BK/MDA-1-1/4 Equivalent & Substitute Parts

Part Overview

The BK/MDA-1-1/4 is a 1.25 A, 250 V AC ceramic cartridge fuse manufactured by Eaton Electronics Division. This component is classified as obsolete product status. The fuse operates with slow-blow response characteristics and requires a 3AB or 3AG holder for installation. Due to its obsolete classification, equivalent substitute parts from active product lines are necessary to maintain circuit protection functionality in applications requiring 1.25 A rated protection at 250 V AC.

Substiute Parts

BK/MDA-1-1/4

Eaton - Electronics DivisionIn Stock: 912BK/MDA-1-1/4 Datasheet

Current PartRFQ

BK/MDA-1-1/4-R

Eaton - Electronics DivisionIn Stock: 1009BK/MDA-1-1/4-R Datasheet

DirectRFQ

MDA-1-1/4-R

Eaton - Electronics DivisionIn Stock: 754MDA-1-1/4-R Datasheet

DirectRFQ

0001.2525

SCHURTER Inc.In Stock: 12940001.2525 Datasheet

DirectRFQ

03261.25HXP

Littelfuse Inc.In Stock: 127003261.25HXP Datasheet

DirectRFQ

03261.25MXP

Littelfuse Inc.In Stock: 69603261.25MXP Datasheet

DirectRFQ

03261.25VXP

Littelfuse Inc.In Stock: 121003261.25VXP Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the BK/MDA-1-1/4 is determined by the following critical parameters:

Primary Substitution Criteria:

• Current Rating: 1.25 A (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (exact match required)
• Fuse Type: Cartridge format (ceramic or glass acceptable)
• Response Time: Slow Blow (exact match required)
• Mounting Type: Requires Holder (exact match required)

Substitute Parts Identified:

Group 1: Eaton Active Equivalents

• BK/MDA-1-1/4-R
• MDA-1-1/4-R

Group 2: Littelfuse Ceramic Cartridge Fuses

• 03261.25HXP
• 03261.25MXP
• 03261.25VXP

Group 3: SCHURTER Glass Cartridge Fuse

• 0001.2525

All substitute parts maintain identical current rating, AC voltage rating, package dimensions, and mechanical compatibility with 3AB/3AG holders.

Parameter Comparison

Engineering Selection Recommendations

Primary Recommendation: Eaton Active Equivalents

The parts BK/MDA-1-1/4-R and MDA-1-1/4-R are direct active-status replacements from the original manufacturer. Both maintain identical electrical and mechanical specifications to the obsolete BK/MDA-1-1/4. The MDA-1-1/4-R variant includes CE, CSA, and UL approval certifications, providing broader regulatory compliance coverage. Both parts are ROHS3 compliant and available in bulk packaging.

Secondary Recommendation: Littelfuse 326 Series

The 03261.25HXP, 03261.25MXP, and 03261.25VXP ceramic cartridge fuses from Littelfuse provide functional equivalence with enhanced DC voltage rating (125 V DC versus unspecified DC rating on original). All three variants carry CE, CSA, PSE, and UL certifications. These parts feature higher melting I²t values (24 versus 1.5) and extended operating temperature range (-55°C to 125°C). Selection among these three variants depends on specific application requirements and inventory availability.

Alternative Recommendation: SCHURTER Glass Cartridge

The 0001.2525 glass cartridge fuse from SCHURTER provides functional substitution with different fuse element material. This part carries cURus certification and specifies DC voltage rating of 63 V. The glass construction and higher breaking capacity (1.5 kA AC, 20 kA DC) suit applications requiring enhanced fault current handling. Melting I²t is 2.5, intermediate between Eaton and Littelfuse variants.

Compliance Considerations:

All substitute parts are ROHS3 compliant and REACH unaffected. The original BK/MDA-1-1/4 is RoHS non-compliant; substitution with active-status parts addresses regulatory compliance requirements. Selection should prioritize parts with certifications matching the original application's regulatory environment (CE, CSA, UL, or PSE).

Frequently Asked Questions (FAQ)

Q: Can the BK/MDA-1-1/4 be directly replaced with BK/MDA-1-1/4-R or MDA-1-1/4-R?

A: Yes. Both Eaton active-status parts maintain identical current rating (1.25 A), AC voltage rating (250 V), fuse type (ceramic cartridge), response time (slow blow), and mechanical package (3AB, 3AG, 1/4" x 1-1/4"). Direct substitution is electrically and mechanically compatible.

Q: What is the difference between ceramic and glass cartridge fuses in this application?

A: Both ceramic (BK/MDA-1-1/4, Littelfuse 326 series) and glass (SCHURTER 0001.2525) cartridge fuses meet the 1.25 A, 250 V AC specification and fit 3AB/3AG holders. Ceramic fuses typically offer higher temperature ratings and different I²t characteristics. Glass fuses provide visual indication of element status. Selection depends on application-specific requirements for thermal performance and fault current handling.

Q: Are the Littelfuse 03261.25HXP, 03261.25MXP, and 03261.25VXP interchangeable?

A: Yes, for the specified 1.25 A, 250 V AC application. All three variants are ceramic cartridge fuses with identical current and AC voltage ratings, slow-blow response, 3AB/3AG package compatibility, and dimensions. Differences exist in DC voltage rating (125 V), melting I²t (24), and operating temperature range (-55°C to 125°C), but these do not affect AC-only applications matching the original specification.

Q: Does the SCHURTER 0001.2525 glass fuse provide equivalent protection?

A: The SCHURTER 0001.2525 provides equivalent protection for the 1.25 A, 250 V AC specification. It maintains identical current rating, AC voltage rating, slow-blow response, and 3AB/3AG holder compatibility. The glass construction and different melting I²t (2.5) represent material and thermal characteristic differences that do not prevent functional substitution in applications requiring 1.25 A protection at 250 V AC.

Q: What certifications should I verify when selecting a substitute?

A: The original BK/MDA-1-1/4 carries CSA and UL certifications. Substitute parts should maintain equivalent or broader certification coverage. The MDA-1-1/4-R includes CE, CSA, and UL certifications. Littelfuse variants (03261.25HXP, 03261.25MXP, 03261.25VXP) carry CE, CSA, PSE, and UL certifications. SCHURTER 0001.2525 carries cURus certification. Selection should match the regulatory requirements of the target application.

Q: Is RoHS compliance a factor in selecting a substitute?

A: Yes. The original BK/MDA-1-1/4 is RoHS non-compliant. All substitute parts listed are ROHS3 compliant. Applications subject to RoHS regulations require substitution with compliant parts. All active-status alternatives meet this requirement.

Q: Can I use these fuses in DC applications?

A: The original BK/MDA-1-1/4 specification does not explicitly state DC voltage rating. Littelfuse variants specify 125 V DC rating. SCHURTER 0001.2525 specifies 63 V DC rating. Eaton MDA-1-1/4-R does not specify DC rating. DC application suitability depends on the specific DC voltage and current requirements. Consult individual part datasheets for DC application compatibility.