5MFP 8 Equivalent & Substitute Parts

Part Overview

The 5MFP 8 is an 8A 125VAC fast-blow glass cartridge fuse with a 5mm x 20mm axial form factor, manufactured by Bel Fuse Inc. This component is classified as obsolete, making identification of suitable alternatives necessary for ongoing system maintenance and component procurement. The part features a 10kA breaking capacity and operates across a temperature range of -55°C to 125°C. Due to its obsolete status, the active equivalent 5MFP 8-R provides a direct functional replacement while maintaining full electrical and mechanical compatibility.

Substiute Parts

5MFP 8

Bel Fuse Inc.In Stock: 8865MFP 8 Datasheet

Current PartRFQ

5MFP 8-R

Bel Fuse Inc.In Stock: 18315MFP 8-R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

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

• Current Rating: Both parts are rated at 8 A
• Voltage Rating: Both parts are rated at 125 V AC
• Fuse Type: Both are fast-blow glass cartridge fuses
• Physical Form Factor: Both use the 5mm x 20mm axial package
• Breaking Capacity: Both provide 10kA breaking capacity at rated voltage
• Melting I²t: Both have identical melting I²t values of 113
• Operating Temperature: Both operate across -55°C to 125°C
• Mounting Configuration: Both are through-hole mounted components

The substitution is based on electrical equivalence and mechanical interchangeability. The 5MFP 8-R maintains all functional characteristics required for direct replacement in existing circuit designs.

Parameter Comparison

Engineering Selection Recommendations

The 5MFP 8-R is the appropriate selection for applications currently using the 5MFP 8. The substitute part maintains electrical equivalence across all critical parameters: current rating, voltage rating, breaking capacity, and thermal characteristics.

The 5MFP 8-R offers the advantage of active product status, ensuring ongoing availability and supply chain continuity. The part achieves ROHS3 compliance, meeting modern environmental and regulatory requirements. DC cold resistance is marginally lower (0.0092 Ohms versus 0.01 Ohms), which represents an improvement in electrical performance.

Approval certifications for the 5MFP 8-R include CE, CSA, and PSE standards. The original 5MFP 8 included UL certification; verification of UL certification requirements for the application should be performed if UL compliance is mandatory.

Frequently Asked Questions (FAQ)

Q: Can the 5MFP 8-R be used as a direct replacement for the 5MFP 8 in existing designs?

A: Yes. The 5MFP 8-R is electrically and mechanically equivalent to the 5MFP 8. Both parts share identical current ratings (8 A), voltage ratings (125 V AC), fuse type (fast-blow glass cartridge), physical dimensions (5mm x 20mm axial), and breaking capacity (10kA). Through-hole mounting is identical for both parts.

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

A: The 5MFP 8-R has a DC cold resistance of 0.0092 Ohms compared to 0.01 Ohms for the 5MFP 8. This represents a marginal improvement and does not affect functional compatibility or circuit performance.

Q: Are there compliance differences between the 5MFP 8 and 5MFP 8-R?

A: The 5MFP 8-R achieves ROHS3 compliance, while the 5MFP 8 is RoHS non-compliant. The 5MFP 8-R holds CE, CSA, and PSE certifications. The original 5MFP 8 included UL certification in addition to CE, CSA, and PSE. If UL certification is required for your application, confirm UL status for the 5MFP 8-R with the manufacturer or authorized distributor.

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

A: The 5MFP 8 has reached end-of-life status. The 5MFP 8-R is the active equivalent and is recommended for all new designs and ongoing procurement.

Q: Are the physical dimensions identical?

A: Yes. Both parts measure 0.217" diameter x 0.827" length (5.50mm x 21.00mm). They are mechanically interchangeable in through-hole mounting applications.

Q: What is the melting I²t specification, and is it the same for both parts?

A: Melting I²t is 113 for both the 5MFP 8 and 5MFP 8-R. This parameter defines the thermal energy required to melt the fuse element and is identical across both parts.