BK/ETF-5 Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The BK/ETF-5 is a 5 A, 277 V AC/DC board mount fuse manufactured by Eaton - Electronics Division. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing maintenance, repair, and new design applications. The fuse features a radial, can-style vertical mounting configuration with slow-blow response characteristics, designed for through-hole PCB assembly.

Substiute Parts

BK/ETF-5

Eaton - Electronics DivisionIn Stock: 910BK/ETF-5 Datasheet

Current PartRFQ

SR-5-5A-BK

Eaton - Electronics DivisionIn Stock: 1282SR-5-5A-BK Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BK/ETF-5 is determined by the following critical parameters:

Current Rating: The substitute part must maintain the 5 A current rating to ensure proper circuit protection and prevent nuisance trips or inadequate protection.

Mounting Type & Package: Both the main part and substitute must use through-hole mounting with radial, can-style vertical configuration to ensure mechanical compatibility with existing PCB layouts.

Fuse Type: Board mount cartridge-style exclusion applies to both parts, maintaining consistency in form factor and installation method.

Response Time: Slow-blow characteristic must be preserved to match the original circuit design intent and prevent false triggering during inrush conditions.

Voltage Rating: The substitute part operates at 250 V AC, which is lower than the original 277 V rating. This represents a voltage derating and is acceptable only in applications where the actual operating voltage does not exceed 250 V AC.

The SR-5-5A-BK meets these core substitution criteria while offering active product status and broader international compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

The SR-5-5A-BK serves as a direct functional substitute for the obsolete BK/ETF-5 based on the following engineering criteria:

Current and Mounting Compatibility: Both parts maintain identical 5 A current ratings and through-hole radial mounting configurations, ensuring electrical and mechanical interchangeability at the PCB level.

Voltage Derating Consideration: The SR-5-5A-BK operates at 250 V AC versus the original 277 V AC rating. Selection of this substitute is appropriate only when the actual circuit operating voltage does not exceed 250 V AC. Applications requiring the full 277 V rating cannot use this substitute.

Product Status and Availability: The SR-5-5A-BK is active production status with 1232 units in stock, compared to the obsolete BK/ETF-5 with limited remaining inventory of 862 units. This ensures long-term supply continuity.

Compliance and Certifications: The SR-5-5A-BK carries expanded international certifications including CCC, cULus, KC-MARK, PSE, SEMKO, and VDE, providing broader regulatory acceptance across global markets. The original part holds SEMKO and UL certifications.

Thermal Operating Range: The SR-5-5A-BK operates within -40°C to 85°C, which is narrower than the original -55°C to 125°C range. Applications requiring extended low-temperature operation below -40°C or high-temperature operation above 85°C must retain the original BK/ETF-5 specification.

Breaking Capacity: The SR-5-5A-BK provides 50 A breaking capacity at rated voltage, lower than the original 100 A. This reduction is acceptable for standard board-mount fuse applications but must be verified against circuit fault current requirements.

Frequently Asked Questions (FAQ)

Q: Can the SR-5-5A-BK replace the BK/ETF-5 in all applications?

A: No. The SR-5-5A-BK is suitable only for applications where the operating voltage does not exceed 250 V AC and the ambient temperature remains within -40°C to 85°C. Applications requiring 277 V operation or extended temperature ranges must use the original BK/ETF-5 or identify alternative parts rated for those conditions.

Q: What is the significance of the voltage rating difference between 277 V and 250 V?

A: The 277 V rating on the BK/ETF-5 indicates the maximum voltage at which the fuse is designed to safely interrupt a fault current. The SR-5-5A-BK at 250 V represents a lower voltage class. Using a lower-rated fuse in a higher-voltage circuit creates a safety risk. Verify actual circuit voltage before substitution.

Q: Are the physical dimensions compatible between these two parts?

A: The parts are similar but not identical. The BK/ETF-5 measures 0.329" diameter × 0.303" height (8.35mm × 7.70mm), while the SR-5-5A-BK measures 0.335" diameter × 0.319" height (8.50mm × 8.10mm). The SR-5-5A-BK is slightly larger. Verify PCB footprint clearance before installation.

Q: What does "slow-blow" response time mean?

A: Slow-blow fuses tolerate temporary inrush currents without opening, responding only to sustained overcurrent conditions. Both the BK/ETF-5 and SR-5-5A-BK share this characteristic, maintaining circuit behavior consistency.

Q: Why does the SR-5-5A-BK have lower breaking capacity (50 A vs. 100 A)?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt. The SR-5-5A-BK's 50 A breaking capacity is adequate for standard board-mount applications. Verify that the circuit's maximum fault current does not exceed this value before substitution.

Q: What certifications should I consider for regulatory compliance?

A: The SR-5-5A-BK holds CCC, cULus, KC-MARK, PSE, SEMKO, and VDE certifications, providing compliance for North American (cULus), European (VDE), Asian (CCC, KC-MARK, PSE), and international (SEMKO) markets. Select based on your target market requirements.

Q: Is the SR-5-5A-BK RoHS compliant?

A: Yes, the SR-5-5A-BK is ROHS3 compliant and REACH unaffected, meeting environmental and hazardous substance restrictions for EU and global markets.