5SFP 1.25-R Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 5SFP 1.25-R is a 1.25 A, 250 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. in a 5mm x 20mm axial through-hole package. This component is active in production with 1,743 units currently in stock. Glass cartridge fuses of this specification are essential protective devices in electronic circuits requiring fast response to overcurrent conditions. Equivalent and substitute parts may be required due to supply chain considerations, regional availability, or specific certification requirements for end applications.

Substiute Parts

5SFP 1.25-R

Bel Fuse Inc.In Stock: 17595SFP 1.25-R Datasheet

Current PartRFQ

5MFP 1.25-R

Bel Fuse Inc.In Stock: 19475MFP 1.25-R Datasheet

Parametric EquivalentRFQ

0034.1517.PT

SCHURTER Inc.In Stock: 40070034.1517.PT Datasheet

DirectRFQ

02171.25MXEP

Littelfuse Inc.In Stock: 142602171.25MXEP Datasheet

DirectRFQ

BK/S500-V-1.25R

Eaton - Electronics DivisionIn Stock: 728BK/S500-V-1.25R Datasheet

DirectRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution eligibility for the 5SFP 1.25-R is determined by strict equivalence across the following critical parameters:

• Current Rating: 1.25 A (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Fast Blow (exact match required)
• Package / Case: 5mm x 20mm (Axial) (exact match required)
• Mounting Type: Through Hole (exact match required)
• Operating Temperature Range: -55°C ~ 125°C (minimum requirement)

All substitute parts listed below meet these mandatory criteria. Variations in secondary parameters such as breaking capacity, melting I²t, DC cold resistance, and dimensional tolerances are documented but do not preclude substitution when the primary electrical and mechanical specifications align.

Parameter Comparison

Engineering Selection Recommendations

All five parts listed are active products with current manufacturing status and ROHS3 or RoHS compliance. Selection among these equivalents should be based on the following factors:

Certification Coverage: The 02171.25MXEP (Littelfuse) offers the broadest approval agency coverage, including BSI, CE, CCC, CSA, KC, PSE, SEMKO, UR, and VDE. The 5SFP 1.25-R (Bel Fuse) includes CCC, CE, CSA, cULus, IMQ, SEMKO, and VDE. The BK/S500-V-1.25R (Eaton) includes BSI, CCC, CSA, cULus, IMQ, SEMKO, and VDE. The 0034.1517.PT (SCHURTER) is limited to cURus certification. The 5MFP 1.25-R (Bel Fuse) includes CE, CSA, cULus, and PSE.

Availability: The 0034.1517.PT (SCHURTER) has the highest inventory at 3,906 units. The 5MFP 1.25-R (Bel Fuse) has 1,869 units. The 5SFP 1.25-R has 1,743 units. The 02171.25MXEP (Littelfuse) has 1,326 units. The BK/S500-V-1.25R (Eaton) has the lowest inventory at 686 units.

Melting I²t Characteristics: The BK/S500-V-1.25R exhibits the fastest thermal response (0.84 I²t), while the 5SFP 1.25-R has the highest value (2.5 I²t). The 5MFP 1.25-R has the lowest value at 1.5 I²t. These variations may be significant in applications with specific thermal protection requirements.

Frequently Asked Questions (FAQ)

Q: Can the 5MFP 1.25-R be used as a direct substitute for the 5SFP 1.25-R?

A: Yes. Both parts are manufactured by Bel Fuse Inc., share identical current rating (1.25 A), voltage rating (250 V), fuse type (cartridge glass), response time (fast blow), and package dimensions (5mm x 20mm axial). The 5MFP 1.25-R has a higher breaking capacity (200 A versus 35 A) and lower melting I²t (1.5 versus 2.5), which may provide different thermal response characteristics but does not prevent substitution in applications designed for the 5SFP 1.25-R.

Q: What are the dimensional differences among these substitute parts?

A: The 5SFP 1.25-R, 5MFP 1.25-R, and BK/S500-V-1.25R have nominal dimensions of 0.217" diameter x 0.827" length (5.50mm x 21.00mm), 0.217" diameter x 0.827" length (5.50mm x 21.00mm), and 0.218" diameter x 0.831" length (5.54mm x 21.10mm) respectively. The 0034.1517.PT (SCHURTER) is 0.213" diameter x 0.886" length (5.40mm x 22.50mm). The 02171.25MXEP (Littelfuse) is 0.228" diameter x 0.886" length (5.80mm x 22.50mm). These minor variations remain within the 5mm x 20mm package classification and are compatible with standard through-hole fuse holders designed for this form factor.

Q: Which substitute part has the best certification coverage for international applications?

A: The 02171.25MXEP (Littelfuse) provides the most comprehensive certification coverage with approvals from BSI, CE, CCC, CSA, KC, PSE, SEMKO, UR, and VDE. This part is suitable for applications requiring compliance across multiple international standards and regional markets.

Q: Are there differences in DC cold resistance among these parts?

A: Yes. The 5SFP 1.25-R has the lowest DC cold resistance at 0.062 Ohms. The 02171.25MXEP (Littelfuse) is 0.0701 Ohms. The 5MFP 1.25-R is 0.09 Ohms. The BK/S500-V-1.25R is 0.096 Ohms. The 0034.1517.PT does not specify this parameter. These differences are minor and do not affect substitution compatibility in standard circuit protection applications.

Q: Which part should be selected for maximum inventory availability?

A: The 0034.1517.PT (SCHURTER Inc.) has the highest current inventory at 3,906 units in stock, followed by the 5MFP 1.25-R (Bel Fuse) at 1,869 units.