5MT 250-R Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The 5MT 250-R is a 250 mA, 250 V AC/DC glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm form factor with medium blow response time. This part is classified as obsolete, making equivalent substitutes necessary for ongoing system maintenance and new designs. The fuse requires a compatible holder for installation and is approved by CE, CSA, and cULus agencies.

Substiute Parts

5MT 250-R

Bel Fuse Inc.In Stock: 9185MT 250-R Datasheet

Current PartRFQ

20102500001

Littelfuse Inc.In Stock: 72320102500001 Datasheet

SimilarRFQ

20102500021

Littelfuse Inc.In Stock: 105120102500021 Datasheet

SimilarRFQ

BK/GMC-250-R

Eaton - Electronics DivisionIn Stock: 1211BK/GMC-250-R Datasheet

SimilarRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 5MT 250-R is determined by the following mandatory parameters:

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

All identified substitute parts meet these core electrical and mechanical criteria. Variations in breaking capacity, melting I²t, operating temperature range, and DC cold resistance do not preclude substitution when the primary parameters align.

Parameter Comparison

Engineering Selection Recommendations

All three substitute parts are functionally equivalent to the 5MT 250-R based on core electrical and mechanical parameters. Selection should be based on the following factors:

Littelfuse 20102500001 and 20102500021: Both parts are active products with higher breaking capacity (80A) and lower melting I²t (0.13) compared to the original. These parts carry cULus approval and are suitable for applications where enhanced breaking capacity is acceptable. Operating temperature range is -25°C to 70°C.

Eaton BK/GMC-250-R: This part maintains the same breaking capacity (35A) as the original 5MT 250-R and carries CSA, KC-MARK, and UL approvals. The melting I²t is significantly lower (0.046), which may be relevant for applications with specific thermal response requirements. Operating temperature is not specified in the provided data.

All substitute parts are ROHS3 compliant and REACH unaffected, matching the environmental compliance profile of the original part.

Frequently Asked Questions (FAQ)

Q: Can the Littelfuse 20102500001 or 20102500021 be used as direct replacements for the 5MT 250-R?

A: Yes. Both parts match the mandatory substitution parameters: 250 mA current rating, 250 V AC voltage rating, glass cartridge fuse type, 5mm x 20mm package, medium blow response, and holder-based mounting. The higher breaking capacity (80A vs. 35A) and lower melting I²t do not prevent substitution when these parameters are acceptable for the application.

Q: What is the difference between Littelfuse 20102500001 and 20102500021?

A: Both parts are electrically and mechanically identical. The primary difference is inventory availability: 20102500001 has 698 pieces in stock, while 20102500021 has 974 pieces in stock.

Q: How does the Eaton BK/GMC-250-R differ from the Littelfuse options?

A: The Eaton part maintains the same breaking capacity (35A) as the original 5MT 250-R but has a significantly lower melting I²t (0.046 vs. 0.13 for Littelfuse). This indicates faster thermal response. Approval agencies differ: Eaton carries CSA, KC-MARK, and UL certifications, while Littelfuse carries cULus certification.

Q: Are all substitute parts physically compatible with existing 5MT 250-R holders?

A: All substitute parts use the same 5mm x 20mm form factor and require a compatible holder for installation, matching the original part's mounting requirements.

Q: What is the significance of the operating temperature range differences?

A: The 5MT 250-R operates from -55°C to 125°C, while Littelfuse substitutes operate from -25°C to 70°C. For applications requiring operation outside the -25°C to 70°C range, the Eaton BK/GMC-250-R may be preferable, though its operating temperature is not specified in the provided data.

Q: Are all substitute parts RoHS compliant?

A: Yes. All substitute parts are ROHS3 compliant and REACH unaffected, matching the environmental compliance of the original 5MT 250-R.