3SB 4 Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The 3SB 4 is a 4 A, 250 V AC/DC slow-blow glass cartridge fuse manufactured by Bel Fuse Inc. in the 3SB series. This component is classified as obsolete, though 696 pieces remain in stock. The fuse requires a 3AB or 3AG holder and is housed in a 1/4" x 1-1/4" (6.35mm x 31.80mm) package. Due to its obsolete status, equivalent and substitute parts from active manufacturers are necessary for ongoing system support and new designs requiring this electrical specification.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4"
Breaking Capacity @ Rated Voltage	200 A
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.250" Dia x 1.252" L (6.35mm x 31.80mm)

Substitute Part Grouping Explanation

Substitution of the 3SB 4 is determined by strict electrical and mechanical compatibility. All substitute parts must meet the following criteria:

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

Substitute parts are grouped into three categories:

Direct Manufacturer Substitutes (Bel Fuse Inc.): The 3SB 4-R is an active-status variant of the original part from the same manufacturer, offering identical electrical and mechanical specifications with improved RoHS3 compliance.

Direct Manufacturer Substitutes (Littelfuse Inc.): The 0313004.HXP, 0313004.MXP, and 0313004.VXP are active-status equivalents from Littelfuse Inc., series 313. These parts maintain all critical electrical parameters and mechanical compatibility while offering enhanced compliance certifications.

Similar Manufacturer Substitutes (Littelfuse Inc.): The 0313004.HXIDP and 0313004.VXIDP are active-status variants with identical electrical and mechanical specifications, differing only in internal construction or certification scope.

Parametric Equivalent (OptiFuse): The TSA-4A is a parametric equivalent from OptiFuse, series TSA, meeting all electrical and mechanical requirements with UL 248 certification.

Parameter Comparison

Parameter	3SB 4	3SB 4-R	0313004.HXP	0313004.MXP	0313004.VXP	0313004.HXIDP	0313004.VXIDP	TSA-4A
Manufacturer	Bel Fuse Inc.	Bel Fuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	OptiFuse
Current Rating (Amps)	4 A	4 A	4 A	4 A	4 A	4 A	4 A	4 A
Voltage Rating - AC	250 V	250 V	250 V	250 V	250 V	250 V	250 V	250 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"	3AB, 3AG, 1/4" x 1-1/4"
Breaking Capacity @ Rated Voltage	200 A	200 A	200 A	200 A	200 A	200 A	200 A	200 A
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Size / Dimension	0.250" Dia x 1.252" L (6.35mm x 31.80mm)	0.250" Dia x 1.252" L (6.35mm x 31.80mm)	0.250" Dia x 1.250" L (6.35mm x 31.75mm)	0.250" Dia x 1.250" L (6.35mm x 31.75mm)	0.250" Dia x 1.250" L (6.35mm x 31.75mm)	0.250" Dia x 1.250" L (6.35mm x 31.75mm)	0.250" Dia x 1.250" L (6.35mm x 31.75mm)	0.250" Dia x 1.252" L (6.35mm x 31.80mm)
Product Status	Obsolete	Active	Active	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CE, CSA, PSE, UL	CE, CSA, cULus, PSE	CE, CSA, K-MARK, PSE, UL	CE, CSA, K-MARK, PSE, UL	CE, CSA, KC, PSE, UL	CE, CSA, K-MARK, PSE, UL	CE, CSA, KC, PSE, UL	cULus, UL 248

Engineering Selection Recommendations

For Direct Replacement (Same Manufacturer): The 3SB 4-R from Bel Fuse Inc. is the primary substitute for the obsolete 3SB 4. Both parts share identical electrical and mechanical specifications. The 3SB 4-R offers active product status and ROHS3 compliance, making it suitable for new designs and ongoing system support.

For Cross-Manufacturer Substitution (Littelfuse Inc.): The 0313004.HXP, 0313004.MXP, 0313004.VXP, 0313004.HXIDP, and 0313004.VXIDP from Littelfuse Inc. series 313 are functionally equivalent alternatives. All five parts maintain the required 4 A, 250 V AC/DC slow-blow cartridge glass fuse specification with 200 A breaking capacity. These parts carry active product status and ROHS3 compliance. Selection among these five variants depends on specific certification requirements: 0313004.HXP, 0313004.MXP, and 0313004.HXIDP include K-MARK certification, while 0313004.VXP and 0313004.VXIDP include KC certification.

For Parametric Equivalence (OptiFuse): The TSA-4A from OptiFuse series TSA meets all electrical and mechanical parameters with UL 248 certification. This part is suitable for applications requiring UL 248 compliance specifically.

Compliance Considerations: All substitute parts are ROHS3 compliant and REACH unaffected, addressing environmental regulatory requirements. The original 3SB 4 is RoHS non-compliant; substitution with any active-status alternative improves regulatory compliance posture.

Frequently Asked Questions (FAQ)

Q: Can the 3SB 4-R directly replace the obsolete 3SB 4?

A: Yes. The 3SB 4-R is electrically and mechanically identical to the 3SB 4, with the same 4 A, 250 V AC/DC rating, slow-blow response, 200 A breaking capacity, and 3AB/3AG holder compatibility. The primary difference is active product status and ROHS3 compliance.

Q: Are Littelfuse 0313004 series parts compatible with 3AB and 3AG holders?

A: Yes. All Littelfuse 0313004 variants (HXP, MXP, VXP, HXIDP, VXIDP) are specified for 3AB and 3AG holder compatibility with identical 1/4" x 1-1/4" package dimensions.

Q: What is the difference between the five Littelfuse 0313004 variants?

A: All five variants—0313004.HXP, 0313004.MXP, 0313004.VXP, 0313004.HXIDP, and 0313004.VXIDP—share identical electrical and mechanical specifications. Differences exist only in certification scope: HXP, MXP, and HXIDP include K-MARK certification, while VXP and VXIDP include KC certification. Selection depends on regional or application-specific certification requirements.

Q: Is the OptiFuse TSA-4A a suitable substitute?

A: Yes. The TSA-4A meets all electrical and mechanical requirements: 4 A, 250 V AC/DC, slow-blow response, 200 A breaking capacity, and 3AB/3AG holder compatibility. It carries UL 248 certification and ROHS3 compliance. Selection of the TSA-4A is appropriate for applications requiring OptiFuse sourcing or UL 248 certification specifically.

Q: What are the dimensional differences between substitute parts?

A: The 3SB 4 and TSA-4A are specified at 0.250" Dia x 1.252" L (6.35mm x 31.80mm). The Littelfuse 0313004 series variants are specified at 0.250" Dia x 1.250" L (6.35mm x 31.75mm). This 0.02" (0.05mm) length difference is within standard mechanical tolerance for 3AB/3AG holder compatibility and does not affect functional performance.

Q: Are all substitute parts ROHS3 compliant?

A: Yes. All substitute parts listed—3SB 4-R, 0313004.HXP, 0313004.MXP, 0313004.VXP, 0313004.HXIDP, 0313004.VXIDP, and TSA-4A—are ROHS3 compliant. The original 3SB 4 is RoHS non-compliant.

Q: Which substitute offers the best inventory availability?

A: The 3SB 4-R from Bel Fuse Inc. has 17,807 pieces in stock, providing the highest availability among all substitutes listed.

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