CSA C22.2 No. 4248.4-07 (2016): Class CC Fuseholders — Technical Overview and Compliance Guide

Scope and Application

CSA C22.2 No. 4248.4-07 (Reaffirmed 2016) is the Canadian national standard for Class CC fuseholders. It is part of the Fuseholders series under the C22.2 umbrella of standards developed by the Canadian Standards Association (CSA Group). This standard applies to fuseholders rated for use with Class CC fuses as defined in CSA C22.2 No. 4248.1 (General Requirements) and intended for installation in accordance with the Canadian Electrical Code, Part I.

Class CC fuseholders are distinguished by their compact footprint, rejection features that prevent insertion of lower‑voltage or lower‑interrupting‑rating fuses, and a high interrupting capacity (typically 200 kA at 600 V ac). They are designed for branch circuit protection in lighting, heating, motor control centers, and panelboards where space is at a premium but reliable overcurrent protection is critical.

Technical Requirements

Voltage and Current Ratings

The standard covers single‑pole and multi‑pole fuseholders rated up to 600 V ac and a maximum continuous current of 30 A. The fuseholder must be marked with its voltage rating and current rating, and the rating must accommodate the highest‑rated Class CC fuse that can be inserted.

Short‑Circuit Performance

Class CC fuseholders are subjected to short‑circuit tests at the assigned interrupting rating (typically 200 kA symmetrical) at rated voltage. The standard requires that after the test the fuseholder shows no rupture, no flashover between poles, and no damage that impairs its continued safe operation. These tests are conducted with the appropriate Class CC fuses installed.

Temperature Rise and Dielectric Strength

Temperature rise limits are specified for current‑carrying parts under continuous rated current (e.g., 65°C rise at 30 A). Dielectric voltage‑withstand tests are performed at 2200 V for fuseholders rated 600 V, with no breakdown or leakage current exceeding 0.5 mA.

Rejection Feature

A key requirement is the mechanical rejection feature that prevents a Class CC fuseholder from accepting fuses of a different Class (e.g., Class G, Class H, or Class J). This ensures that only fuses with the appropriate interrupting rating and voltage rating are used, maintaining system coordination and safety.

Typical Rating Combinations

The following table summarizes the standard ratings covered by CSA C22.2 No. 4248.4-07:

Implementation and Installation Highlights

When integrating Class CC fuseholders into electrical systems, several practical aspects deserve attention:

• Conductor sizing: Terminals are designed to accept copper or aluminum conductors from 14 AWG to 8 AWG, depending on the ampere rating. The standard specifies tightening torque values for reliable connections.
• Mounting orientation: Fuseholders may be installed in any orientation unless otherwise marked, but the manufacturer’s instructions should be followed to ensure proper heat dissipation.
• Fuse coordination: Class CC fuseholders are typically used in branch‑circuit applications where time‑delay characteristics (e.g., Class CC “CC” fuses) are required for motor starting or transformer inrush.
• Space saving: The compact 13⁄32 in × 1 in ferrule dimensions of Class CC fuses allow high‑density fuse blocks, often used in lighting panelboards and control panels.

For multi‑pole applications, the standard permits ganged assemblies where the common mounting base and interconnected wiring maintain the same pole‑to‑pole spacing. Such assemblies must pass the same short‑circuit and dielectric tests as individual poles.

Compliance and Certification Notes

Manufacturers seeking to certify Class CC fuseholders to CSA C22.2 No. 4248.4-07 must submit samples to an accredited laboratory (e.g., CSA Group or other recognized certification body). The evaluation includes all type tests described in the standard: temperature rise, dielectric voltage‑withstand, short‑circuit, and mechanical tests (such as fuse insertion/withdrawal cycles).

Key compliance points:

• Markings: Each fuseholder must be permanently marked with the manufacturer’s name or trademark, catalog number, voltage and current ratings, interrupting rating (if > 200 kA, else may reference “with Class CC fuse”), and the standard number (CSA C22.2 No. 4248.4).
• Field‑wiring terminals: Terminals must accept solid or stranded conductors and be suitable for the temperature rating of the connected wire (typically 60 °C or 75 °C).
• Factory inspection: Production‑line testing (e.g., dielectric withstand at reduced voltage) is required to ensure each unit meets minimum safety levels.
• Harmonization with UL: CSA C22.2 No. 4248.4-07 is technically identical to UL 4248-4 (Standard for Fuseholders – Part 4: Class CC). Products certified to either standard are accepted under the CSA/UL mutual recognition agreement for the U.S. and Canadian markets.

Finally, the standard has been reaffirmed in 2016 without technical changes, meaning the 2007 edition remains current. Any amendments or addenda issued after that date should be reviewed to ensure compliance with the latest safety requirements.

Last revised: 2026 — This article reflects the standard as of 2026.

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