BK/AGC-B-5 Equivalent & Substitute Parts Reference

Part Overview

The BK/AGC-B-5 is a 5 A 250 V AC/DC fast-blow glass fuse cartridge manufactured by Eaton - Electronics Division. This component operates within the 3AB and 3AG package standard (1/4" x 1-1/4" form factor) and requires a compatible fuse holder for installation. The part is classified as obsolete, necessitating identification of active equivalent alternatives that maintain identical electrical and mechanical specifications for direct circuit replacement.

Key Parameters

Parameter	Value
Current Rating	5 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Fast Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4"
Size / Dimension	0.250" Dia x 1.250" L (6.35mm x 31.75mm)
Breaking Capacity @ Rated Voltage	200 A
Melting I²t	131.5
DC Cold Resistance	0.019 Ohms
Operating Temperature Range	-55°C ~ 125°C
Approval Agencies	CSA, UL
Mounting Type	Requires Holder

Substitute Part Grouping Explanation

Substitution eligibility for the BK/AGC-B-5 is determined by strict equivalence across the following critical parameters:

Primary Substitution Criteria:

Current Rating: 5 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Fast Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Compatibility Parameters:

Operating Temperature Range: -55°C ~ 125°C (minimum requirement)
Approval Agencies: CSA, UL (minimum requirement)
Breaking Capacity @ Rated Voltage: 200 A (minimum requirement)

Substitute parts are grouped into two categories:

Category 1: Parametric Equivalents (Eaton - Electronics Division) Parts AGC-5-R, BK-AGC-B-5-R, BK/AGC-5-R, BK/AGC-5BX, and BK/AGC-5PP-R maintain identical electrical and mechanical specifications to the main part. These components differ only in product status (active vs. obsolete) and packaging designation (bulk vs. standard). All Category 1 substitutes are manufactured by Eaton and carry active product status.

Category 2: Similar Equivalents (Littelfuse Inc.) Parts 0312005.HXP, 0312005.MXCCP, 0312005.MXP, and 0312005.TXP meet all primary substitution criteria and operate within the same electrical envelope. These components are manufactured by Littelfuse and carry active product status. Melting I²t values differ (50 vs. 131.5), indicating different thermal response characteristics within the fast-blow classification.

Category 3: Different Package Standard (Not Recommended) Part 0224005.MXUP operates at 5 A, 250 V with fast-blow response but uses the 2AG package standard (5mm x 15mm axial form factor), which is mechanically incompatible with 3AB/3AG holders. This part is listed for reference only and does not constitute a direct substitute.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Current Rating (A)	Voltage (V AC)	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ohms)	Product Status	RoHS Status
BK/AGC-B-5	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Obsolete	Non-compliant
AGC-5-R	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Active	ROHS3 Compliant
BK-AGC-B-5-R	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Active	Not specified
BK/AGC-5-R	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Active	ROHS3 Compliant
BK/AGC-5BX	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Active	Not specified
BK/AGC-5PP-R	Eaton	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	131.5	0.019	Active	Not specified
0312005.HXP	Littelfuse	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	50	0.0224	Active	ROHS3 Compliant
0312005.MXCCP	Littelfuse	5	250	3AB, 3AG, 1/4" x 1-1/4"	100	50	0.0224	Active	ROHS3 Compliant
0312005.MXP	Littelfuse	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	50	0.0224	Active	ROHS3 Compliant
0312005.TXP	Littelfuse	5	250	3AB, 3AG, 1/4" x 1-1/4"	200	50	0.0224	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: Eaton Active Equivalents

For direct replacement of the obsolete BK/AGC-B-5, the Eaton-manufactured active equivalents AGC-5-R, BK/AGC-5-R, BK/AGC-5BX, and BK/AGC-5PP-R provide identical electrical performance and mechanical compatibility. These parts maintain the original melting I²t value of 131.5 and DC cold resistance of 0.019 Ohms. AGC-5-R and BK/AGC-5-R carry ROHS3 compliance certification, meeting current regulatory requirements. All Eaton equivalents retain the 200 A breaking capacity and are approved by CSA and UL.

Secondary Recommendation: Littelfuse Active Equivalents

The Littelfuse 312 series parts (0312005.HXP, 0312005.MXP, 0312005.TXP) satisfy all primary substitution criteria and carry active product status with ROHS3 compliance. These components operate at identical current, voltage, and package specifications. The melting I²t value of 50 indicates faster thermal response compared to the original part (131.5), while maintaining fast-blow classification. The 0312005.HXP and 0312005.MXP variants retain the 200 A breaking capacity. The 0312005.MXCCP variant operates at reduced breaking capacity (100 A) and is suitable only for applications where this lower rating is acceptable.

Not Recommended: Different Package Standards

The Littelfuse 0224004.MXUP operates at 5 A, 250 V but uses the 2AG package (5mm x 15mm axial), which is mechanically incompatible with 3AB/3AG fuse holders. This part cannot serve as a direct substitute.

Frequently Asked Questions (FAQ)

Q: Can I use an Eaton substitute in place of the obsolete BK/AGC-B-5?

A: Yes. The active Eaton equivalents AGC-5-R, BK/AGC-5-R, BK/AGC-5BX, and BK/AGC-5PP-R are direct parametric replacements. All maintain identical current rating (5 A), voltage rating (250 V AC), package standard (3AB, 3AG, 1/4" x 1-1/4"), breaking capacity (200 A), and thermal characteristics (melting I²t 131.5). Physical dimensions and holder compatibility are identical.

Q: What is the difference between Eaton and Littelfuse substitutes?

A: Both manufacturers provide 5 A, 250 V fast-blow fuses in the 3AB/3AG package with 200 A breaking capacity (except 0312005.MXCCP at 100 A). The primary difference is melting I²t: Eaton parts retain the original value of 131.5, while Littelfuse parts operate at 50. This indicates Littelfuse fuses respond thermally faster within the fast-blow classification. Both carry CSA and UL approvals and ROHS3 compliance (where specified).

Q: Can I substitute a Littelfuse fuse for an Eaton fuse in the same circuit?

A: Substitution is permissible when the application tolerates the faster thermal response of the Littelfuse part (melting I²t 50 vs. 131.5). Both maintain fast-blow response and identical electrical ratings. Verify that circuit protection requirements do not depend on the specific thermal time constant of the original part. Both are approved by CSA and UL.

Q: What does the melting I²t value indicate?

A: Melting I²t is a thermal energy parameter that characterizes fuse response time. The original BK/AGC-B-5 has a melting I²t of 131.5, while Littelfuse equivalents operate at 50. Lower I²t values indicate faster thermal response to overcurrent conditions. Both values fall within the fast-blow classification and are suitable for general-purpose circuit protection.

Q: Are all substitute parts RoHS compliant?

A: The original BK/AGC-B-5 is RoHS non-compliant. Active Eaton equivalents AGC-5-R and BK/AGC-5-R are ROHS3 compliant. Littelfuse parts 0312005.HXP, 0312005.MXCCP, 0312005.MXP, and 0312005.TXP are ROHS3 compliant. If RoHS compliance is required for your application, select from the compliant alternatives.

Q: Can I use the 0224005.MXUP as a substitute?

A: No. Although the 0224005.MXUP operates at 5 A, 250 V with fast-blow response, it uses the 2AG package standard (5mm x 15mm axial form factor). This is mechanically incompatible with 3AB/3AG fuse holders. This part cannot be installed in the same holder and is not a direct substitute.

Q: What is the difference between BK/AGC-5-R and BK-AGC-B-5-R?

A: Both are Eaton-manufactured active equivalents with identical electrical and mechanical specifications. The naming convention differs (slash vs. hyphen notation), but the parts are functionally equivalent. Both maintain 5 A, 250 V ratings, 3AB/3AG package compatibility, 200 A breaking capacity, and 131.5 melting I²t. Selection between these variants may depend on supplier availability or internal part numbering systems.

Q: Do all substitutes fit in the same fuse holder?

A: Yes. All recommended substitutes (Eaton AGC-5-R, BK/AGC-5-R, BK/AGC-5BX, BK/AGC-5PP-R, and Littelfuse 0312005 series) maintain the 3AB/3AG package standard with dimensions 0.250" Dia x 1.250" L (6.35mm x 31.75mm). Physical compatibility with existing holders is confirmed. The 0224005.MXUP (2AG package) is not compatible.

Q: What approvals do the substitute parts carry?

A: All recommended substitutes carry CSA and UL approvals, matching the original part's certification. Littelfuse parts carry additional approvals: CE, KC, PSE (0312005.HXP, 0312005.MXP, 0312005.TXP) and CE, KC, METI (0312005.MXCCP). These additional certifications expand geographic and market applicability.

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