minutes. The enclosure is rotated to expose all seams. Water must not collect on live parts or degrade insulation.
• Immersion Test (Watertight): The enclosure is submerged at 1 m depth for 30 minutes. After removal, no water entry is permitted, and the dielectric withstand voltage must remain above 75% of the initial value.
• Low-Temperature Impact Test: Enclosures intended for outdoor use in cold climates are preconditioned at -40 °C for 4 hours, then struck with a 2.5 J energy impact. No cracking or penetration is allowed.

The standard also requires that all enclosures pass a dielectric voltage-withstand test after the water tests to verify insulation integrity. For raintight and watertight enclosures, a production-line air pressure test (100 kPa for 10 seconds) may be used as an alternative to testing every unit with water.

Implementation Highlights

Marking and Documentation

Every enclosure certified to CSA C22.2 No. 128-16 must be permanently marked with the manufacturer’s name, catalogue number, enclosure type (rainproof, raintight, or watertight), and the equivalent IP code (e.g., IPX5). The standard also requires the year of manufacture or a traceable lot code. For non-metallic enclosures, the marking must include the maximum operating temperature and the UV-resistance class.

Manufacturers must provide installation instructions that specify the maximum number of cable entries, the recommended tightening torque for cover fasteners, and any restrictions on field-modification of openings.

Field Assembly and Sealing

An important compliance note is that the enclosure’s protection level is only valid if the installer strictly follows the manufacturer’s instructions. Gaskets must be inspected for damage after wiring, and unused conduit openings must be sealed with approved plugs. The standard prohibits the use of field-applied silicone or other sealants unless permitted by the manufacturer’s documented procedure.

Compliance Notes

Certification and Marking Authority

In Canada, compliance with CSA C22.2 No. 128-16 is mandatory when the installation is required by the CE Code Part I to be rainproof, raintight, or watertight. Third-party certification by a Standards Council of Canada (SCC)-accredited organization (e.g., CSA Group, UL, Intertek) is the typical path to demonstrate compliance. The certification mark (e.g., CSA, cUL, ETL) along with the standard number must appear on the enclosure.

Harmonization with U.S. Standards

CSA C22.2 No. 128-16 is harmonized with UL 50 / UL 50E for many construction details, although the test parameters differ slightly (e.g., Canadian low-temperature impact energy vs. UL’s room temperature impact). For products intended for both Canadian and U.S. markets, manufacturers often use the bi-national standard CSA C22.2 No. 94.2-16 (which supersedes some parts of No. 128). However, No. 128 remains widely referenced for legacy and specialised outdoor enclosure needs.

Common Compliance Pitfalls

• Gasket degradation – Gaskets that are not UV-stabilized or are compressed beyond 80% will fail the hose-down test after thermal cycling.
• Corrosion at mounting feet – Metal enclosures with uncoated mounting brackets corrode rapidly; the standard requires all external metal parts to be corrosion-protected.
• Field modifications – Drilling additional holes on site voids the certification unless the enclosure is re-tested.
• Temperature derating – Non-metallic enclosures have a lower operating temperature limit; exceeding the marked maximum may cause deformation and seal failure.

The latest 2016 edition introduced a new requirement for a permanent drain hole in rainproof enclosures if water accumulation is deemed likely, but only if the drain path does not compromise the IP rating (e.g., one-way valve is used).

Frequently Asked Questions

© 2026 – Technical review of CSA C22.2 No. 128-16. This article is for informational purposes and does not replace the official standard. Always refer to the latest published edition for compliance requirements.