BK/MDQ-1/4 Equivalent & Substitute Parts

Part Overview

The BK/MDQ-1/4 is a 250 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 1037 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 from different manufacturers with equivalent electrical and mechanical specifications.

Substiute Parts

BK/MDQ-1/4

Eaton - Electronics DivisionIn Stock: 1068BK/MDQ-1/4 Datasheet

Current PartRFQ

BK/MDL-1/4-R

Eaton - Electronics DivisionIn Stock: 1629BK/MDL-1/4-R Datasheet

Parametric EquivalentRFQ

MDQ-1/4

Eaton - Electronics DivisionIn Stock: 1149MDQ-1/4 Datasheet

Parametric EquivalentRFQ

0034.3411

SCHURTER Inc.In Stock: 9940034.3411 Datasheet

Parametric EquivalentRFQ

0313.250HXP

Littelfuse Inc.In Stock: 8940313.250HXP Datasheet

Parametric EquivalentRFQ

0313.250MXP

Littelfuse Inc.In Stock: 16490313.250MXP Datasheet

Parametric EquivalentRFQ

0313.250VXP

Littelfuse Inc.In Stock: 11710313.250VXP Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the BK/MDQ-1/4 is determined by strict equivalence across the following parameters:

• Current Rating: 250 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Response Time: Slow Blow (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (exact match required)
• Size / Dimension: 0.250" Dia x 1.250" L / 6.35mm x 31.75mm (exact match required)
• Breaking Capacity @ Rated Voltage: 35A (exact match required)

All substitute parts listed below meet these criteria. Secondary parameters such as DC Cold Resistance, Melting I²t, and compliance certifications are provided for engineering reference but do not disqualify substitution when primary parameters are equivalent.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes (Active Status, Full Compliance):

BK/MDL-1/4-R and MDQ-1/4 are direct substitutes from Eaton - Electronics Division. BK/MDL-1/4-R offers the advantage of ROHS3 compliance and CE certification in addition to CSA and UL approvals. MDQ-1/4 maintains identical electrical characteristics to the main part with CSA and UL certifications.

Alternative Manufacturer Substitutes (Active Status):

0313.250HXP, 0313.250MXP, and 0313.250VXP are manufactured by Littelfuse Inc. and are all active products with ROHS3 compliance and CE, CSA, and UL certifications. These parts are electrically equivalent with identical current, voltage, and response time ratings. All three Littelfuse parts feature identical DC Cold Resistance (4.27 Ohms) and Melting I²t (0.385), differing only in internal design designation.

Obsolete Status Consideration:

0034.3411 from SCHURTER Inc. is marked as obsolete. While electrically equivalent, this part should be selected only when existing inventory must be maintained or when legacy system compatibility is required. New designs should avoid this part number.

Compliance Considerations:

The main part BK/MDQ-1/4 is RoHS non-compliant. For applications requiring RoHS3 compliance, BK/MDL-1/4-R, 0034.3411, 0313.250HXP, 0313.250MXP, and 0313.250VXP are all compliant alternatives. For applications requiring CE certification, BK/MDL-1/4-R and all Littelfuse parts (0313 series) provide this certification.

Frequently Asked Questions (FAQ)

Q: Can I substitute BK/MDQ-1/4 with any of the listed parts?

A: Yes. All listed parts meet the core electrical and mechanical requirements: 250 mA current rating, 250 V AC voltage rating, slow-blow response time, glass cartridge type, 3AB/3AG package, and 1/4" x 1-1/4" dimensions. Physical installation in existing holders is compatible.

Q: What is the difference between BK/MDL-1/4-R and MDQ-1/4?

A: Both are Eaton products with identical electrical ratings. BK/MDL-1/4-R includes ROHS3 compliance and CE certification, while MDQ-1/4 does not list ROHS3 status. BK/MDL-1/4-R has lower DC Cold Resistance (3.208 Ohms vs. 5.775 Ohms) and includes Melting I²t specification (0.447).

Q: Why are there three Littelfuse part numbers (0313.250HXP, 0313.250MXP, 0313.250VXP)?

A: All three Littelfuse parts are electrically and mechanically identical with the same current, voltage, response time, and dimensions. The suffix designations (HXP, MXP, VXP) represent internal design variants within the Littelfuse 313 series. Selection among these three is interchangeable for the stated application.

Q: Should I use the SCHURTER 0034.3411 part?

A: The 0034.3411 is electrically equivalent but marked as obsolete. Use this part only for maintaining existing inventory or supporting legacy equipment. For new designs or restocking, select from active products: BK/MDL-1/4-R, MDQ-1/4, or the Littelfuse 0313 series.

Q: What compliance certifications are required for my application?

A: The main part BK/MDQ-1/4 carries CSA and UL certifications but is RoHS non-compliant. If RoHS3 compliance is required, use BK/MDL-1/4-R, 0034.3411, 0313.250HXP, 0313.250MXP, or 0313.250VXP. If CE certification is required, use BK/MDL-1/4-R or any Littelfuse part (0313 series).

Q: Are there any resistance or thermal differences I should consider?

A: DC Cold Resistance varies among substitutes: BK/MDQ-1/4 and MDQ-1/4 are 5.775 Ohms, BK/MDL-1/4-R is 3.208 Ohms, and all Littelfuse parts are 4.27 Ohms. Melting I²t values are provided for BK/MDL-1/4-R (0.447), SCHURTER (0.4), and Littelfuse parts (0.385). These differences are within the slow-blow fuse category and do not affect substitution validity for the stated electrical ratings.

Q: Can I mix different substitute parts in the same circuit or equipment?

A: Yes. All substitute parts are electrically and mechanically equivalent. However, for consistency in maintenance and inventory management, standardizing on a single part number per application is recommended.