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Understanding CAN/CSA E60335-2-35-01: Safety Requirements for Instantaneous Water Heaters
A comprehensive guide to the Canadian adoption of IEC 60335-2-35 for electric instantaneous water heaters – scope, technical mandates, and compliance pathways
Electric instantaneous water heaters are widely used in residential and light commercial applications. To ensure their safe operation in the Canadian market, manufacturers must comply with the national adoption of the international safety standard – CAN/CSA E60335-2-35-01. This article provides an in-depth analysis of the standard’s scope, essential technical requirements, implementation strategies, and compliance processes, helping stakeholders navigate certification and meet regulatory obligations.
Scope and Application
CAN/CSA E60335-2-35-01 applies to the safety of electric instantaneous water heaters for household and similar purposes, with a rated voltage not exceeding 250 V for single-phase appliances and 480 V for other appliances. The standard covers appliances intended for normal household use and also those that may be used by laymen in shops, light industry, and on farms. Unless specifically excluded, the standard also applies to appliances intended for outdoor use.
It does not cover:
- Appliances intended exclusively for industrial purposes;
- Appliances intended to be used in locations where special conditions prevail, such as the presence of a corrosive or explosive atmosphere (dust, vapor, or gas);
- Storage water heaters, which fall under IEC 60335-2-21.
The standard is read in conjunction with the general requirements of IEC 60335-1 (adopted as CAN/CSA E60335-1), which provides foundational safety principles for household electrical appliances.
Important: As a National Standard of Canada, CAN/CSA E60335-2-35-01 supersedes any conflicting local codes unless explicitly noted. Manufacturers should always confirm the latest edition with CSA Group.
Key Technical Requirements
The standard establishes detailed safety criteria covering electrical, mechanical, thermal, and fire hazards. Below are the core technical mandates:
General Construction and Marking
Appliances must be constructed so that they are safe under both normal and reasonably foreseeable abnormal conditions. The standard requires that all parts are adequately protected against corrosion, and that materials used in the water circuit are resistant to the water quality typical for potable water. Markings must include rated voltage, power input, water connection pressure limits, and any specific installation instructions.
Protection Against Electric Shock
Parts of opposite polarity must be separated by at least 3 mm clearance for basic insulation and at least 6 mm for reinforced insulation, measured after environmental tests. Leakage current at operating temperature must not exceed 0.5 mA per kW rated input (with a maximum of 3.5 mA). Dielectric strength tests require a 1250 V AC (or 1750 V DC) test voltage for basic insulation and 3750 V AC for reinforced insulation, with no breakdown.
Temperature Rise and Overheat Protection
The standard limits temperature rises on accessible surfaces (e.g., handles, knobs) and internal components. For instantaneous water heaters, the water outlet temperature must not exceed 85°C under any condition. The appliance must incorporate at least one non-self-resetting thermal cut-out (manual reset) to prevent overheating if the thermostat fails.
Resistance to Moisture and Ingress
Appliances must be tested for moisture resistance using an IPX1 (drip-proof) or higher rating, depending on the manufacturer’s declared installation environment. After the moisture test, insulation resistance must be no less than 2 MΩ, and the dielectric strength test must be passed.
Abnormal Operation and Mechanical Hazards
The standard requires the appliance to be safe in the event of blocked water flow, loss of prime, or failure of electrical components (e.g., short circuit of semiconductors). The enclosure must be evaluated for impact resistance (IK rating) and for protection against moving parts. All electrical connections must withstand a pull force of 50 N without loosening.
Compliance Tip: Many requirements are fulfilled by referencing the tests of IEC 60335-1. For example, the glow-wire test for plastic parts (IEC 60695-2-11) is adopted, requiring a test temperature of 650°C for parts supporting live components and 550°C for other flammable parts.
Implementation Highlights for Manufacturers
Successful implementation of CAN/CSA E60335-2-35-01 requires careful integration of safety into the product design process. Key points include:
| Requirement Area | Design Consideration | Typical Verification Method |
|---|---|---|
| Electric shock protection | Proper creepage and clearance distances for PCBs, connectors, and terminals; use of reinforced insulation around heating elements | Measurement, dielectric test (1250 V / 3750 V) |
| Temperature control | Select thermostats and thermal cut‑outs with adequate rating; ensure placement in intimate contact with heater body | Temperature rise test, abnormal operation test with disabled thermostat |
| Water ingress | Seal all cable entries; use gaskets or potting compounds for enclosure; locate PCB above possible leaks | IPX1/IPX4 test, insulation resistance after test |
| Mechanical strength | Use metal brackets for heavy components; ensure enclosure can pass impact test (0.5 J) | Impact test, pull force test on terminals |
| Wire safety | Internal wiring must be rated for the highest temperature encountered; use cables with CSA/UL marking | Wire temperature test, flame test (VW-1 or FT1) |
For manufacturers using components certified to other standards (e.g., UL), it is essential to verify that the component ratings and test methods meet the specific requirements of the Canadian adoption. Differences in supply voltage (120/240 V) and ambient temperature ranges may mandate additional testing.
Caution: Impeller or flow switch materials must be selected for the maximum water temperature they may encounter, including during thermostat failure. Plastics used in these parts need a minimum relative thermal index (RTI) of 75°C when wet.
Compliance and Certification Process
To demonstrate compliance with CAN/CSA E60335-2-35-01, manufacturers typically engage a recognized certification body such as CSA Group, Intertek, or UL. The process involves:
- Documentation submission: Bill of materials, wiring diagram, critical component list, marking details, and instruction manual (English and French required for Canada).
- Construction inspection: Review of clearances, insulation, and mechanical assembly by a test engineer.
- Type testing: Complete execution of all applicable tests: input test, heating test, leakage current, moisture resistance, normal and abnormal operation, endurance (for switches and controls), and stability.
- Factory inspection (initial and periodic): Verification of production line conformity, quality controls, and traceability.
- Issuance of certification and inclusion of the CSA mark or equivalent.
Testing should be performed on units representative of the final production model. Any change in critical components or materials may require an extension of the certification.
Regulatory Note: In Canada, electrical safety standards are mandated by provincial authorities (e.g., Ontario ESA, Quebec RBQ). While CSA certification is voluntary, most jurisdictions require a recognized certification mark (CSA, cUL, cETL, etc.) as evidence of compliance. Always verify local adoption status.
The certification process also includes verification of the instruction manual. Manuals must contain installation, operation, and maintenance instructions that align with the standard’s requirements, including warnings about water pressure limits and electrical disconnection.
Common Compliance Pitfalls
- Creepage distances: Insufficient clearance between mains and low‑voltage parts (e.g., sensing electronics) – may require slots or insulating barriers.
- Thermal cut‑out selection: Use of a self‑resetting cut‑out where a non‑self‑resetting device is required for overheat protection.
- Waterproofing: Inadequate sealing around wire entry points leading to moisture ingress and failure of dielectric test.
- Marking: Missing or incomplete rating markings, especially water pressure range and electrical ratings.
Footer: This article is based on CAN/CSA E60335-2-35-01 as available in 2026. For the most current version, refer to the official publication from CSA Group.
Q: What is the difference between CAN/CSA E60335-2-35-01 and IEC 60335-2-35?
A: CAN/CSA E60335-2-35-01 is the Canadian national adoption of IEC 60335-2-35. It is technically identical but includes national deviations that address Canadian supply voltages (usually 120/240 V) and climatic conditions. Additionally, the standard may reference Canadian electrical codes and bilingual labeling requirements.
A: CAN/CSA E60335-2-35-01 is the Canadian national adoption of IEC 60335-2-35. It is technically identical but includes national deviations that address Canadian supply voltages (usually 120/240 V) and climatic conditions. Additionally, the standard may reference Canadian electrical codes and bilingual labeling requirements.
Q: Does the standard cover both commercial and residential instantaneous water heaters?
A: The primary scope is household and similar use. Commercial applications that fall under “similar purposes” (e.g., light industry, shops) can be included as long as normal persons operate them. Dedicated industrial heaters are excluded.
A: The primary scope is household and similar use. Commercial applications that fall under “similar purposes” (e.g., light industry, shops) can be included as long as normal persons operate them. Dedicated industrial heaters are excluded.
Q: Are there specific requirements for point-of-use versus whole-house heaters?
A: The standard applies to all electric instantaneous water heaters regardless of capacity, as long as they heat water on demand. However, larger units may require additional testing for stability and mechanical strength (e.g., wall‑mounting brackets).
A: The standard applies to all electric instantaneous water heaters regardless of capacity, as long as they heat water on demand. However, larger units may require additional testing for stability and mechanical strength (e.g., wall‑mounting brackets).
Q: How often is the standard revised?
A: CSA Group typically reviews and updates adopted IEC standards every 5–7 years. Manufacturers should monitor the IEC 60335-2-35 revision status and any proposed CSA deviations. As of 2026, the active edition listed by CSA is the 2001 version with possible amendments.
A: CSA Group typically reviews and updates adopted IEC standards every 5–7 years. Manufacturers should monitor the IEC 60335-2-35 revision status and any proposed CSA deviations. As of 2026, the active edition listed by CSA is the 2001 version with possible amendments.