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CSA C22.2 No. 245-17: Safety Requirements for Photovoltaic Combiner Boxes
Understanding the Canadian Standard for PV Combiner Box Construction, Testing, and Certification
Scope and Application of CSA C22.2 No. 245-17
CSA C22.2 No. 245-17, part of the Canadian Electrical Code Part II series, specifies the safety and performance requirements for photovoltaic (PV) combiner boxes used in utility-interconnected and standalone PV systems. These combiner boxes are enclosures that combine the outputs of multiple PV strings into a single output, incorporating overcurrent protection, disconnection means, and sometimes monitoring equipment.
The standard covers combiner boxes rated for voltages up to 1000 V DC (and up to 1500 V DC for some provisions) and a maximum current as specified by the manufacturer. It applies to both indoor and outdoor installations, defining constructional, electrical, mechanical, and environmental requirements. The standard does not cover inverters, charge controllers, or individual PV modules, but focuses specifically on the combiner box assembly.
Compliance with CSA C22.2 No. 245-17 is required for listing and certification of PV combiner boxes intended for the Canadian market. It harmonizes with UL 1741 in certain areas but includes specific Canadian deviations related to grounding, bonding, and ambient temperature ranges.
Technical Requirements
Electrical Construction
All current-carrying components must be rated for continuous operation at the maximum system voltage and current. The standard mandates minimum clearances and creepage distances based on the operating voltage and altitude. Table 1 summarizes key spacing requirements for uncoated PCBs and insulated conductors.
| Parameter | Requirement |
|---|---|
| Minimum creepage (basic insulation, ≤600 V) | 6.4 mm |
| Minimum creepage (reinforced, ≤600 V) | 12.7 mm |
| Minimum clearance (through air, ≤1000 V) | 8.5 mm |
| Dielectric withstand (60 Hz, 1 min) | 2200 V for circuits ≤600 V |
| Grounding conductor connection | ≥10 AWG copper, bonded to enclosure |
Overcurrent protective devices (OCPDs) within the combiner box must be listed and compatible with the system voltage and available short-circuit current. The standard requires short-circuit current rating (SCCR) marking and testing to withstand the possible fault current.
Mechanical Construction
Enclosures must meet the requirements of CSA C22.2 No. 94.1, “Enclosures for Electrical Equipment,” with an appropriate NEMA/CSA Type rating according to the intended location (e.g., Type 1 for indoor, Type 4X for outdoor). The standard specifies impact resistance, corrosion protection, and door/cover interlock for access to live parts.
Busbars and internal wiring must be secured to withstand vibration and thermal cycling. Terminals must be marked for torque values, and conductors must be sized according to Canadian Electrical Code (CE Code) requirements up to the ampacity of the overcurrent device.
Environmental and Performance Testing
Combiner boxes must undergo a series of tests including dielectric voltage withstand, insulation resistance, temperature rise under load, humidity conditioning, and rain/spray testing for outdoor enclosures. The standard includes UV exposure testing for enclosures and components exposed to sunlight.
Temperature rise limits are based on the insulation class of components: typically 60 K for Class 105 (A) materials, 80 K for Class 130 (B), etc. Ambient temperature is considered at 40°C for indoor and 50°C for outdoor with solar loading.
Implementation Highlights
Designers should choose components that are already certified to other CSA standards, such as CSA C22.2 No. 39 (fuses) or CSA C22.2 No. 14 (industrial control equipment). The use of recognized components simplifies compliance and reduces testing burden.
Design Tip: Ensure that internal wiring is kept short and neat to minimize impedance and improve heat dissipation. Use wire bending space guidelines from CE Code Tables 106 to 110 to facilitate installation and maintenance.
Particular attention must be given to the isolation of PV array positive and negative circuits from ground. The standard requires that the combiner box provide a means to disconnect the grounded conductor (typically negative) for maintenance, unless the system is designed to be ungrounded.
Warning: Many PV systems employ a grounded conductor (e.g., negative grounded). The combiner box must include a disconnecting means for that grounded conductor as required by CSA C22.1 (CE Code) Section 64. Omitting this is a common non-compliance.
The standard also addresses arc-fault protection compatibility. If the combiner box is used in a system requiring arc-fault circuit protection (AFCI), it must be compatible with the system design and not interfere with the fault detection.
Manufacturers must provide installation instructions that include torque values, wire type and size, conduit sizing, and information on the maximum overcurrent protection for the combined output.
Compliance Notes
To achieve certification, the combiner box must be tested by a recognized accredited agency such as CSA International, UL, or Intertek. The testing covers the full scope of the standard including construction review, component evaluation, and witnessed testing.
Success Path: Use a product certification plan early in the design phase. Submitting a pre-evaluation or preliminary construction report can identify issues before formal testing, shortening time to market.
It is important to note that CSA C22.2 No. 245-17 references many other standards, such as CSA C22.2 No. 94.1, CSA C22.2 No. 0 (General Requirements), and ANSI/UL 1741. A thorough understanding of these interconnected documents is essential.
Periodic re-evaluation and factory inspection are required by certification agencies. Marking must include the CSA mark, manufacturer identification, model, electrical ratings, wire size, and temperature class.
Safety Risk: Using a combiner box not listed to CSA C22.2 No. 245-17 in a Canadian installation may violate the CE Code and void insurance coverage. Always verify certification marks and consult with the local inspection authority.
The standard is updated periodically; the 2017 edition replaced the 2010 edition with clarifications on SCCR marking, temperature mapping, and requirements for 1500 V DC systems. Users should ensure they are working with the latest version.
Frequently Asked Questions
Q: Does CSA C22.2 No. 245-17 apply to AC combiner boxes?
A: No, the standard specifically covers DC combiner boxes for photovoltaic systems. AC combiner boxes fall under other standards such as CSA C22.2 No. 14 for industrial control panels.
A: No, the standard specifically covers DC combiner boxes for photovoltaic systems. AC combiner boxes fall under other standards such as CSA C22.2 No. 14 for industrial control panels.
Q: What is the maximum voltage covered by this standard?
A: The primary scope is for systems up to 1000 V DC. However, amendments in the 2017 edition include requirements for 1500 V DC combiner boxes, primarily for larger utility-scale installations. The clearances and creepage requirements increase for higher voltages.
A: The primary scope is for systems up to 1000 V DC. However, amendments in the 2017 edition include requirements for 1500 V DC combiner boxes, primarily for larger utility-scale installations. The clearances and creepage requirements increase for higher voltages.
Q: Can I use a UL 1741 listed combiner box in Canada?
A: UL 1741 is harmonized with CSA C22.2 No. 245-17 to some extent, but there are Canadian-specific differences, especially regarding grounding, bonding, temperature ranges, and marking language. A product listed only to UL 1741 may not meet the Canadian requirements. Look for a CSA mark or a C-US mark indicating compliance with Canadian standards.
A: UL 1741 is harmonized with CSA C22.2 No. 245-17 to some extent, but there are Canadian-specific differences, especially regarding grounding, bonding, temperature ranges, and marking language. A product listed only to UL 1741 may not meet the Canadian requirements. Look for a CSA mark or a C-US mark indicating compliance with Canadian standards.
Q: Are there special requirements for rooftop installation?
A: Yes, the standard requires that combiner boxes installed outdoors or in unconditioned spaces be rated for the appropriate environment (e.g., NEMA 3R/4/4X). Additionally, temperature rise testing accounts for solar irradiance. Roof-mounted combiner boxes should also meet CE Code requirements for accessibility and clearance.
A: Yes, the standard requires that combiner boxes installed outdoors or in unconditioned spaces be rated for the appropriate environment (e.g., NEMA 3R/4/4X). Additionally, temperature rise testing accounts for solar irradiance. Roof-mounted combiner boxes should also meet CE Code requirements for accessibility and clearance.
Last updated: 2026. This article provides a summary of CSA C22.2 No. 245-17; refer to the full standard for complete details.