Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
CSA C22.2 NO. 355-18: Requirements for Portable Generator Sets and Transfer Switches
A comprehensive overview of the scope, technical requirements, and compliance pathways under the Canadian Electrical Code Part II
Introduction to CSA C22.2 NO. 355-18
CSA C22.2 NO. 355-18 is a national standard of Canada developed by the CSA Group under the Canadian Electrical Code Part II (CE Code). Published in 2018, this standard prescribes safety and performance requirements for portable generator sets, transfer switches, and related equipment intended for residential, commercial, and industrial standby or prime power applications. The standard applies to generator sets rated up to 15 kW (single-phase) or 11 kW (three-phase) and operating at voltages not exceeding 600 V. It also covers optional integral transfer switches and distribution panels commonly integrated into portable generator units.
The standard was created to address the growing market for portable emergency power sources and to harmonize Canadian requirements with existing U.S. standards (such as UL 2201) while reflecting the unique installation practices mandated by the CE Code. Compliance with CSA C22.2 No. 355-18 is required for certification and sale of such equipment in most Canadian provinces.
Tip: Although CSA C22.2 No. 355-18 is product-specific, manufacturers should always cross-reference the latest edition of the CE Code Part I (C22.1) for site installation requirements.
Scope and Equipment Categories
The standard covers two principal equipment categories:
1. Portable Generator Sets
These are engine-driven generator units that are not permanently fixed in place. They may be wheeled, skid-mounted, or self-contained within a weatherproof enclosure. The standard addresses generators fueled by gasoline, diesel, propane, natural gas, or dual-fuel configurations. Maximum continuous power is limited to 15 kW for single-phase and 11 kW for three-phase models.
2. Transfer Switches and Distribution Systems
Transfer switches that are packaged with or offered as accessories for portable generators are also within scope. These include manual and automatic transfer switches rated for generator compatibility, as well as integral load centres providing branch circuit protection. Stand-alone transfer switches that are not physically integrated with a generator are not covered by this standard; they fall under CSA C22.2 No. 14.
The standard excludes:
- Stationary generators intended as part of a permanently installed system
- Generator sets rated above 15 kW
- Inverter-based generator systems that require a separate energy storage component
- Transfer switches designed for continuous grid interconnection (e.g., utility paralleling)
| Equipment Type | Rated Power | Fuel Types | In Scope |
|---|---|---|---|
| Portable generator set (single-phase) | ≤ 15 kW | Gasoline, diesel, propane, natural gas, dual-fuel | Yes |
| Portable generator set (three-phase) | ≤ 11 kW | Gasoline, diesel, propane, natural gas, dual-fuel | Yes |
| Inverter generator with battery storage | Any | N/A | No (see C22.2 No. 340) |
| Stand-alone transfer switch (non-integral) | — | — | No (see C22.2 No. 14) |
Technical Requirements
The technical provisions of CSA C22.2 No. 355-18 are divided into several clauses that address construction, electrical performance, thermal management, and safety protection. Key requirements are highlighted below.
2.1 Enclosure and Mechanical Construction
Generator enclosures must be constructed of corrosion-resistant materials or provided with a suitable protective coating. All openings must be screened to prevent entry of rodents and debris. The standard mandates a minimum degree of ingress protection of IP23 for outdoor-rated units (ref. CSA C22.2 No. 94.2). Enclosures must also withstand a static load test of 135% of the maximum expected wind load for the intended installation region.
2.2 Electrical Grounding and Bonding
The generator neutral must be bonded to the frame through a removable bonding jumper to permit configuration for either separately derived or non-separately derived systems. Where an integral transfer switch is provided, the neutral-to-ground connection must comply with CE Code Part I Rule 10-212. The generator must include a grounding terminal that is clearly marked with the symbol per CSA C22.2 No. 0.4.
2.3 Overcurrent and Overload Protection
Each generator circuit must be protected by a branch-rated overcurrent device located within the generator enclosure or as part of the integral distribution panel. The standard requires that the generator set be capable of supplying rated current continuously for at least 4 hours without exceeding allowable temperature rises as defined in Table 2 below.
| Component | Temperature Rise (K) |
|---|---|
| Copper windings (Class F) | 105 |
| Iron core (no adjacent windings) | 80 |
| Enclosure surface (accessible) | 60 |
| Terminals and switches | 65 |
| Internal wiring (PVC-insulated) | 50 |
2.4 Safety Features
Control and Interlocks: Generators must be equipped with a manual shut-off that disables the engine. If an electric start is provided, the starter circuit must have a neutral safety switch. Automatic transfer switches must include a time delay to prevent rapid restarts after power restoration. Fuel System: All fuel lines must be secured with double clamps at each connection. Gasoline generators must include a fire-test-rated fuel shut-off valve per UL 2201.
Warning: The standard requires that all external metallic parts that could become energized under fault conditions be bonded to the generator frame with a conductor of size at least equal to the supply neutral. Failure to comply may lead to electric shock hazards.
2.5 Testing and Performance Verification
Certification testing under CSA C22.2 No. 355-18 includes the following:
- Dielectric voltage-withstand test: 1000 V plus twice rated voltage applied between live parts and metal enclosure.
- Protection against overload: The unit must clear a 125% overload within 2 minutes without fire or shock risk.
- Stability test: The generator must not tip when tilted to 10° from horizontal in any direction.
- Fuel spill test: The generator is rotated 90° from its normal operating position; no fuel leakage is permitted.
Success: Many manufacturers find that engaging a CSA-accredited testing laboratory early in the design phase significantly reduces the time needed to achieve certification, especially when performing the extensive thermal and overload runs.
Implementation and Installation Recommendations
To facilitate smooth uptake of equipment certified to CSA C22.2 No. 355-18, installers and specifiers should note:
- Generator sets must be used with a listed transfer switch that complies with the CE Code Part I requirements for service entrance equipment where applicable.
- Field wiring to the generator must be in accordance with the manufacturer’s instructions and CE Code Part I, including appropriate sizing for voltage drop and ground fault protection.
- For residential standby applications, the generator should be installed such that exhaust gases are directed away from building air intakes, windows, and doors.
Compliance and Certification Notes
Product certification to CSA C22.2 No. 355-18 is typically part of the CSA Mark program. The following points are essential for compliance:
- File review: A full component list and wiring diagram must be submitted before testing.
- Factory inspections: Annual follow-up inspections are required to maintain certification.
- Modifications: Any change in engine make/model, alternator design, or control module will necessitate a new evaluation.
- Marking: Each generator must bear a nameplate specifying the model, power rating, fuel type, ambient temperature limits, and the CSA Mark of conformity.
Important: CSA C22.2 No. 355-18 is not intended to replace the requirements of the CE Code Part I. Even when a certified product is used, a final installation must be inspected by the local authority having jurisdiction (AHJ) to ensure compliance with all applicable rules.
Frequently Asked Questions
Q: Does CSA C22.2 No. 355-18 apply to generator sets sold for export outside Canada?
A: No. This standard is developed specifically for the Canadian market. Export products should comply with the respective local standards (e.g., UL 2201 for the U.S., EN 12601 for Europe).
A: No. This standard is developed specifically for the Canadian market. Export products should comply with the respective local standards (e.g., UL 2201 for the U.S., EN 12601 for Europe).
Q: Can a generator that meets CSA C22.2 No. 355-18 be used as a primary power source for an entire building?
A: The standard permits continuous rated operation, but local electrical codes may require a transfer switch and possibly a permanent installation permit. For full building backup, a larger stationary generator (above 15 kW) with load management is often recommended.
A: The standard permits continuous rated operation, but local electrical codes may require a transfer switch and possibly a permanent installation permit. For full building backup, a larger stationary generator (above 15 kW) with load management is often recommended.
Q: Are there any special requirements for generators equipped with automatic transfer switches?
A: Yes. In addition to meeting all generator requirements, the automatic transfer switch portion must also comply with CSA C22.2 No. 14 for transfer switch equipment and be tested for a minimum of 5000 mechanical operations and 1000 full-load electrical operations.
A: Yes. In addition to meeting all generator requirements, the automatic transfer switch portion must also comply with CSA C22.2 No. 14 for transfer switch equipment and be tested for a minimum of 5000 mechanical operations and 1000 full-load electrical operations.
Q: What is the status of revisions to this standard?
A: CSA C22.2 No. 355-18 was published in 2018. A maintenance cycle typically occurs every five years. Stakeholders should monitor the CSA Group website for proposed amendments or new editions.
A: CSA C22.2 No. 355-18 was published in 2018. A maintenance cycle typically occurs every five years. Stakeholders should monitor the CSA Group website for proposed amendments or new editions.
© 2026 CSA Standards Portfolio. This article is for informational purposes and does not substitute for the full standard text.