BK/EFF-1 Board Mount Fuse Equivalent & Substitute Parts

Part Overview

The BK/EFF-1 is a 1 A, 250 V AC/DC board mount fuse manufactured by Eaton - Electronics Division, designed for through-hole radial mounting in vertical orientation. This component is classified as obsolete, necessitating identification of active equivalent parts for ongoing design support and procurement continuity. Substitute parts must maintain identical electrical ratings, mechanical compatibility, and functional performance characteristics to ensure direct replacement capability without circuit redesign.

Substiute Parts

BK/EFF-1

Eaton - Electronics DivisionIn Stock: 1060BK/EFF-1 Datasheet

Current PartRFQ

SR-5F-1A-BK

Eaton - Electronics DivisionIn Stock: 809SR-5F-1A-BK Datasheet

SimilarRFQ

MRF 1-AMMO

Bel Fuse Inc.In Stock: 757MRF 1-AMMO Datasheet

DirectRFQ

MRF 1-BULK

Bel Fuse Inc.In Stock: 1831MRF 1-BULK Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BK/EFF-1 is determined by strict alignment with the following mandatory parameters:

Electrical Parameters (Non-Negotiable):

• Current Rating: 1 A
• Voltage Rating (AC): 250 V
• Response Time: Fast Blow
• Fuse Type: Board Mount (Cartridge Style Excluded)

Mechanical Parameters (Non-Negotiable):

• Mounting Type: Through Hole
• Package / Case: Radial, Can, Vertical
• Size / Dimension: 0.329" Dia x 0.303" H (8.35mm x 7.70mm)

Secondary Parameters (Acceptable Variance):

• Breaking Capacity: Substitute must equal or exceed 50 A
• DC Cold Resistance: Minor variations acceptable within circuit tolerance
• Operating Temperature Range: Substitute must encompass or exceed -55°C ~ 125°C
• Melting I²t: Variations permitted if electrical ratings remain identical

All identified substitutes maintain identical electrical and mechanical specifications, ensuring direct PCB replacement without modification to mounting holes, trace routing, or circuit design.

Parameter Comparison

Engineering Selection Recommendations

SR-5F-1A-BK (Eaton - Electronics Division): This substitute maintains identical electrical ratings and fast-blow response characteristics. Physical dimensions show minor variance (0.335" Dia x 0.319" H versus 0.329" Dia x 0.303" H), requiring PCB footprint verification before implementation. Operating temperature range is -40°C ~ 125°C, which does not extend to the lower -55°C limit of the original part. This substitute is suitable for applications operating within -40°C ~ 125°C. Product status is active with established supply chain. Certifications include cULus and PSE. RoHS compliance is confirmed.

MRF 1-AMMO (Bel Fuse Inc.): This substitute provides identical electrical ratings, response time, and mechanical dimensions (0.329" Dia x 0.303" H). Operating temperature range matches the original specification (-55°C ~ 125°C). Breaking capacity is 35 A, which is lower than the original 50 A rating. Comprehensive certifications include AEC-Q200, CE, CSA, cULus, PSE, SEMKO, and VDE. ROHS3 compliance and REACH unaffected status are confirmed. Packaging is Tape & Box (TB). This substitute is suitable for applications where the 35 A breaking capacity is acceptable.

MRF 1-BULK (Bel Fuse Inc.): This substitute is functionally identical to MRF 1-AMMO with identical electrical ratings, response time, mechanical dimensions, and operating temperature range (-55°C ~ 125°C). Breaking capacity is 35 A. Certifications and compliance status are identical to MRF 1-AMMO. Packaging is bulk format. Highest inventory availability (1735 Pcs) supports procurement continuity. This substitute is suitable for applications where the 35 A breaking capacity is acceptable and bulk packaging is preferred.

Frequently Asked Questions (FAQ)

Q: Can SR-5F-1A-BK be used as a direct replacement for BK/EFF-1?

A: SR-5F-1A-BK maintains identical electrical ratings (1 A, 250 V AC, fast-blow response). Physical dimensions show minor variance: 0.335" Dia x 0.319" H versus 0.329" Dia x 0.303" H. PCB footprint compatibility must be verified. Operating temperature range is -40°C ~ 125°C, which does not extend to -55°C. This substitute is suitable only for applications operating within -40°C ~ 125°C.

Q: What is the difference between MRF 1-AMMO and MRF 1-BULK?

A: Both parts are electrically and mechanically identical. The difference is packaging format: MRF 1-AMMO is supplied in Tape & Box (TB) format, while MRF 1-BULK is supplied in bulk format. Selection depends on procurement and assembly process requirements. MRF 1-BULK offers higher inventory availability (1735 Pcs versus 677 Pcs).

Q: Why do the Bel Fuse MRF parts have a lower breaking capacity (35 A) than the original BK/EFF-1 (50 A)?

A: Breaking capacity is a distinct parameter from current rating. Both the original part and MRF substitutes are rated for 1 A continuous current and 250 V AC. The breaking capacity specification indicates the maximum fault current the fuse can safely interrupt. The 35 A breaking capacity of MRF parts is sufficient for standard board mount fuse applications. Circuit design must confirm that available fault current does not exceed 35 A.

Q: Are all substitute parts RoHS compliant?

A: SR-5F-1A-BK is RoHS Compliant. MRF 1-AMMO and MRF 1-BULK are ROHS3 Compliant. The original BK/EFF-1 RoHS status is not specified. All active substitutes meet current RoHS requirements.

Q: Which substitute has the best certification coverage?

A: MRF 1-AMMO and MRF 1-BULK (both Bel Fuse Inc.) provide the most comprehensive certification coverage: AEC-Q200, CE, CSA, cULus, PSE, SEMKO, and VDE. These certifications support automotive, European, North American, and international applications. SR-5F-1A-BK certifications are limited to cULus and PSE.

Q: Can I use these substitutes interchangeably in the same design?

A: MRF 1-AMMO and MRF 1-BULK are fully interchangeable (identical electrical and mechanical specifications, different packaging only). SR-5F-1A-BK requires PCB footprint verification due to dimensional variance and is suitable only for -40°C ~ 125°C applications. The three substitutes are not universally interchangeable; selection depends on specific application requirements.

Q: What is the significance of the Melting I²t parameter?

A: Melting I²t indicates the thermal energy required to melt the fuse element. BK/EFF-1 has Melting I²t of 0.36, while substitutes range from 0.7 to 2.6. This parameter affects fuse response characteristics under transient current conditions. All parts maintain identical 1 A current rating and fast-blow response time, ensuring functional equivalence for standard applications.

Q: Is DC Cold Resistance variation significant?

A: BK/EFF-1 has DC Cold Resistance of 0.055 Ohms. SR-5F-1A-BK is 0.171 Ohms, while MRF parts are 0.057 Ohms. For most applications, this variation is negligible. Circuit designs with tight voltage drop budgets should verify that the substitute resistance does not exceed circuit tolerance limits.