3AG 8 Equivalent & Substitute Parts

Part Overview

The 3AG 8 is an 8A 250VAC glass cartridge fuse manufactured by Bel Fuse Inc., designed for use with 3AB and 3AG holders. This component is classified as obsolete, making equivalent substitutes necessary for ongoing system maintenance and new designs. The fuse provides fast-blow response characteristics suitable for circuit protection applications requiring 8 ampere current limitation at 250 volts AC/DC.

Substiute Parts

3AG 8

Bel Fuse Inc.In Stock: 7993AG 8 Datasheet

Current PartRFQ

3AG 8-R

Bel Fuse Inc.In Stock: 128803AG 8-R Datasheet

DirectRFQ

FSA-8A

OptiFuseIn Stock: 1851FSA-8A Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 3AG 8 is determined by strict equivalence across the following critical 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: Fast Blow (exact match required)
• Physical Package: 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 identified substitutes meet these parameters without deviation. Substitution is valid based on mechanical and electrical compatibility within the specified holder systems.

Parameter Comparison

Engineering Selection Recommendations

The 3AG 8 is obsolete and should be replaced with an active equivalent. Two direct substitutes are available:

3AG 8-R (Bel Fuse Inc.) is the primary substitute, offering identical electrical and mechanical specifications with active product status. This part maintains Bel Fuse Inc. manufacturer continuity and includes ROHS3 compliance. Certifications include CE, CSA, cURus, and PSE.

FSA-8A (OptiFuse) is a parametric equivalent providing identical core electrical and mechanical performance. This part carries ROHS3 compliance and UL 248 certification through cULus and UL approvals. Selection between 3AG 8-R and FSA-8A depends on existing supply chain relationships and certification requirements specific to the application.

Frequently Asked Questions (FAQ)

Q: Can the 3AG 8-R directly replace the obsolete 3AG 8?

A: Yes. The 3AG 8-R is electrically and mechanically identical to the 3AG 8, with matching current rating (8A), voltage rating (250V AC), fuse type (cartridge glass), response time (fast blow), physical dimensions (0.250" Dia x 1.252" L), and breaking capacity (200A). Both require the same 3AB or 3AG holder.

Q: What is the difference between 3AG 8-R and FSA-8A?

A: Both parts meet identical electrical and mechanical specifications for 8A 250V AC/DC fast-blow cartridge fuses in 3AG package format. The primary differences are manufacturer (Bel Fuse Inc. versus OptiFuse) and certification bodies. The 3AG 8-R includes CSA and PSE certifications, while FSA-8A includes UL 248 certification.

Q: Are there RoHS compliance differences between substitutes?

A: Yes. The original 3AG 8 is RoHS non-compliant. Both substitutes, 3AG 8-R and FSA-8A, are ROHS3 compliant, making them suitable for applications requiring RoHS compliance.

Q: Will these substitutes work in existing 3AG holders?

A: Yes. All three parts share identical physical dimensions (0.250" Dia x 1.252" L) and are designed for 3AB and 3AG holder systems. No holder modification is required.

Q: What is the melting I²t difference between substitutes?

A: The 3AG 8 and 3AG 8-R both specify 184 A²s melting I²t. The FSA-8A specifies 239.9 A²s. This difference reflects manufacturer-specific thermal characteristics but does not affect substitution validity, as all three parts maintain identical current rating and response time classification.