5STP 125 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 5STP 125 is a 125 mA, 250 V AC/DC glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm axial through-hole package with slow-blow response characteristics. The main part (5STP 125) carries obsolete product status, making identification of active equivalent and substitute parts essential for ongoing design support and procurement. Direct replacements and functionally equivalent alternatives are available from multiple manufacturers with active product status.

Substiute Parts

5STP 125

Bel Fuse Inc.In Stock: 9115STP 125 Datasheet

Current PartRFQ

5STP 125-R

Bel Fuse Inc.In Stock: 17935STP 125-R Datasheet

DirectRFQ

0034.3108.PT

SCHURTER Inc.In Stock: 13140034.3108.PT Datasheet

DirectRFQ

0218.125MRET1P

Littelfuse Inc.In Stock: 6300218.125MRET1P Datasheet

SimilarRFQ

0218.125MXEP

Littelfuse Inc.In Stock: 11590218.125MXEP Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters: current rating (125 mA), voltage rating (250 V AC), fuse type (cartridge glass), package dimensions (5mm x 20mm axial), response time (slow blow), and mounting configuration (through hole). All listed substitute parts meet these core electrical and mechanical requirements.

The substitute parts are categorized as follows:

Direct Manufacturer Equivalents: Parts that maintain identical electrical specifications and package form factor with active product status, differing only in packaging configuration or manufacturer designation.

Similar Functional Equivalents: Parts that satisfy all core electrical and mechanical parameters but may exhibit minor variations in physical dimensions, melting I²t characteristics, or DC cold resistance within acceptable tolerance ranges for the application category.

Parameter Comparison

Engineering Selection Recommendations

5STP 125-R (Bel Fuse Inc.): This part represents the direct active equivalent to the obsolete 5STP 125. It maintains identical electrical specifications, package dimensions, and DC cold resistance. The part carries ROHS3 compliance and active product status. Selection of this part eliminates obsolescence risk while preserving all electrical and mechanical characteristics of the original design.

0034.3108.PT (SCHURTER Inc.): This part satisfies all core electrical and mechanical requirements with active product status and ROHS3 compliance. The melting I²t value (0.064) is slightly elevated compared to the main part (0.05), and physical dimensions show minor variation (5.40mm diameter vs. 5.50mm, 22.50mm length vs. 21.00mm). These variations remain within acceptable tolerance for the 5mm x 20mm cartridge fuse category. Approval certifications include cURus.

0218.125MRET1P (Littelfuse Inc.): This part meets all core electrical specifications with active product status and ROHS3 compliance. Physical dimensions show measurable variation (5.80mm diameter, 22.50mm length) and melting I²t is significantly higher (0.1465 vs. 0.05). DC cold resistance is lower (4.2 Ohms vs. 6.8 Ohms). Approval certifications include CCC, CE, CSA, KC, SEMKO, UL, and VDE. Packaging is supplied as Tape & Reel.

0218.125MXEP (Littelfuse Inc.): This part satisfies all core electrical and mechanical requirements with active product status and ROHS3 compliance. Physical dimensions and electrical characteristics are identical to 0218.125MRET1P. Approval certifications include CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. Packaging is supplied in bulk configuration.

Frequently Asked Questions (FAQ)

Q: Can 5STP 125-R be used as a direct replacement for the obsolete 5STP 125?

A: Yes. The 5STP 125-R maintains identical current rating (125 mA), voltage rating (250 V AC), fuse type (cartridge glass), package dimensions (5mm x 20mm), response time (slow blow), and DC cold resistance (6.8 Ohms). It is the recommended replacement for obsolete designs.

Q: What is the significance of the melting I²t variation between substitute parts?

A: Melting I²t defines the thermal energy required to melt the fuse element. The 5STP 125 and 5STP 125-R both specify 0.05, while SCHURTER 0034.3108.PT specifies 0.064, and Littelfuse parts specify 0.1465. Higher I²t values indicate slower thermal response. Selection must align with the circuit protection requirements of the original design.

Q: Are there packaging differences between substitute parts?

A: Yes. The 5STP 125-R, 0034.3108.PT, and 0218.125MXEP are supplied in bulk packaging. The 0218.125MRET1P is supplied in Tape & Reel (TR) configuration. Packaging selection depends on assembly process requirements and procurement volume.

Q: Do all substitute parts meet the same regulatory certifications as the original 5STP 125?

A: No. The original 5STP 125 carries CE, CSA, IMQ, SEMKO, UL, and VDE certifications. The 5STP 125-R adds CCC and cULus certifications. SCHURTER 0034.3108.PT carries only cURus certification. Littelfuse parts carry CCC, CE, CSA, SEMKO, UL, and VDE certifications (with K-MARK or KC variants). Certification requirements for the target application must be verified before selection.

Q: What is the difference between ROHS3 compliance and the non-compliant status of the original part?

A: ROHS3 compliance indicates conformance to the Restriction of Hazardous Substances Directive 3, restricting specific hazardous materials in electrical and electronic equipment. All active substitute parts listed carry ROHS3 compliance, while the obsolete 5STP 125 does not. New designs should specify ROHS3-compliant alternatives.

Q: Can Littelfuse 0218.125MXEP and 0218.125MRET1P be used interchangeably?

A: These parts are electrically and mechanically identical. The primary difference is packaging: 0218.125MXEP is supplied in bulk, while 0218.125MRET1P is supplied in Tape & Reel. Selection depends on assembly process and procurement requirements, not electrical performance.