BK/MDQ-3/8 Equivalent & Substitute Parts

Part Overview

The BK/MDQ-3/8 is a 375 mA, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Eaton - Electronics Division. This fuse is designed for use in 3AB and 3AG holders with dimensions of 1/4" x 1-1/4" (6.35mm x 31.75mm). The part is currently active in production with 1014 pieces in stock. Substitute parts are necessary when the primary part becomes unavailable, when alternative compliance certifications are required, or when design revisions call for components with improved electrical characteristics or updated regulatory compliance status.

Substiute Parts

BK/MDQ-3/8

Eaton - Electronics DivisionIn Stock: 1106BK/MDQ-3/8 Datasheet

Current PartRFQ

BK/MDL-3/8-R

Eaton - Electronics DivisionIn Stock: 1206BK/MDL-3/8-R Datasheet

Parametric EquivalentRFQ

0034.5217

SCHURTER Inc.In Stock: 9910034.5217 Datasheet

Parametric EquivalentRFQ

0313.375HXP

Littelfuse Inc.In Stock: 10580313.375HXP Datasheet

Parametric EquivalentRFQ

0313.375MXP

LittelfuseIn Stock: 37180313.375MXP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BK/MDQ-3/8 is determined by strict equivalence across the following parameters:

• Current Rating: 375 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (exact match required)
• Breaking Capacity @ Rated Voltage: 35A (exact match required)
• Size / Dimension: 0.250" Dia x 1.250" L (exact match required)

All substitute parts listed meet these electrical and mechanical parameters. Secondary considerations include DC Cold Resistance, Melting I²t values, approval agencies, and RoHS compliance status, which may vary between manufacturers while maintaining functional equivalence.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitute (Active Status, Enhanced Compliance): BK/MDL-3/8-R is the recommended substitute from Eaton - Electronics Division. This part maintains the same manufacturer lineage as the primary part while offering ROHS3 compliance and CE certification in addition to CSA and UL approvals. The part is currently active in production with 1162 pieces in stock, ensuring availability. The lower DC Cold Resistance (1.567 Ohms versus 2.35 Ohms) represents an improved electrical characteristic.

Alternative Substitutes (Active Status, Multi-Manufacturer Options): 0313.375HXP and 0313.375MXP from Littelfuse Inc. are both active production parts with ROHS3 compliance and CE certification. Both parts carry identical electrical specifications with Melting I²t of 1.23 and DC Cold Resistance of 2.095 Ohms. The 0313.375MXP has the highest inventory availability at 3666 pieces in stock.

Obsolete Part (Not Recommended for New Designs): 0034.5217 from SCHURTER Inc. is marked as obsolete and should not be selected for new designs or long-term applications, despite meeting all electrical and mechanical parameters.

Frequently Asked Questions (FAQ)

Q: Can the BK/MDQ-3/8 be directly replaced with any of the listed substitutes? A: Yes. All listed substitute parts meet the required electrical parameters (375 mA, 250 V AC, slow-blow response) and mechanical specifications (3AB/3AG package, 1/4" x 1-1/4" dimensions). Direct physical and electrical substitution is possible without circuit modification.

Q: What is the difference between BK/MDL-3/8-R and BK/MDQ-3/8? A: Both are Eaton products with identical electrical and mechanical specifications. The primary differences are: BK/MDL-3/8-R is ROHS3 compliant while BK/MDQ-3/8 is non-compliant; BK/MDL-3/8-R includes CE certification; BK/MDL-3/8-R has lower DC Cold Resistance (1.567 Ohms versus 2.35 Ohms) and a specified Melting I²t value of 0.982.

Q: Why is 0034.5217 listed if it is obsolete? A: The part is included for reference purposes in legacy system documentation and reverse-engineering applications. For new designs and production applications, active alternatives should be selected.

Q: Are the Littelfuse parts (0313.375HXP and 0313.375MXP) interchangeable with each other? A: Yes. Both parts carry identical electrical specifications, approval certifications, and mechanical dimensions. Selection between them may be based on inventory availability or supplier preference.

Q: What does ROHS3 compliance mean for fuse selection? A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements. Parts marked as ROHS3 compliant (BK/MDL-3/8-R, 0034.5217, 0313.375HXP, 0313.375MXP) are suitable for applications requiring regulatory compliance with hazardous substance restrictions. The original BK/MDQ-3/8 is non-compliant and may not be acceptable in regulated applications.

Q: Does DC Cold Resistance variation affect circuit performance? A: DC Cold Resistance values range from 1.567 Ohms to 2.35 Ohms across the substitute parts. This variation is within normal manufacturing tolerances for glass cartridge fuses and does not affect circuit protection function. Selection based on this parameter alone is not necessary for standard applications.

Q: Which substitute has the best inventory availability? A: 0313.375MXP from Littelfuse has the highest inventory with 3666 pieces in stock, followed by BK/MDL-3/8-R with 1162 pieces.