5ST 125 Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The 5ST 125 is a 125 mA, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm form factor. This component requires a fuse holder for installation and is designed for circuit protection in industrial and commercial applications. The 5ST 125 is classified as obsolete, making equivalent substitute parts necessary for ongoing system maintenance and new designs. Direct replacements are available from active product lines that maintain identical electrical and mechanical specifications.

Substiute Parts

5ST 125

Bel Fuse Inc.In Stock: 8215ST 125 Datasheet

Current PartRFQ

5ST 125-R

Bel Fuse Inc.In Stock: 108415ST 125-R Datasheet

DirectRFQ

0034.3108

SCHURTER Inc.In Stock: 23590034.3108 Datasheet

DirectRFQ

0218.125HXP

Littelfuse Inc.In Stock: 18150218.125HXP Datasheet

DirectRFQ

0218.125MXBP

Littelfuse Inc.In Stock: 11050218.125MXBP Datasheet

DirectRFQ

0218.125MXP

Littelfuse Inc.In Stock: 200370218.125MXP Datasheet

DirectRFQ

0218.125TXP

Littelfuse Inc.In Stock: 12710218.125TXP Datasheet

DirectRFQ

0218.125VXP

Littelfuse Inc.In Stock: 12280218.125VXP Datasheet

DirectRFQ

0218.125MRET1P

Littelfuse Inc.In Stock: 6300218.125MRET1P Datasheet

SimilarRFQ

GDC-125MA

Eaton - Electronics DivisionIn Stock: 893GDC-125MA Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 5ST 125 is determined by strict equivalence across the following critical parameters:

• Current Rating: 125 mA (exact match required)
• Voltage Rating: 250 V AC (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 5mm x 20mm (exact match required)
• Mounting Type: Requires Holder (exact match required)
• Breaking Capacity: 35 A (exact match required)

All substitute parts listed below meet these criteria. Variations in DC cold resistance, melting I²t values, and approval agency certifications do not affect functional substitutability for the specified electrical and mechanical requirements. Parts are grouped by manufacturer and product status.

Parameter Comparison

Engineering Selection Recommendations

For new designs and ongoing maintenance applications, the 5ST 125-R from Bel Fuse Inc. is the primary recommended substitute. This part maintains identical electrical and mechanical specifications while offering active product status and ROHS3 compliance, addressing regulatory requirements for modern manufacturing.

Littelfuse 218 series parts (0218.125HXP, 0218.125MXBP, 0218.125MXP, 0218.125TXP, 0218.125VXP) provide functionally equivalent alternatives with broader approval agency certifications including UL, CSA, and K-MARK. These parts are suitable for applications requiring specific regional compliance standards.

The SCHURTER 0034.3108 (FST 5x20 series) offers an alternative from a different manufacturer with active status and ROHS3 compliance. This part is suitable for applications where multi-source qualification is required.

The Eaton GDC-125MA provides an additional alternative with active product status. Approval agency coverage is limited to cURus and IMQ certifications.

All listed substitutes are mechanically and electrically interchangeable within applications designed for the 5ST 125 specification. Selection should be based on supply chain availability, regional compliance requirements, and existing qualification documentation for the target application.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts interchangeably with the 5ST 125?

A: Yes. All listed substitute parts meet the identical electrical and mechanical specifications: 125 mA current rating, 250 V AC voltage rating, slow-blow response, 5mm x 20mm package, and 35 A breaking capacity. They are mechanically and electrically interchangeable in any application designed for the 5ST 125.

Q: What is the difference between the Littelfuse 218 series variants (HXP, MXBP, MXP, TXP, VXP)?

A: All Littelfuse 218 series variants listed maintain identical electrical and mechanical specifications for the 5ST 125 substitution. Differences in part number suffixes reflect internal Littelfuse product line designations and approval agency certifications. For the specified application parameters, they are functionally equivalent.

Q: Does the 5ST 125-R have better compliance than the original 5ST 125?

A: The 5ST 125-R is ROHS3 compliant, while the original 5ST 125 is non-compliant. For applications subject to RoHS regulations, the 5ST 125-R is the appropriate choice. Both parts are electrically and mechanically identical.

Q: Are there any mounting differences between these substitute parts?

A: All substitute parts listed require a fuse holder for installation. There are no mounting differences. The 0218.125MRET1P variant (not listed as a direct substitute) uses through-hole axial mounting and has different physical dimensions; it is not interchangeable with the 5ST 125.

Q: Which substitute part has the broadest approval agency coverage?

A: The Littelfuse 218 series parts (0218.125HXP, 0218.125MXBP, 0218.125MXP, 0218.125TXP, 0218.125VXP) carry the most comprehensive approval agency certifications, including CCC, CE, CSA, K-MARK, KC, SEMKO, UL, and VDE. Selection should align with the specific regional compliance requirements of the target application.

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

A: Yes. All substitute parts meet identical electrical and mechanical specifications and can be used together in the same application. However, for consistency in maintenance and inventory management, using a single part number across an application is recommended.