Equivalent & Substitute Parts for BK/GMC-3A Glass Cartridge Fuse

Part Overview

The BK/GMC-3A is a 3 A, 250 V AC/DC glass cartridge fuse manufactured by Eaton - Electronics Division, designed for 5mm x 20mm holder applications. This fuse features medium blow response characteristics and is rated for 100 A breaking capacity at rated voltage. The part is currently classified as obsolete, necessitating identification of active equivalent and substitute components for ongoing system support and procurement.

Key Parameters

Parameter	Value
Current Rating	3 A
Voltage Rating (AC)	250 V
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Response Time	Medium Blow
Breaking Capacity @ Rated Voltage	100 A
Mounting Type	Requires Holder
Size / Dimension	0.205" Dia x 0.787" L (5.20mm x 20.00mm)

Substitute Part Grouping Explanation

Substitution for the BK/GMC-3A is determined by strict adherence to the following electrical and mechanical parameters:

Primary Substitution Criteria:

Current Rating: 3 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Consideration:

Response Time: Medium Blow (preferred for direct equivalence)
Breaking Capacity: 100 A (preferred for direct equivalence)

Parts are classified into two categories:

Direct Manufacturer Equivalents (Eaton GMC Series): Parts BK/GMC-3-R, BK1/GMC-3-R, and GMC-3-R meet all primary criteria with identical electrical and mechanical specifications. These parts differ only in product status (active vs. obsolete) and RoHS compliance levels.

Parametric Equivalents (Littelfuse Series 232): Parts 0232003.MXF19P, 0232003.MXF22P, 0232003.MXF34P, and 0232003.MXP meet all primary criteria and match the medium blow response and 100 A breaking capacity. Minor variations in melting I²t (17.19 vs. 19) and DC cold resistance (0.0226 vs. 0.026 Ohms) are within acceptable engineering tolerance for this component category.

Similar Parts with Voltage Deviations (Littelfuse Series 233 & 239): Parts 0233003.MXBP and 0233003.MXP operate at 125 V AC (not 250 V) and are classified as similar but not direct substitutes. Part 0239003.HXP operates at 250 V but features slow blow response (not medium blow) and higher melting I²t (129.51 vs. 19), making it unsuitable for direct replacement in medium blow applications.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage AC (V)	Response Time	Package	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
BK/GMC-3A	Eaton	3	250	Medium Blow	5x20mm	100	19	0.026	Obsolete	Non-compliant
BK/GMC-3-R	Eaton	3	250	Medium Blow	5x20mm	100	19	0.026	Active	ROHS3 Compliant
BK1/GMC-3-R	Eaton	3	250	Medium Blow	5x20mm	100	19	0.026	Active	ROHS3 Compliant
GMC-3-R	Eaton	3	250	Medium Blow	5x20mm	100	19	0.026	Active	ROHS3 Compliant
0232003.MXP	Littelfuse	3	250	Medium Blow	5x20mm	100	17.19	0.0226	Active	ROHS3 Compliant
0232003.MXF19P	Littelfuse	3	250	Medium Blow	5x20mm	100	17.19	0.0226	Active	ROHS3 Compliant
0232003.MXF22P	Littelfuse	3	250	Medium Blow	5x20mm	100	17.19	0.0226	Active	ROHS3 Compliant
0232003.MXF34P	Littelfuse	3	250	Medium Blow	5x20mm	100	17.19	0.0226	Active	ROHS3 Compliant
0233003.MXP	Littelfuse	3	125	Medium Blow	5x20mm	10000	26.24	0.0431	Active	ROHS3 Compliant
0233003.MXBP	Littelfuse	3	125	Medium Blow	5x20mm	10000	26.24	0.0431	Active	ROHS3 Compliant
0239003.HXP	Littelfuse	3	250	Slow Blow	5x20mm	100	129.51	0.04877	Active	ROHS3 Compliant

Engineering Selection Recommendations

Tier 1 - Direct Replacement (Recommended):

The Eaton GMC series parts BK/GMC-3-R, BK1/GMC-3-R, and GMC-3-R are direct functional equivalents to the obsolete BK/GMC-3A. All three parts maintain identical electrical specifications (3 A, 250 V AC, medium blow, 100 A breaking capacity) and mechanical form factor (5mm x 20mm). All three are active products with ROHS3 compliance, providing long-term procurement stability. Selection among these three variants should be based on internal part numbering conventions and inventory management practices.

Tier 2 - Parametric Equivalent (Alternative):

The Littelfuse Series 232 parts (0232003.MXP, 0232003.MXF19P, 0232003.MXF22P, 0232003.MXF34P) are parametric equivalents meeting all primary substitution criteria. These parts operate at identical voltage (250 V AC) and current (3 A) ratings with matching medium blow response and 100 A breaking capacity. Minor variations in melting I²t (17.19 vs. 19) and DC cold resistance (0.0226 vs. 0.026 Ohms) fall within acceptable tolerance ranges for this fuse category. All parts carry ROHS3 compliance and active product status. The 0232003.MXP variant offers the highest inventory availability (8,421 units).

Not Recommended for Direct Substitution:

Parts 0233003.MXP and 0233003.MXBP operate at 125 V AC, below the 250 V requirement of the original specification. Part 0239003.HXP, while rated at 250 V AC, features slow blow response characteristics incompatible with medium blow applications and exhibits significantly higher melting I²t (129.51), altering circuit protection behavior.

Frequently Asked Questions (FAQ)

Q: Can I use BK/GMC-3-R, BK1/GMC-3-R, or GMC-3-R interchangeably with the obsolete BK/GMC-3A?

A: Yes. All three parts are direct functional equivalents with identical electrical and mechanical specifications. They differ only in product status (all active) and RoHS compliance (all ROHS3 compliant). Selection should follow your organization's part numbering and procurement protocols.

Q: What is the difference between the Eaton GMC series and Littelfuse Series 232 fuses?

A: Both meet the primary substitution criteria (3 A, 250 V AC, 5mm x 20mm, medium blow). The Littelfuse Series 232 parts exhibit slightly lower melting I²t (17.19 vs. 19) and DC cold resistance (0.0226 vs. 0.026 Ohms). These variations are within acceptable engineering tolerance for this component category and do not affect functional compatibility in standard applications.

Q: Why are the Littelfuse Series 233 parts (0233003.MXP, 0233003.MXBP) listed but not recommended?

A: Series 233 parts are rated at 125 V AC, not 250 V AC. Using a 125 V fuse in a 250 V circuit violates electrical safety requirements and is not permitted.

Q: Can I substitute the Littelfuse 0239003.HXP (slow blow) for the medium blow BK/GMC-3A?

A: No. The 0239003.HXP features slow blow response with melting I²t of 129.51, compared to the medium blow specification with I²t of 19. This fundamental difference in response characteristics alters circuit protection behavior and makes it unsuitable for direct replacement.

Q: Are all substitute parts RoHS compliant?

A: The original BK/GMC-3A is RoHS non-compliant. All recommended substitute parts (Eaton GMC series and Littelfuse Series 232) are ROHS3 compliant, meeting current environmental regulations.

Q: What certifications do the substitute parts carry?

A: Eaton GMC series parts carry CSA, KC-MARK, MITI, and UL approvals. Littelfuse Series 232 parts carry CE, KC, and PSE approvals. Both meet the approval requirements for this fuse category.

Q: Does package size remain constant across all substitutes?

A: Yes. All substitute parts maintain the 5mm x 20mm form factor, ensuring mechanical compatibility with existing fuse holders.

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