Equivalent & Substitute Parts for 5MF 8 Fuse

Part Overview

The 5MF 8 is an 8A 125VAC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc., designed for 5mm x 20mm holder applications. This part is classified as obsolete, making identification of active equivalent substitutes essential for ongoing system maintenance and new design implementations. The 5MF 8-R serves as the direct active substitute, maintaining identical electrical and mechanical specifications while offering improved compliance status.

Substiute Parts

5MF 8

Bel Fuse Inc.In Stock: 11645MF 8 Datasheet

Current PartRFQ

5MF 8-R

Bel Fuse Inc.In Stock: 25935MF 8-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

The 5MF 8-R qualifies as a direct substitute for the 5MF 8 based on the following critical parameters:

• Current Rating: 8 A (identical)
• Voltage Rating (AC): 125 V (identical)
• Fuse Type: Cartridge, Glass (identical)
• Package / Case: 5mm x 20mm (identical)
• Response Time: Fast Blow (identical)
• Breaking Capacity @ Rated Voltage: 10kA (identical)
• Melting I²t: 113 (identical)
• Operating Temperature Range: -55°C ~ 125°C (identical)

These parameters define the functional and mechanical compatibility required for direct substitution in holder-based applications.

Parameter Comparison

Engineering Selection Recommendations

The 5MF 8-R is the appropriate selection for applications currently using or specifying the 5MF 8. Both parts maintain identical electrical performance and mechanical compatibility. The 5MF 8-R offers the following advantages:

• Active product status ensures continued availability and supply chain reliability
• ROHS3 compliance meets current environmental regulations
• cULus certification provides expanded North American approval coverage
• Marginally lower DC cold resistance (0.009 Ohms vs 0.01 Ohms) represents improved electrical characteristics
• Bulk packaging availability supports production requirements

For new designs or system replacements, the 5MF 8-R should be specified to ensure long-term component availability and regulatory compliance.

Frequently Asked Questions (FAQ)

Q: Can the 5MF 8-R be used as a direct replacement for the 5MF 8?

A: Yes. Both parts share identical current rating (8A), voltage rating (125VAC), fuse type (cartridge glass), package dimensions (5mm x 20mm), response time (fast blow), breaking capacity (10kA), and melting I²t (113). They are mechanically and electrically interchangeable in holder-based applications.

Q: What is the difference in DC cold resistance between these parts?

A: The 5MF 8 has a DC cold resistance of 0.01 Ohms, while the 5MF 8-R measures 0.009 Ohms. This minor difference does not affect functional performance in standard fuse applications.

Q: Why is the 5MF 8 listed as obsolete?

A: The 5MF 8 has been discontinued by the manufacturer. The 5MF 8-R is the active equivalent and should be used for all new applications and replacements.

Q: Are there any compliance differences between these parts?

A: The 5MF 8-R is ROHS3 compliant, while the 5MF 8 is non-compliant. The 5MF 8-R also carries cULus certification in addition to CE, CSA, and PSE approvals. For applications subject to RoHS regulations, the 5MF 8-R is required.

Q: Will the 5MF 8-R fit in existing 5MF 8 holders?

A: Yes. Both parts have identical package dimensions (5mm x 20mm) and require the same holder type. Physical installation is identical.