5MF 2 Glass Cartridge Fuse 2A 250VAC 5x20mm Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. 5MF 2 is a 2A 250VAC fast-blow glass cartridge fuse in 5x20mm form factor, designed for circuit protection in AC/DC applications. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance and new designs. The 5MF 2 requires a dedicated fuse holder for installation and operates across a temperature range of -55°C to 125°C. Direct replacements and parametric equivalents are available from multiple manufacturers with active product status.

Key Parameters

Parameter	5MF 2
Current Rating	2 A
Voltage Rating (AC)	250 V
Response Time	Fast Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	200A
Melting I²t	4.4
Operating Temperature Range	-55°C ~ 125°C
DC Cold Resistance	0.05 Ohms
Product Status	Obsolete

Substitute Part Grouping Explanation

Substitution for the 5MF 2 is determined by strict equivalence across the following critical parameters: current rating (2A), AC voltage rating (250V), response time (fast blow), and physical package (5x20mm). All substitute parts must maintain the same fuse type (cartridge, glass) and mounting requirement (requires holder).

Substitute parts are grouped into two categories:

Direct Manufacturer Equivalents maintain identical electrical characteristics and are sourced from the original manufacturer (Bel Fuse Inc.) with active product status. These parts differ only in packaging format or resistance specifications within acceptable tolerances.

Parametric Equivalents and Similar Parts from alternative manufacturers (Littelfuse Inc., SCHURTER Inc., Eaton) meet the core electrical requirements but may vary in breaking capacity, melting I²t, approval agencies, or operating temperature ranges. These parts are suitable for applications where the primary function—circuit protection at 2A 250VAC—is the determining factor.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage AC (V)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
5MF 2	Bel Fuse Inc.	2	250	Fast Blow	5x20mm	200	4.4	0.05	Obsolete	Non-compliant
5MF 2-R	Bel Fuse Inc.	2	250	Fast Blow	5x20mm	200	4.4	0.046	Active	ROHS3 Compliant
5SF 2-R	Bel Fuse Inc.	2	250	Fast Blow	5x20mm	35	6.4	0.036	Active	ROHS3 Compliant
0034.3877	SCHURTER Inc.	2	250	Fast Blow	5x20mm	100	2.93	—	Active	ROHS3 Compliant
0034.1519	SCHURTER Inc.	2	250	Fast Blow	5x20mm	35	5.28	—	Active	ROHS3 Compliant
0217002.HXP	Littelfuse Inc.	2	250	Fast Blow	5x20mm	35	5.73	0.0416	Active	ROHS3 Compliant
0217002.MXP	Littelfuse Inc.	2	250	Fast Blow	5x20mm	35	5.73	0.0416	Active	ROHS3 Compliant
0235002.HXP	Littelfuse Inc.	2	250	Fast Blow	5x20mm	100	2.645	0.0603	Active	ROHS3 Compliant
BK1/S500-2-R	Eaton - Electronics Division	2	250	Fast Blow	5x20mm	35	4.2	0.043	Active	ROHS3 Compliant
GDB-2A	Eaton - Electronics Division	2	250	Fast Blow	5x20mm	35	4.2	0.043	Active	RoHS Compliant

Engineering Selection Recommendations

Primary Recommendation: 5MF 2-R (Bel Fuse Inc.)

The 5MF 2-R is the direct successor to the obsolete 5MF 2, maintaining identical electrical performance with 200A breaking capacity and 4.4 melting I²t. This part carries active product status and ROHS3 compliance, making it the preferred choice for direct replacement in existing designs. Bulk packaging availability (11,150 pcs in stock) ensures supply continuity.

Secondary Recommendation: 5SF 2-R (Bel Fuse Inc.)

The 5SF 2-R provides parametric equivalence with identical current and voltage ratings. It features lower DC cold resistance (0.036 Ohms) and higher melting I²t (6.4), offering enhanced thermal performance. Breaking capacity is reduced to 35A, which remains suitable for most 2A 250VAC applications. ROHS3 compliance and active status support long-term availability.

Alternative Options: Littelfuse 217 and 235 Series

The Littelfuse 0217002.HXP, 0217002.MXP, and 0235002.HXP maintain full electrical equivalence at 2A 250VAC with fast-blow response. These parts carry comprehensive international approvals (BSI, CE, CCC, CSA, KC, PSE, SEMKO, UR, VDE) and ROHS3 compliance. The 235 series offers 100A breaking capacity comparable to the original 5MF 2.

Alternative Options: SCHURTER FSK and FSF Series

SCHURTER 0034.3877 (FSK 5x20) and 0034.1519 (FSF 5x20) provide parametric equivalence with 2A 250VAC ratings and fast-blow response. Operating temperature range for the FSK series is -40°C to 85°C, which is narrower than the original -55°C to 125°C specification. These parts are suitable for applications within the reduced temperature envelope.

Alternative Options: Eaton S500 and GDB Series

Eaton BK1/S500-2-R and GDB-2A maintain 2A 250VAC specifications with 35A breaking capacity and 4.2 melting I²t. Both carry ROHS3 compliance and active product status. The S500 series includes comprehensive international approvals (BSI, CCC, cURus, IMQ, PSE, SEMKO, VDE).

Not Recommended: BP/GMA-2A (Eaton - Bussmann)

The BP/GMA-2A operates at 125VAC, not 250VAC, and is not suitable for 250VAC applications despite matching current rating and package size.

Frequently Asked Questions (FAQ)

Q: Can I use 5SF 2-R as a direct replacement for 5MF 2?

A: Yes. The 5SF 2-R meets all core electrical requirements: 2A current rating, 250VAC voltage rating, fast-blow response, and 5x20mm package. It requires the same holder type and operates across the same temperature range (-55°C to 125°C). The lower DC cold resistance and higher melting I²t represent improved thermal characteristics.

Q: What is the difference between breaking capacity ratings (200A vs. 35A vs. 100A)?

A: Breaking capacity indicates the maximum fault current the fuse can safely interrupt without rupturing the fuse element or holder. The original 5MF 2 specifies 200A breaking capacity. Substitute parts with lower breaking capacity (35A or 100A) remain suitable for 2A 250VAC circuits where fault currents do not exceed their rated breaking capacity. System design must verify that available fault current does not exceed the substitute part's breaking capacity.

Q: Are all substitute parts RoHS compliant?

A: Most substitute parts carry ROHS3 compliance. The original 5MF 2 is RoHS non-compliant. If RoHS compliance is required for your application, select from 5MF 2-R, 5SF 2-R, SCHURTER 0034.3877, SCHURTER 0034.1519, Littelfuse 0217002.HXP, 0217002.MXP, 0235002.HXP, or Eaton BK1/S500-2-R.

Q: Can I use parts from different manufacturers interchangeably?

A: Yes, provided they meet the core electrical specifications: 2A current rating, 250VAC voltage rating, fast-blow response, and 5x20mm package. All listed substitute parts satisfy these criteria. However, verify that approval agencies and certifications match your application requirements.

Q: What does melting I²t represent?

A: Melting I²t is a thermal characteristic that describes the fuse element's energy absorption capacity before melting. Higher I²t values indicate greater thermal mass and slower response to overcurrent. The original 5MF 2 specifies 4.4 I²t. Substitute parts range from 2.645 to 6.4 I²t. Select based on your circuit's inrush current characteristics and desired response time.

Q: Why is the operating temperature range important?

A: The original 5MF 2 operates from -55°C to 125°C. Most substitute parts maintain this range. SCHURTER 0034.3877 (FSK series) operates only from -40°C to 85°C. If your application requires operation below -40°C or above 85°C, avoid the FSK series.

Q: What is DC cold resistance and why does it vary?

A: DC cold resistance is the electrical resistance of the fuse element at room temperature. It ranges from 0.036 to 0.0603 Ohms across substitute parts. Lower resistance reduces voltage drop across the fuse during normal operation, minimizing heat generation. This parameter is provided for circuit analysis but does not affect substitutability for 2A 250VAC protection.

Q: Can I substitute the 5MF 2 with BP/GMA-2A?

A: No. The BP/GMA-2A operates at 125VAC, not 250VAC. Using a 125VAC fuse in a 250VAC circuit creates a safety hazard and violates electrical standards.

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