3AG 7 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 3AG 7 is a 7 A, 250 V AC/DC fast-blow glass cartridge fuse manufactured by Bel Fuse Inc. This component is classified as obsolete, requiring identification of active equivalent alternatives for new designs and ongoing maintenance applications. The 3AG form factor (1/4" x 1-1/4") with 3AB/3AG holder mounting remains a standard in industrial and consumer electronics. Substitute parts must maintain identical electrical ratings, mechanical dimensions, and holder compatibility to ensure direct replacement without circuit redesign.

Key Parameters

Parameter	Value
Current Rating	7 A
Voltage Rating (AC)	250 V
Response Time	Fast Blow
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (6.35mm x 31.80mm)
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	200 A
Operating Temperature Range	-55°C ~ 125°C

Substitute Part Grouping Explanation

Substitution validity for the 3AG 7 fuse is determined by strict equivalence across the following parameters:

Current Rating: 7 A (exact match required)
Voltage Rating: 250 V AC minimum (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Package / Case: 3AB, 3AG form factor with 1/4" x 1-1/4" dimensions (exact match required)
Response Time: Fast Blow (exact match required)
Breaking Capacity: 200 A @ rated voltage (exact match required)
Mounting: Requires Holder compatibility (exact match required)

All substitute parts listed below meet these criteria and are therefore electrically and mechanically interchangeable with the main part number 3AG 7.

Parameter Comparison

Parameter	3AG 7 (Bel Fuse)	3AG 7-R (Bel Fuse)	0312007.HXP (Littelfuse)	0034.5143 (SCHURTER)	FSA-7A (OptiFuse)
Current Rating (Amps)	7 A	7 A	7 A	7 A	7 A
Voltage Rating - AC	250 V	250 V	250 V	250 V	250 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Fuse Type	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"
Breaking Capacity @ Rated Voltage	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
Product Status	Obsolete	Active	Active	Obsolete	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For applications requiring the 3AG 7 fuse, the following active alternatives are available:

3AG 7-R (Bel Fuse Inc.) is the direct manufacturer upgrade from the obsolete 3AG 7. This part maintains identical electrical and mechanical specifications while offering ROHS3 compliance and active product status. Inventory availability is substantial at 2195 units.

0312007.HXP (Littelfuse Inc.) provides equivalent functionality with ROHS3 compliance and active status. This part is supported by CE, CSA, KC, PSE, and UL certifications. Littelfuse is an established fuse manufacturer with broad market distribution.

FSA-7A (OptiFuse) is an active alternative with ROHS3 compliance and cULus/UL 248 certification. This part offers the highest inventory availability at 4205 units and is suitable for new design implementations.

0034.5143 (SCHURTER Inc.) is a parametric equivalent with ROHS3 compliance but carries obsolete product status. This part should be considered only for legacy system maintenance where existing inventory exists.

For new designs, select from active parts: 3AG 7-R, 0312007.HXP, or FSA-7A. For legacy system support, 0034.5143 remains available but with limited long-term supply assurance.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts as a direct replacement for the 3AG 7?

A: Yes. All listed substitute parts are electrically and mechanically equivalent. They share identical current ratings (7 A), voltage ratings (250 V AC), response characteristics (fast blow), and physical dimensions (1/4" x 1-1/4"). All mount in standard 3AB/3AG holders without modification.

Q: What is the difference between the 3AG 7 and 3AG 7-R?

A: Both parts are manufactured by Bel Fuse Inc. and share identical electrical and mechanical specifications. The primary differences are product status (3AG 7 is obsolete; 3AG 7-R is active) and RoHS compliance (3AG 7 is non-compliant; 3AG 7-R is ROHS3 compliant). The 3AG 7-R is the recommended upgrade path.

Q: Are there dimensional differences between manufacturers?

A: All substitute parts conform to the 3AB/3AG standard form factor of 1/4" x 1-1/4" (6.35mm x 31.80mm). Minor variations in DC cold resistance and melting I²t values exist but do not affect holder compatibility or circuit protection function at rated specifications.

Q: Which substitute part should I select for a new design?

A: For new designs, select from active parts with current certifications: 3AG 7-R (Bel Fuse), 0312007.HXP (Littelfuse), or FSA-7A (OptiFuse). All three offer ROHS3 compliance and established supply chains. FSA-7A offers the highest inventory availability.

Q: Can I mix different manufacturers' fuses in the same application?

A: Yes, provided all parts meet the specified electrical and mechanical parameters. However, for consistency in maintenance and inventory management, standardizing on a single manufacturer is recommended.

Q: What certifications are relevant for my application?

A: All substitute parts carry UL certification. Additional certifications vary by manufacturer: 3AG 7-R includes CE, CSA, cURus, and PSE; 0312007.HXP includes CE, CSA, KC, PSE, and UL; FSA-7A includes cULus and UL 248. Verify that your application requirements align with the certifications of your selected part.

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