3SBP 4 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 3SBP 4 is a 4 A, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Bel Fuse Inc. in the 3AB/3AG form factor (1/4" x 1-1/4" axial). This part is classified as obsolete. Identifying equivalent and substitute parts is necessary to maintain circuit protection functionality in legacy equipment and to access active inventory from alternative manufacturers.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole
Breaking Capacity @ Rated Voltage	200 A
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.272" - 0.275" Dia x 1.275" - 1.280" L

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters:

Current Rating: 4 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Slow Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Mounting Type: Through Hole (exact match required)
Breaking Capacity @ Rated Voltage: 200 A (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)

All substitute parts listed meet these criteria. Dimensional tolerances (0.272" - 0.275" diameter and 1.275" - 1.280" length) fall within acceptable mechanical compatibility for the 3AB/3AG form factor.

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Breaking Capacity (A)	DC Cold Resistance (Ohms)	Product Status	RoHS Status	Approval Agencies
3SBP 4	Bel Fuse Inc.	4	250	Slow Blow	200	0.05	Obsolete	Non-compliant	CE, CSA, PSE, UL
3SBP 4-R	Bel Fuse Inc.	4	250	Slow Blow	200	0.04	Obsolete	ROHS3 Compliant	CE, CSA, cULus, PSE
0315004.HXP	Littelfuse Inc.	4	250	Slow Blow	200	0.0311	Active	ROHS3 Compliant	CE, CSA, K-MARK, PSE, UL
0315004.MXP	Littelfuse Inc.	4	250	Slow Blow	200	0.0311	Active	ROHS3 Compliant	CE, CSA, K-MARK, PSE, UL
0315004.VXP	Littelfuse Inc.	4	250	Slow Blow	200	0.0311	Active	ROHS3 Compliant	CE, CSA, KC, PSE, UL
0315004.MXF31P	Littelfuse Inc.	4	250	Slow Blow	200	0.0311	Active	ROHS3 Compliant	CE, CSA, KC, PSE, UL

Engineering Selection Recommendations

Direct Substitutes (Bel Fuse Inc. Series): The 3SBP 4-R is a direct manufacturer equivalent from Bel Fuse Inc. with identical electrical specifications. It offers improved RoHS3 compliance and lower DC cold resistance (0.04 Ohms vs. 0.05 Ohms). Approval agencies include cULus certification. This part is preferred for applications requiring Bel Fuse brand continuity within the same product line.

Active Alternatives (Littelfuse Inc. Series 315): The 0315004.HXP, 0315004.MXP, 0315004.VXP, and 0315004.MXF31P are active production parts from Littelfuse Inc. All meet identical electrical and mechanical specifications. These parts feature RoHS3 compliance, lower DC cold resistance (0.0311 Ohms), and broader approval agency coverage including K-MARK and KC certifications. These alternatives are recommended for new designs and long-term supply continuity, as they are in active production status.

Compliance Considerations: The original 3SBP 4 is RoHS non-compliant. All substitute parts listed are ROHS3 compliant, making them suitable for applications subject to RoHS regulations. All parts maintain CE, CSA, and PSE certifications. Littelfuse alternatives add K-MARK and KC approvals, expanding regulatory coverage.

Frequently Asked Questions (FAQ)

Q: Can I use a Littelfuse 0315004.HXP as a direct replacement for the obsolete 3SBP 4? A: Yes. The 0315004.HXP meets all electrical and mechanical specifications: 4 A, 250 V AC, slow-blow response, 200 A breaking capacity, and 3AB/3AG form factor. Dimensional tolerances are compatible. The part is in active production.

Q: What is the difference between 0315004.HXP, 0315004.MXP, and 0315004.VXP? A: All three parts are electrically and mechanically identical. The differences lie in approval agency coverage: 0315004.HXP includes K-MARK; 0315004.MXP includes K-MARK; 0315004.VXP includes KC. Select based on required regulatory certifications for your application region.

Q: Why does the 3SBP 4-R have lower DC cold resistance than the original 3SBP 4? A: DC cold resistance values (0.04 Ohms vs. 0.05 Ohms) are within normal manufacturing tolerance ranges for this fuse category and do not affect functional equivalence. Both values are acceptable for circuit protection applications.

Q: Is the 0315004.MXF31P interchangeable with the other Littelfuse alternatives? A: Yes. The 0315004.MXF31P is electrically and mechanically equivalent to 0315004.HXP, 0315004.MXP, and 0315004.VXP. All share identical current rating, voltage rating, response time, breaking capacity, and form factor.

Q: Can I use these substitutes in legacy equipment designed for the 3SBP 4? A: Yes, provided the equipment uses standard 3AB/3AG fuse holders. All substitute parts are mechanically compatible with this form factor. Verify that your fuse holder accommodates the dimensional tolerances specified (0.272" - 0.275" diameter, 1.275" - 1.280" length).

Q: Which substitute part should I choose for new designs? A: For new designs, select from the active Littelfuse alternatives (0315004.HXP, 0315004.MXP, 0315004.VXP, or 0315004.MXF31P). These parts offer RoHS3 compliance, active production status, and broader regulatory certifications. Choose the variant that matches your required approval agencies.

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