3SB 8 Glass Cartridge Fuse 8A 250VAC Equivalent & Substitute Parts

Part Overview

The 3SB 8 is a glass cartridge fuse rated for 8A at 250VAC, manufactured by Bel Fuse Inc. This component is classified as obsolete, though 943 pieces remain in stock. The fuse requires a 3AB or 3AG holder and is designed for slow-blow response applications. Due to its obsolete status, identifying equivalent and substitute parts from active manufacturers is essential for ongoing system maintenance and new design implementations.

Key Parameters

Parameter	Value
Current Rating	8 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4"
Breaking Capacity @ Rated Voltage	200A
Operating Temperature Range	-55°C ~ 125°C
Mounting Type	Requires Holder

Substitute Part Grouping Explanation

Substitution eligibility for the 3SB 8 is determined by strict equivalence across the following parameters:

Current Rating: 8 A (exact match required)
Voltage Rating: 250 V AC (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" (exact match required)
Breaking Capacity: 200A (exact match required)
Operating Temperature: -55°C ~ 125°C (exact match required)

All substitute parts listed meet these criteria. Variations in secondary parameters such as melting I²t, DC cold resistance, and approval agencies do not disqualify substitution when primary electrical and mechanical parameters align.

Parameter Comparison

Part Number	Manufacturer	Current Rating	Voltage Rating (AC)	Response Time	Package / Case	Breaking Capacity	Operating Temperature	Product Status	RoHS Status
3SB 8	Bel Fuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Obsolete	RoHS non-compliant
3SB 8-R	Bel Fuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
0313008.HXP	Littelfuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
0313008.MXP	Littelfuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
0313008.VXP	Littelfuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
0313008.HXIDP	Littelfuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
0313008.VXIDP	Littelfuse Inc.	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant
TSA-8A	OptiFuse	8 A	250 V	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	200A	-55°C ~ 125°C	Active	ROHS3 Compliant

Engineering Selection Recommendations

All listed substitute parts are electrically and mechanically equivalent to the 3SB 8. Selection among active alternatives should be based on the following factors:

Product Status: The 3SB 8-R from Bel Fuse Inc. maintains the same manufacturer lineage as the original part while offering active product status and ROHS3 compliance. This represents the most direct replacement path.

Compliance Requirements: All Littelfuse parts (0313008.HXP, 0313008.MXP, 0313008.VXP, 0313008.HXIDP, 0313008.VXIDP) and the OptiFuse TSA-8A are ROHS3 compliant and carry active product status. Littelfuse parts carry expanded approval certifications including K-MARK and KC, while TSA-8A carries cULus and UL 248 certifications.

Inventory Availability: Littelfuse 0313008.MXP offers the highest inventory level at 12,200 pieces. OptiFuse TSA-8A provides 2,510 pieces, and 3SB 8-R offers 2,470 pieces.

Certification Alignment: For applications requiring specific regional approvals, verify that the selected substitute carries the necessary certifications (CE, CSA, PSE, UL, K-MARK, KC, cULus) for your target market.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts interchangeably with the 3SB 8?

A: Yes. All listed parts meet the core electrical and mechanical requirements: 8A current rating, 250V AC voltage rating, slow-blow response, 3AB/3AG package compatibility, and 200A breaking capacity. Physical dimensions and operating temperature ranges are identical across all parts.

Q: What is the difference between the Littelfuse variants (HXP, MXP, VXP, HXIDP, VXIDP)?

A: These variants differ in approval agency certifications and internal construction details not specified in the provided parameters. All variants maintain identical electrical ratings, package dimensions, and mechanical compatibility with the 3AB/3AG holder.

Q: Is the 3SB 8-R a direct replacement for the obsolete 3SB 8?

A: Yes. The 3SB 8-R is manufactured by the same company (Bel Fuse Inc.) and maintains identical electrical and mechanical specifications. The primary difference is that 3SB 8-R is active product status and ROHS3 compliant, whereas the original 3SB 8 is obsolete and RoHS non-compliant.

Q: Do I need to change my fuse holder when switching to a substitute part?

A: No. All substitute parts use the same 3AB and 3AG holder package as the original 3SB 8. Physical dimensions are 0.250" diameter by 1.252" length (6.35mm x 31.80mm), ensuring direct mechanical compatibility.

Q: Which substitute part should I select for new designs?

A: For new designs, select from parts with active product status and ROHS3 compliance. The 3SB 8-R, Littelfuse 0313008 series, and OptiFuse TSA-8A all meet these criteria. Verify that your selected part carries the required regional certifications for your application.

Q: Are there differences in melting I²t or DC cold resistance between these parts?

A: Yes. Melting I²t values range from 445 to 999.5, and DC cold resistance ranges from 0.0111 to 0.014 Ohms. These secondary parameters do not affect substitution eligibility when primary electrical and mechanical parameters are identical. Consult application-specific requirements if thermal response characteristics are critical.

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