MQ 1 Equivalent & Substitute Parts

Part Overview

The MQ 1 is a board mount axial fuse manufactured by Bel Fuse Inc., rated for 1 A at 125 V AC/DC with fast blow response characteristics. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support, maintenance, and production continuity. Substitute parts must maintain identical electrical ratings, mechanical compatibility, and approval certifications to ensure direct interchangeability in existing circuit designs.

Substiute Parts

MQ 1

Bel Fuse Inc.In Stock: 1145MQ 1 Datasheet

Current PartRFQ

0251001.MXL

LittelfuseIn Stock: 12600251001.MXL Datasheet

DirectRFQ

0251001.NRT1L

Littelfuse Inc.In Stock: 2020420251001.NRT1L Datasheet

DirectRFQ

7010.7070.13

SCHURTER Inc.In Stock: 8037010.7070.13 Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MQ 1 is determined by strict equivalence across the following parameters: current rating (1 A), voltage ratings (125 V AC and 125 V DC), response time (fast blow), mounting type (through hole), and fuse type (board mount, cartridge style excluded). All substitute parts must maintain these electrical and mechanical specifications to ensure functional compatibility within the original circuit design.

The identified substitute parts are grouped as follows:

Group 1: Direct Electrical & Mechanical Equivalents (Littelfuse PICO® II 251 Series)

• 0251001.MXL (Bulk packaging)
• 0251001.NRT1L (Cut Tape packaging)

These parts maintain identical current and voltage ratings, fast blow response, through hole mounting, and axial package configuration. Both are active products with enhanced approval certifications.

Group 2: Functional Equivalent with Package Variation (SCHURTER Inc.)

• 7010.7070.13 (Cartridge, Non-Standard Axial)

This part meets all electrical requirements but uses a non-standard cartridge axial package rather than standard axial, requiring mechanical verification for PCB footprint compatibility.

Parameter Comparison

Engineering Selection Recommendations

Primary Substitutes: Littelfuse 0251001.MXL and 0251001.NRT1L

Both Littelfuse PICO® II 251 series parts are recommended as primary substitutes for the obsolete MQ 1. These parts maintain full electrical equivalence with identical current ratings, voltage ratings, and breaking capacity specifications. Both are active products with expanded approval certifications (CCC, CSA, cURus, PSE, TUV) compared to the original part, and both comply with ROHS3 standards. Selection between these two depends on packaging requirements: 0251001.MXL is supplied in bulk packaging, while 0251001.NRT1L is supplied in cut tape format for automated assembly processes.

Secondary Substitute: SCHURTER 7010.7070.13

The SCHURTER part meets all electrical requirements but operates within a reduced temperature range (-55°C ~ 85°C versus -55°C ~ 125°C) and uses a non-standard cartridge axial package. This part is suitable only when the reduced upper operating temperature is acceptable and PCB footprint compatibility with the non-standard package geometry can be confirmed. The SCHURTER part carries CSA and UR certifications.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 0251001.MXL and 0251001.NRT1L be used interchangeably with the MQ 1?

A: Yes. Both Littelfuse parts maintain identical electrical specifications (1 A, 125 V AC/DC, fast blow, 50 A AC / 300 A DC breaking capacity) and through hole axial mounting. The difference between these two is packaging format only: bulk versus cut tape. Both are direct electrical and mechanical equivalents.

Q: What is the difference between the Littelfuse and SCHURTER substitutes?

A: The Littelfuse parts (0251001.MXL and 0251001.NRT1L) are standard axial packages with identical dimensions to the original MQ 1 specification. The SCHURTER 7010.7070.13 uses a non-standard cartridge axial package with different physical dimensions (0.093" Dia x 0.315" L versus 0.110" Dia x 0.280" L) and a reduced operating temperature range (-55°C ~ 85°C). PCB footprint compatibility must be verified before selecting the SCHURTER part.

Q: Are there compliance or certification differences between the substitute parts?

A: The Littelfuse parts carry expanded certifications (CCC, CSA, cURus, PSE, TUV) and ROHS3 compliance compared to the original MQ 1. The SCHURTER part carries CSA and UR certifications. All three parts are REACH unaffected and classified as EAR99 for export control purposes.

Q: Does the difference in DC cold resistance between the MQ 1 and Littelfuse substitutes affect circuit performance?

A: The DC cold resistance of the Littelfuse parts (0.128 Ohms) is slightly higher than the MQ 1 (0.11 Ohms). This difference is within typical tolerance ranges for fuse components and does not affect circuit protection function. Circuit designs should be evaluated to confirm this resistance variance is acceptable for the specific application.

Q: What packaging options are available for production?

A: Littelfuse 0251001.MXL is supplied in bulk packaging for manual assembly or reel-based processes. Littelfuse 0251001.NRT1L is supplied in cut tape format, suitable for automated pick-and-place assembly equipment. Both formats maintain identical electrical and mechanical specifications.