Equivalent & Substitute Parts for BK/GMD-1A Glass Cartridge Fuse

Part Overview

The BK/GMD-1A is a 1 A, 250 V AC/DC glass cartridge fuse manufactured by Eaton Electronics Division in a 5mm x 20mm package format. This fuse is classified as obsolete product status. Due to its obsolete designation, equivalent and substitute parts with active product status are available from Eaton and alternative manufacturers to maintain circuit protection functionality in applications requiring 1 A slow-blow fuse cartridges at 250 V AC/DC ratings.

Key Parameters

Parameter	Value
Current Rating	1 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Package / Case	5mm x 20mm
Response Time	Slow Blow
Mounting Type	Requires Holder
Breaking Capacity @ Rated Voltage	35 A
Size / Dimension	0.205" Dia x 0.787" L (5.20mm x 20.00mm)

Substitute Part Grouping Explanation

Substitution for the BK/GMD-1A is determined by strict equivalence across the following electrical and mechanical parameters:

Critical Matching Parameters:

Current Rating: 1 A (exact match required)
Voltage Rating (AC): 250 V (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Package / Case: 5mm x 20mm (exact match required)
Response Time: Slow Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Parameters (Allowable Variation):

Breaking Capacity @ Rated Voltage: 35 A or higher
Melting I²t: 6.45 to 12 (within acceptable range for slow-blow characteristic)
DC Cold Resistance: 0.0757 to 0.3065 Ohms
Approval Agencies: CSA, UL, PSE/JET, IMQ, VDE, BSI, CCC, SEMKO, cURus, MITI/JET

All substitute parts listed maintain identical electrical performance characteristics and physical form factor compatibility with the original BK/GMD-1A specification.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage AC (V)	Breaking Capacity (A)	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
BK/GMD-1A	Eaton	1	250	35	12	—	Obsolete	Non-compliant
BK/GMD-1-R	Eaton	1	250	35	12	0.3065	Active	ROHS3 Compliant
BK/GDC-1A	Eaton	1	250	35	6.45	0.0757	Active	ROHS3 Compliant
BK/S506-1-R	Eaton	1	250	35	6.45	0.0757	Active	ROHS3 Compliant
BK1/GMD-1-R	Eaton	1	250	100	12	0.3065	Active	ROHS3 Compliant
BK1/S506-1-R-R	Eaton	1	250	35	6.45	0.0757	Active	ROHS3 Compliant
GDC-1A	Eaton	1	250	35	6.45	0.0757	Active	ROHS3 Compliant
GMD-1-R	Eaton	1	250	35	12	0.3065	Active	ROHS3 Compliant
S506-1-R	Eaton	1	250	35	6.45	0.0757	Active	ROHS3 Compliant
0239001.HXP	Littelfuse	1	250	35	11.295	0.2965	Active	ROHS3 Compliant
0239001.MXP	Littelfuse	1	250	35	11.295	0.2965	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: BK/GMD-1-R

The BK/GMD-1-R is the direct active-status equivalent from Eaton Electronics Division. It maintains identical electrical characteristics to the obsolete BK/GMD-1A, including 1 A current rating, 250 V AC voltage rating, 35 A breaking capacity, and 12 Melting I²t value. The BK/GMD-1-R holds active product status and is ROHS3 compliant, making it the preferred replacement for new designs and existing applications.

Alternative Eaton Options:

BK/S506-1-R and S506-1-R provide equivalent functionality with broader international certification coverage (BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, VDE). These parts feature a lower Melting I²t value of 6.45 compared to the original 12, resulting in faster response characteristics within the slow-blow category. Selection of these alternatives is appropriate when international compliance certifications are required.

BK/GDC-1A and GDC-1A offer similar electrical performance with certifications from cURus, IMQ, and MITI/JET. These parts are suitable for applications requiring Japanese market compliance (MITI/JET).

BK1/GMD-1-R provides enhanced breaking capacity of 100 A at rated voltage, compared to 35 A in the original specification. This part is selected when higher fault current withstand capability is required.

Alternative Manufacturer Option: Littelfuse 0239001.HXP

The Littelfuse 0239001.HXP cartridge fuse meets all critical electrical and mechanical parameters. It provides operating temperature range specification (-55°C ~ 125°C) and holds certifications from CE, CSA, KC, PSE, and UL. The Melting I²t value of 11.295 closely approximates the original 12 value. This part is suitable for applications where multi-source component availability is required.

Frequently Asked Questions (FAQ)

Q: Can BK/GMD-1A be directly replaced with BK/GMD-1-R?

A: Yes. BK/GMD-1-R is the direct active-status equivalent. Both parts share identical electrical ratings (1 A, 250 V AC), fuse type (cartridge glass), package format (5mm x 20mm), response time (slow blow), and breaking capacity (35 A). The primary difference is product status: BK/GMD-1A is obsolete while BK/GMD-1-R is active.

Q: What is the difference between GMD and S506 series fuses?

A: Both series meet the same electrical specifications for the 1 A, 250 V application. The primary difference is certification scope. S506 series fuses carry broader international certifications (BSI, CCC, SEMKO, VDE) compared to GMD series. S506 fuses also feature a lower Melting I²t value (6.45 versus 12), resulting in faster response within the slow-blow category.

Q: Are Littelfuse 0239001.HXP and Eaton GMD-1-R interchangeable?

A: Yes, within the specified electrical and mechanical parameters. Both parts are 1 A, 250 V AC/DC glass cartridge fuses in 5mm x 20mm packages with 35 A breaking capacity and slow-blow response time. The Littelfuse part has a Melting I²t of 11.295 compared to 12 for the Eaton part, representing a negligible difference in thermal response. Certification differences exist: Littelfuse holds CE, CSA, KC, PSE, UL certifications while Eaton GMD-1-R holds CSA, PSE/JET, UL certifications.

Q: Does the fuse holder type affect substitution compatibility?

A: No. All listed substitute parts require a holder, consistent with the original BK/GMD-1A specification. The 5mm x 20mm package format is standardized across all substitute parts, ensuring mechanical compatibility with existing fuse holders designed for this cartridge size.

Q: What does "Slow Blow" response time mean?

A: Slow-blow fuses tolerate temporary current surges without opening, responding only to sustained overcurrent conditions. All substitute parts maintain this slow-blow characteristic, ensuring they provide equivalent protection behavior in applications designed for the original BK/GMD-1A.

Q: Why do some substitute parts have different Melting I²t values?

A: Melting I²t represents the thermal energy required to melt the fuse element. Variations between 6.45 and 12 reflect different fuse element designs while maintaining the same 1 A current rating and slow-blow response classification. These variations remain within acceptable parameters for slow-blow fuse operation and do not affect functional compatibility in standard applications.

Q: Is RoHS compliance required for my application?

A: The original BK/GMD-1A is RoHS non-compliant. All active substitute parts listed (Eaton and Littelfuse) are ROHS3 compliant. If your application or supply chain requires RoHS compliance, any of the active substitute parts satisfy this requirement.

Q: Can BK1/GMD-1-R be used as a direct replacement?

A: BK1/GMD-1-R is electrically and mechanically compatible but features enhanced breaking capacity (100 A versus 35 A). This higher breaking capacity provides additional fault current withstand capability. Selection of this part is appropriate when applications require higher breaking capacity ratings. Standard applications requiring only 35 A breaking capacity can use this part without adverse effects.

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