Equivalent & Substitute Parts for BK/EFF-800MA

Part Overview

The BK/EFF-800MA is an 800 mA, 250 V AC/DC board mount fuse with fast blow response characteristics, manufactured by Eaton - Electronics Division. This component is classified as obsolete, necessitating identification of active equivalent alternatives for ongoing procurement and design applications. The fuse features through-hole radial mounting in a can-style vertical package with a breaking capacity of 50 A at rated voltage and operates across a temperature range of -55°C to 125°C.

Key Parameters

Parameter	Value
Current Rating	800 mA
Voltage Rating (AC)	250 V
Fuse Type	Board Mount (Cartridge Style Excluded)
Mounting Type	Through Hole
Package / Case	Radial, Can, Vertical
Response Time	Fast Blow
Breaking Capacity @ Rated Voltage	50 A
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution eligibility for the BK/EFF-800MA is determined by strict equivalence across the following parameters: current rating (800 mA), voltage rating (250 V AC), fuse type (board mount, non-cartridge), mounting type (through hole), package configuration (radial, can, vertical), and response time (fast blow). All identified substitute parts meet these core electrical and mechanical requirements. Variations in breaking capacity, melting I²t, DC cold resistance, operating temperature range, and approval agencies are documented but do not disqualify substitution when the primary functional parameters align.

Parameter Comparison

Parameter	BK/EFF-800MA (Eaton)	SR-5F-800MA-BK (Eaton)	37008000410 (Littelfuse)	MRF 800-BULK (Bel Fuse)
Current Rating (Amps)	800 mA	800 mA	800 mA	800 mA
Voltage Rating - AC	250 V	250 V	250 V	250 V
Fuse Type	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Package / Case	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical	Radial, Can, Vertical
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Breaking Capacity @ Rated Voltage	50 A	50 A	50 A	35 A
Operating Temperature Range	-55°C ~ 125°C	-40°C ~ 125°C	-40°C ~ 85°C	-55°C ~ 125°C
DC Cold Resistance (Ohms)	0.071	0.245	Not Provided	0.071
Melting I²t	0.21	1.5	0.12	0.4
Product Status	Obsolete	Active	Active	Active
RoHS Status	Not Provided	RoHS Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

SR-5F-800MA-BK (Eaton - Electronics Division): This substitute maintains manufacturer continuity with the original BK/EFF-800MA while offering active product status. It carries cULus approval and is RoHS compliant. The operating temperature range is constrained to -40°C ~ 125°C compared to the original -55°C ~ 125°C specification. DC cold resistance is elevated at 0.245 Ohms versus 0.071 Ohms in the original. Melting I²t is significantly higher at 1.5 compared to 0.21. Selection is appropriate for applications where the narrower temperature range and higher melting I²t are acceptable.

37008000410 (Littelfuse Inc., TR5® 370 Series): This substitute provides the broadest approval agency coverage, including CCC, cURus, SEMKO, and VDE certifications. It is ROHS3 compliant and REACH unaffected. The operating temperature range is limited to -40°C ~ 85°C, the most restrictive among all substitutes. Melting I²t is the lowest at 0.12. Breaking capacity matches the original at 50 A. Selection is appropriate for applications requiring extensive international compliance certifications and lower thermal stress characteristics.

MRF 800-BULK (Bel Fuse Inc., MRF Series): This substitute matches the original operating temperature range (-55°C ~ 125°C) and DC cold resistance (0.071 Ohms), providing the closest thermal and electrical performance profile. It carries AEC-Q200, CE, CSA, cULus, SEMKO, and VDE approvals with ROHS3 compliance and REACH unaffected status. Breaking capacity is reduced to 35 A compared to the original 50 A specification. Selection is appropriate for applications requiring extended temperature operation and automotive-grade reliability (AEC-Q200).

Frequently Asked Questions (FAQ)

Q: Can SR-5F-800MA-BK be used as a direct replacement for BK/EFF-800MA in all applications?

A: SR-5F-800MA-BK meets all core electrical and mechanical parameters. However, the operating temperature range is constrained to -40°C ~ 125°C versus the original -55°C ~ 125°C. Applications requiring operation below -40°C require evaluation of alternative substitutes. Additionally, the elevated DC cold resistance (0.245 Ohms vs. 0.071 Ohms) and melting I²t (1.5 vs. 0.21) may affect circuit behavior in sensitive applications.

Q: What is the significance of the breaking capacity difference in MRF 800-BULK?

A: MRF 800-BULK has a breaking capacity of 35 A compared to the original 50 A. Breaking capacity defines the maximum fault current the fuse can safely interrupt without rupturing or creating a hazard. Applications with fault currents exceeding 35 A require verification that this reduced capacity is acceptable for the circuit design.

Q: Which substitute offers the best compliance coverage?

A: 37008000410 (Littelfuse TR5® 370 Series) carries the most comprehensive approval agency certifications: CCC, cURus, SEMKO, and VDE. It is ROHS3 compliant and REACH unaffected. This makes it suitable for applications requiring international market compliance across multiple regulatory jurisdictions.

Q: Are there physical dimension differences between substitutes?

A: Yes. The original BK/EFF-800MA measures 0.329" Dia x 0.303" H (8.35mm x 7.70mm). SR-5F-800MA-BK measures 0.335" Dia x 0.319" H (8.50mm x 8.10mm), and 37008000410 measures 0.335" Dia x 0.315" H (8.50mm x 8.00mm). MRF 800-BULK matches the original at 0.329" Dia x 0.303" H (8.35mm x 7.70mm). PCB footprint compatibility must be verified for substitutes with larger dimensions.

Q: Which substitute is recommended for automotive applications?

A: MRF 800-BULK carries AEC-Q200 approval, indicating qualification for automotive-grade reliability and environmental stress testing. This substitute is appropriate for automotive circuit protection applications.

Q: What is the impact of melting I²t variations on circuit protection?

A: Melting I²t characterizes the thermal energy required to melt the fuse element. Lower values indicate faster response to overcurrent conditions. The original BK/EFF-800MA has a melting I²t of 0.21. 37008000410 offers the fastest response at 0.12, while SR-5F-800MA-BK offers the slowest at 1.5. Circuit designs sensitive to inrush current or transient overcurrent conditions should account for these differences.

Q: Can substitutes be intermixed in the same circuit board assembly?

A: All substitutes meet the core electrical and mechanical parameters for the BK/EFF-800MA. However, physical dimension variations and differences in DC cold resistance may affect circuit behavior if multiple fuses operate in parallel or in sensitive measurement circuits. Consistent use of a single substitute part number throughout an assembly is recommended.

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