MQ 12 Fuse Board Mount Equivalent & Substitute Parts

Part Overview

The MQ 12 is a 12 A board mount axial fuse rated for 125 V AC/DC operation, manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent substitutes necessary for ongoing system maintenance and new design implementations. The fast-blow response characteristic and through-hole mounting configuration define its primary application scope. Substitute parts must maintain electrical equivalence across current rating, response time, and mounting type while accommodating voltage rating differences within system design parameters.

Substiute Parts

MQ 12

Bel Fuse Inc.In Stock: 1260MQ 12 Datasheet

Current PartRFQ

0251012.MXL

Littelfuse Inc.In Stock: 11490251012.MXL Datasheet

DirectRFQ

0251012.NRT1L

Littelfuse Inc.In Stock: 225990251012.NRT1L Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MQ 12 is determined by strict equivalence across the following parameters:

• Current Rating: Must equal 12 A
• Response Time: Must be Fast Blow
• Mounting Type: Must be Through Hole
• Fuse Type: Must be Board Mount (Cartridge Style Excluded)
• Package / Case: Must be Axial
• Breaking Capacity: Must maintain 50A AC and 300A DC minimum
• Operating Temperature Range: Must support -55°C ~ 125°C

Voltage ratings may differ from the original 125 V AC/DC specification provided the substitute part's voltage rating is suitable for the target application circuit. Both identified substitutes (0251012.MXL and 0251012.NRT1L) are manufactured by Littelfuse Inc. under the PICO® II 251 series and meet all electrical and mechanical equivalence criteria. These parts differ only in packaging configuration (Bulk versus Cut Tape).

Parameter Comparison

Engineering Selection Recommendations

Both 0251012.MXL and 0251012.NRT1L are active production components manufactured by Littelfuse Inc. and carry CSA and cURus certifications. The primary distinction between these substitutes is packaging format: 0251012.MXL is supplied in Bulk packaging, while 0251012.NRT1L is supplied in Cut Tape (CT) format with significantly higher inventory availability (22,500 pcs versus 1,057 pcs).

Selection between these two substitutes should be based on procurement requirements and assembly process compatibility. Both parts maintain identical electrical specifications and mechanical form factors. The voltage rating reduction from 125 V to 32 V AC/DC requires circuit-level validation to confirm suitability for the target application. Both substitutes are ROHS3 compliant, providing environmental compliance advantages over the original obsolete part.

Frequently Asked Questions (FAQ)

Q: Can 0251012.MXL or 0251012.NRT1L be used as direct replacements for MQ 12?

A: Both parts meet all electrical and mechanical equivalence criteria: 12 A current rating, fast-blow response, through-hole axial mounting, and identical breaking capacity. The voltage rating difference (32 V versus 125 V) requires circuit validation. Dimensional differences (0.110" diameter versus 0.125" diameter) are minor and typically accommodate standard through-hole PCB layouts.

Q: What is the difference between 0251012.MXL and 0251012.NRT1L?

A: These parts are electrically and mechanically identical. The difference is packaging: 0251012.MXL is supplied in Bulk format, while 0251012.NRT1L is supplied in Cut Tape (CT) format. Selection depends on assembly process requirements and procurement volume.

Q: Are the substitute parts RoHS compliant?

A: Yes, both 0251012.MXL and 0251012.NRT1L are ROHS3 compliant. The original MQ 12 RoHS status was not specified.

Q: Do the substitute parts carry the same certifications as MQ 12?

A: The substitutes carry CSA and cURus certifications. The original MQ 12 also included CE certification, which is not listed for the Littelfuse alternatives. Circuit design requirements should determine if CE certification is necessary for the target application.

Q: What are the physical dimension differences?

A: MQ 12 diameter is 0.125" (3.18mm); substitute parts are 0.110" (2.80mm). Length is equivalent at 0.280" (7.10-7.11mm). The diameter reduction is minor and compatible with standard axial component PCB footprints.