KTK-4 Equivalent & Substitute Parts Reference

Part Overview

The KTK-4 is a 4A 600VAC fast-blow cartridge fuse manufactured by Eaton - Bussmann Electrical Division. This midget fuse (5AG, 10mm x 38mm) is designed for electrical and industrial applications requiring holder-based installation. The part maintains active product status with 808 units in current inventory. Equivalent and substitute parts are identified to support procurement flexibility, supply chain continuity, and application-specific voltage requirements across AC and DC operating conditions.

Substiute Parts

KTK-4

Eaton - Bussmann Electrical DivisionIn Stock: 834KTK-4 Datasheet

Current PartRFQ

0KLK004.T

Littelfuse Inc.In Stock: 8220KLK004.T Datasheet

DirectRFQ

KLKR004.T

Littelfuse Inc.In Stock: 1294KLKR004.T Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the KTK-4 are qualified based on the following critical parameters that determine functional interchangeability:

• Current Rating: 4A (exact match required)
• Voltage Rating - AC: 600 VAC (exact match required)
• Fuse Type: Cartridge (exact match required)
• Response Time: Fast Blow (exact match required)
• Package / Case: 5AG, 10mm x 38mm (exact match required)
• Physical Dimensions: 0.406" Dia x 1.500" L (exact match required)
• Mounting Type: Requires Holder (exact match required)

The identified substitutes meet all primary electrical and mechanical parameters. Variations in DC voltage ratings, breaking capacity, and approval agencies are secondary considerations that do not affect AC-rated circuit protection performance but may influence suitability for specific application environments.

Parameter Comparison

Engineering Selection Recommendations

All three parts maintain active product status and ROHS3 compliance, confirming current manufacturing support and environmental regulatory alignment.

The KTK-4 (Eaton) and 0KLK004.T (Littelfuse) are direct equivalents for AC-only applications. Both carry CSA and UL certifications and deliver 100kA breaking capacity at rated voltage. The 0KLK004.T provides additional DC capability (500 VDC) and QPL approval, making it suitable for dual-voltage environments without compromising AC performance.

The KLKR004.T (Littelfuse) offers enhanced AC breaking capacity (200kA) and CC class designation, supporting applications requiring higher fault current interruption. DC rating is reduced to 300 VDC. CE certification extends regulatory coverage for European markets.

Selection between substitutes depends on application voltage requirements (AC-only versus AC/DC), required breaking capacity, and regional compliance mandates. All three parts are mechanically and electrically compatible within their specified ratings.

Frequently Asked Questions (FAQ)

Q: Can the 0KLK004.T replace the KTK-4 in existing installations?

A: Yes. Both parts share identical AC voltage (600 VAC), current (4A), response time (fast blow), and physical dimensions (5AG, 10mm x 38mm). The 0KLK004.T is a direct functional equivalent for AC circuits. The additional 500 VDC rating does not affect AC performance.

Q: What is the difference between the 0KLK004.T and KLKR004.T?

A: Both are Littelfuse 4A 600VAC fast-blow cartridge fuses in 5AG package. The 0KLK004.T supports 500 VDC and 100kA AC breaking capacity. The KLKR004.T supports 300 VDC, offers 200kA AC breaking capacity, and carries CC class designation. Choose based on DC voltage requirements and fault current environment.

Q: Are all three parts compatible with the same holder?

A: Yes. All three parts use the 5AG midget cartridge package (10mm x 38mm) and require a compatible holder. Physical dimensions are identical: 0.406" diameter x 1.500" length.

Q: Which part should I select for a dual AC/DC application?

A: The 0KLK004.T supports both 600 VAC and 500 VDC, making it suitable for dual-voltage circuits. The KLKR004.T supports 600 VAC and 300 VDC. Select based on your DC voltage requirement.

Q: Do all parts meet the same certifications?

A: The KTK-4 carries CSA and UL approvals. The 0KLK004.T adds CE and QPL certifications. The KLKR004.T carries CE, CSA, and UL. All three meet North American standards; the Littelfuse options extend coverage to European and military procurement environments.

Q: What does "fast blow" mean for these fuses?

A: Fast-blow fuses respond quickly to overcurrent conditions, providing rapid circuit protection. All three parts share this response characteristic, ensuring consistent protection behavior across substitutions.