MQ 4TR Board Mount Axial Fuse Equivalent & Substitute Parts

Part Overview

The MQ 4TR is a 4A 125VAC/VDC board mount axial fuse manufactured by Bel Fuse Inc. This component is classified as obsolete, making equivalent substitute parts necessary for ongoing design support and procurement. The MQ 4TR serves as a fast-blow protection device for circuits requiring 4 ampere current limiting at 125 volts AC or DC. Substitute parts must maintain identical electrical ratings and mechanical compatibility to ensure proper circuit protection without redesign.

Substiute Parts

MQ 4TR

Bel Fuse Inc.In Stock: 916MQ 4TR Datasheet

Current PartRFQ

0251004.NRT1L

Littelfuse Inc.In Stock: 5704900251004.NRT1L Datasheet

DirectRFQ

0251004.MRT1L

Littelfuse Inc.In Stock: 34730251004.MRT1L Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the MQ 4TR is determined by strict equivalence across the following critical parameters:

• Current Rating: 4 A (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Fast Blow (exact match required)
• Mounting Type: Through Hole (exact match required)
• Fuse Type: Board Mount, Axial configuration (exact match required)
• Breaking Capacity: 50A AC, 300A DC (exact match required)
• Operating Temperature: -55°C ~ 125°C (exact match required)

The substitute parts listed below meet all these criteria. Variations in physical dimensions (diameter and length), DC cold resistance, melting I²t values, and approval certifications do not affect functional substitutability within the specified electrical and mechanical parameters.

Parameter Comparison

Engineering Selection Recommendations

Both Littelfuse PICO® II 251 series parts (0251004.NRT1L and 0251004.MRT1L) are functionally equivalent to the obsolete MQ 4TR. Selection between these two substitutes should be based on the following factors:

0251004.NRT1L is recommended for applications where REACH compliance is a regulatory requirement, as this part is REACH Affected and carries full compliance documentation. This part is available in high volume (570,431 pcs in stock) and carries expanded approval certifications including CCC, PSE, and TUV in addition to CSA and cURus.

0251004.MRT1L is suitable for applications where REACH status is not a constraint. This part carries identical electrical and mechanical specifications to 0251004.NRT1L but is listed as REACH Unaffected. Inventory availability is lower (3,400 pcs in stock) compared to the NRT1L variant.

Both parts are RoHS3 compliant and carry active product status, ensuring long-term availability and supply chain stability compared to the obsolete MQ 4TR.

Frequently Asked Questions (FAQ)

Q: Can 0251004.NRT1L and 0251004.MRT1L be used interchangeably with the MQ 4TR?

A: Yes. Both Littelfuse parts meet all critical electrical and mechanical parameters: 4A current rating, 125V AC/DC voltage rating, fast-blow response, through-hole mounting, and 50A AC / 300A DC breaking capacity. Physical dimensions differ slightly (0.110" diameter vs. 0.125" diameter for the original), but both fit standard axial fuse footprints.

Q: What is the difference between 0251004.NRT1L and 0251004.MRT1L?

A: The primary difference is REACH compliance status. 0251004.NRT1L is REACH Affected and 0251004.MRT1L is REACH Unaffected. Both parts are electrically and mechanically identical. Selection depends on regulatory requirements for your application region.

Q: Are there any thermal or performance differences between the MQ 4TR and the Littelfuse substitutes?

A: Operating temperature range is identical (-55°C ~ 125°C). Melting I²t values differ slightly (1.9 for MQ 4TR vs. 2.45 for both Littelfuse parts) and DC cold resistance differs marginally (0.023 Ohms vs. 0.0204 Ohms), but these variations do not affect functional performance within the specified electrical ratings.

Q: What certifications should I verify for my application?

A: The MQ 4TR carries CE, CSA, and cURus approvals. Both substitute parts carry CSA and cURus approvals plus additional certifications (CCC, PSE, TUV). Verify that the substitute part's certification set meets your regional and application-specific requirements.

Q: Is packaging format a consideration when selecting a substitute?

A: The MQ 4TR packaging format is not specified in the available data. Both Littelfuse substitutes are supplied in Cut Tape (CT) packaging. Confirm that cut tape format is compatible with your assembly process before procurement.