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CSA C22.2 No. 66.1-06 (2013): General Requirements for Low-Voltage Transformers and Reactors
A Comprehensive Guide to Scope, Technical Specifications, and Compliance for Manufacturers and Engineers
Scope and Application
CSA C22.2 No. 66.1-06 (R2013) — formally Low-Voltage Transformers and Reactors – Part 1: General Requirements — is a key safety standard within the Canadian Electrical Code Part II (CE Code) framework. It covers dry-type transformers and reactors intended for use on systems with voltages not exceeding 600 V (nominal). The standard establishes unified construction, performance, and testing criteria to reduce the risk of fire, electric shock, and mechanical injury.
Tip: This standard is the general part of a two-part series. Part 2 provides specific requirements for particular transformer types (e.g., isolation, auto, control, and specialty transformers). Always reference the applicable Part 2 when it exists.
The standard applies to:
- Single-phase and polyphase transformers (general-purpose, control, isolation)
- Reactors (current-limiting, filter, and interphase types)
- Power supplies incorporating such transformers
Products covered must be installed in accordance with the Canadian Electrical Code Part I (CSA C22.1). The 2013 reaffirmation confirmed that the 2006 edition remains current without technical changes.
Key Technical Requirements
Insulation and Dielectric Strength
Insulation coordination is fundamental to the standard. All insulating materials must withstand specified dielectric tests, including basic impulse levels (BIL) and power-frequency withstand voltages. The following table summarises the routine dielectric test voltages for primary windings:
| Rated Operating Voltage (V) | Basic Insulation Level (kV peak) | Dielectric Test (V rms, 60 s) |
|---|---|---|
| 0 – 300 | 2.5 | 1,500 |
| 301 – 600 | 5.0 | 2,000 |
Clearances and creepage distances are defined based on pollution degree (typically PD2) and material group. Minimum distances are tabulated for voltages up to 600 V, with additional spacing for high-altitude installations above 2,000 m.
Important: For reinforced insulation, dielectric tests are performed at 125% of the basic test voltage. Manufacturers must ensure that all insulating materials are suitable for the intended temperature class (A, B, F, or H).
Temperature Rise Limits
Temperature rise measurements are taken under rated conditions (full load, normal ventilation). Limits depend on the insulation class and are given as rise above ambient (40 °C maximum ambient assumed).
| Insulation Class | Maximum Winding Temperature Rise (K) | Maximum Hot-Spot Temperature (°C) |
|---|---|---|
| Class A (105 °C) | 65 | 130 |
| Class B (130 °C) | 80 | 155 |
| Class F (155 °C) | 105 | 180 |
| Class H (180 °C) | 125 | 205 |
Core and enclosure temperature rises are also limited to avoid damage to adjacent materials. For transformers with multiple windings, the highest rise determines the class.
Short-Circuit Withstand and Mechanical Strength
Transformers must be designed to withstand the mechanical and thermal effects of a short circuit at the terminals for a duration corresponding to the clearing time of the upstream overcurrent protective device (typically 2 s). The standard references short-circuit testing per Table 4 of CSA C22.2 No. 66.1 or applicable Part 2.
Caution: Short-circuit testing is type-test only; compliance is demonstrated via design calculations or prototype testing. Manufacturers should validate that bracing, lead supports, and terminals can handle the computed forces.
Marking and Documentation
- Each unit shall bear a durable nameplate showing: manufacturer’s name, model, electrical ratings (kVA, voltage, current), frequency, insulation class, impedance, and compliance marking (e.g., “CSA C22.2 No. 66.1”).
- Installation instructions, wiring diagrams, and a list of replacement parts must accompany the product.
Implementation Highlights for Manufacturers
When designing a transformer for the Canadian market, adherence to CSA C22.2 No. 66.1-06 (2013) is mandatory for CSA certification. The following points streamline the compliance process:
- Define the insulation system: Use recognised insulation materials with appropriate thermal class. The entire winding assembly must be evaluated for compatibility.
- Perform dielectric design: Calculate creepage and clearance values based on operating voltage and pollution degree. Use the standard’s tables to verify minimum distances.
- Prove temperature rise: Conduct temperature tests on prototypes at rated load and worst-case ambient conditions. Consider forced cooling if natural convection cannot meet limits.
- Prepare for impedance and efficiency testing: The standard requires measurement of no-load and load losses, impedance voltage, and regulation.
Best Practice: Involve a recognised certification body (e.g., CSA Group, Intertek, UL) early in the design phase. Many laboratories offer pre-compliance reviews that reduce costly redesigns.
Compliance and Certification Notes
Certification to CSA C22.2 No. 66.1-06 (2013) is typically done under the SCC (Standards Council of Canada) accreditation framework. The standard is published by the Canadian Standards Association and is harmonised with corresponding UL standards (e.g., UL 5085 for low-voltage transformers) to facilitate cross-border acceptance.
Risk of Non-Compliance: Products that do not meet the requirements cannot legally bear the CSA mark nor be sold in Canada. Field inspections by provincial authorities may result in removal of non‑certified units.
Audit and Surveillance: Certified products are subject to periodic factory inspections and testing. Manufacturers must maintain a quality control program that covers incoming materials, in-process checks, and final testing. Any changes to design or materials require re‑evaluation by the certification body.
Record-Keeping: Test reports, design calculations, and drawings must be retained for at least five years after production cessation.
Note: As of 2026, the standard remains current without revision. Users should monitor the CSA website for potential updates, particularly concerning energy‑efficiency amendments or harmonisation with IEC 61558.
This article is based on the published edition of CSA C22.2 No. 66.1-06 (R2013) and reflects compliance guidance as of 2026. Always consult the official standard for complete requirements.
Q: What is the difference between CSA C22.2 No. 66.1 and IEC 61558-1?
A: While both cover general safety for low-voltage transformers, CSA C22.2 No. 66.1 is adapted for North American practice (60 Hz, voltage ratings in V rms, and specific installation rules per the CE Code). IEC 61558-1 is used internationally and includes additional provisions for different national wiring rules.
A: While both cover general safety for low-voltage transformers, CSA C22.2 No. 66.1 is adapted for North American practice (60 Hz, voltage ratings in V rms, and specific installation rules per the CE Code). IEC 61558-1 is used internationally and includes additional provisions for different national wiring rules.
Q: Does the standard apply to transformers over 600 V?
A: No. CSA C22.2 No. 66.1 is limited to primary voltages up to 600 V. Higher-voltage transformers fall under other standards, such as CSA C22.2 No. 47 (power transformers) or CSA C22.2 No. 257 (high-voltage instrument transformers).
A: No. CSA C22.2 No. 66.1 is limited to primary voltages up to 600 V. Higher-voltage transformers fall under other standards, such as CSA C22.2 No. 47 (power transformers) or CSA C22.2 No. 257 (high-voltage instrument transformers).
Q: Are there separate requirements for control transformers?
A: Yes. Part 2 of this series, CSA C22.2 No. 66.2, covers specific types including control, signalling, and isolating transformers. Manufacturers should verify if a Part 2 applies to their product.
A: Yes. Part 2 of this series, CSA C22.2 No. 66.2, covers specific types including control, signalling, and isolating transformers. Manufacturers should verify if a Part 2 applies to their product.
Q: How can I get certified to this standard?
A: Contact an SCC‑accredited certification body (e.g., CSA Group, Intertek, TÜV SÜD). They will review your design, conduct testing, and issue a Certificate of Compliance if all requirements are met.
A: Contact an SCC‑accredited certification body (e.g., CSA Group, Intertek, TÜV SÜD). They will review your design, conduct testing, and issue a Certificate of Compliance if all requirements are met.