Equivalent & Substitute Parts for BK1/GMD-4-R Glass Cartridge Fuse

Part Overview

The BK1/GMD-4-R is a 4 A, 250 V AC/DC glass cartridge fuse manufactured by Eaton - Electronics Division. This slow-blow fuse cartridge operates in a 5mm x 20mm form factor and requires a separate holder for installation. The part maintains active product status with 1113 pieces in current inventory.

Substitute parts are necessary when the primary part becomes unavailable, when alternative certifications are required for specific regional markets, or when design requirements necessitate different electrical characteristics such as breaking capacity or melting I²t values.

Key Parameters

Parameter	Value
Current Rating	4 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	200 A
Melting I²t	300
DC Cold Resistance	0.048 Ohms
RoHS Status	ROHS3 Compliant

Substitute Part Grouping Explanation

Substitution eligibility for the BK1/GMD-4-R is determined by the following mandatory parameters:

Primary Substitution Criteria:

Current Rating: 4 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)
Response Time: Slow Blow (exact match required)
Mounting Type: Requires Holder (exact match required)

Secondary Compatibility Parameters:

Breaking Capacity @ Rated Voltage: 40 A to 200 A (acceptable range)
Melting I²t: 68.3 to 410 (acceptable range)
DC Cold Resistance: 0.0139 to 0.048 Ohms (acceptable range)

Parts meeting all primary criteria are classified as parametric equivalents. Parts meeting primary criteria but with different voltage ratings or current ratings are classified as similar parts and are not suitable for direct substitution.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Series	Current (A)	Voltage AC (V)	Package	Breaking Capacity (A)	Melting I²t	DC Resistance (Ohms)	Approval Agency	Inventory (Pcs)
BK1/GMD-4-R	Eaton	GMD	4	250	5x20mm	200	300	0.048	PSE/JET, UR	1113
BK/GDC-4A	Eaton	GDC	4	250	5x20mm	40	71.8	0.0139	cULus, IMQ, MITI/JET	1848
BK/GMD-4-R	Eaton	GMD	4	250	5x20mm	200	300	0.048	PSE/Jet, UL	3754
BK/S506-4-R	Eaton	S506	4	250	5x20mm	40	71.8	0.0139	BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, VDE	742
GDC-4A	Eaton	GDC	4	250	5x20mm	40	71.8	0.0139	cURus, IMQ, MITI/JET	1078
GMD-4-R	Eaton	GMD	4	250	5x20mm	200	300	0.048	PSE/Jet, UL	911
0034.3123	SCHURTER	FST 5x20	4	250	5x20mm	40	68.3	Not specified	CCC, cURus, PSE/JET, VDE	58155
0034.5049	SCHURTER	FTT 5x20	4	250	5x20mm	35	410	Not specified	cURus	3776
0034.5623.11	SCHURTER	SMD-FST	4	250	5x20mm	40	68.3	Not specified	cURus, VDE	1838
0213004.MXP	Littelfuse	213	4	250	5x20mm	40	226.505	0.017	BSI, CCC, CE, CSA, PSE, SEMKO, UR, VDE	5552

Engineering Selection Recommendations

Eaton GMD Series (BK/GMD-4-R, GMD-4-R): These parts are direct parametric equivalents to the BK1/GMD-4-R with identical electrical characteristics. Both maintain 200 A breaking capacity and 300 melting I²t. Selection between BK/GMD-4-R and GMD-4-R depends on regional certification requirements. BK/GMD-4-R carries PSE/Jet and UL approvals with 3754 pieces in inventory. GMD-4-R carries PSE/Jet and UL approvals with 911 pieces in inventory.

Eaton GDC Series (BK/GDC-4A, GDC-4A): These parts meet all primary substitution criteria but feature reduced breaking capacity (40 A versus 200 A) and lower melting I²t (71.8 versus 300). Selection is appropriate for applications with lower fault current requirements. GDC-4A carries cULus, IMQ, and MITI/JET approvals with 1078 pieces in inventory.

Eaton S506 Series (BK/S506-4-R): This part meets all primary substitution criteria with 40 A breaking capacity and 71.8 melting I²t. It carries the broadest certification scope including BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, and VDE. This part is suitable for applications requiring multiple regional certifications.

SCHURTER FST 5x20 (0034.3123): This part meets all primary substitution criteria with 40 A breaking capacity and 68.3 melting I²t. It carries CCC, cURus, PSE/JET, and VDE approvals. Inventory availability is highest at 58155 pieces.

SCHURTER FTT 5x20 (0034.5049): This part meets all primary substitution criteria with 35 A breaking capacity and 410 melting I²t. It carries cURus approval only. Operating temperature range is -40°C to 85°C.

SCHURTER SMD-FST (0034.5623.11): This part meets all primary substitution criteria with 40 A breaking capacity and 68.3 melting I²t. It carries cURus and VDE approvals with 1838 pieces in inventory.

Littelfuse 213 Series (0213004.MXP): This part meets all primary substitution criteria with 40 A breaking capacity and 226.505 melting I²t. It carries BSI, CCC, CE, CSA, PSE, SEMKO, UR, and VDE approvals with 5552 pieces in inventory.

Frequently Asked Questions (FAQ)

Q: Can I substitute a 4 A, 125 V fuse for the BK1/GMD-4-R?

A: No. The BK1/GMD-4-R operates at 250 V AC. Substituting a 125 V fuse violates the primary substitution criterion of exact voltage match and creates a safety hazard.

Q: What is the difference between parts with 200 A breaking capacity and 40 A breaking capacity?

A: Breaking capacity defines the maximum fault current the fuse can safely interrupt without rupturing the fuse body. The BK1/GMD-4-R has 200 A breaking capacity. Substitutes with 40 A breaking capacity are suitable only for applications where the maximum available fault current does not exceed 40 A. Verify the system's available fault current before selecting a lower breaking capacity substitute.

Q: Are all 4 A, 250 V, 5x20mm glass cartridge fuses interchangeable?

A: No. While these parts share identical primary parameters, they differ in breaking capacity, melting I²t, and approval certifications. These differences affect performance in fault conditions and regional compliance. Selection must account for the specific application's fault current requirements and regional certification mandates.

Q: What does "Requires Holder" mean?

A: This fuse type is a cartridge that must be installed in a separate fuse holder. It is not a plug-in fuse. Verify that your equipment uses a compatible 5mm x 20mm fuse holder before ordering.

Q: Why do some substitutes have different melting I²t values?

A: Melting I²t defines the thermal energy required to melt the fuse element. Different manufacturers use different fuse element materials and designs, resulting in different melting I²t values. Higher melting I²t indicates greater tolerance to transient overcurrents before the fuse opens. Select based on your application's inrush current characteristics.

Q: Which substitute has the best inventory availability?

A: SCHURTER 0034.3123 (FST 5x20 series) has the highest inventory at 58155 pieces.

Q: Can I use a substitute with a different approval agency?

A: Yes, provided the substitute carries approvals required by your regional market and application standards. For example, if your application requires UL certification, select a substitute carrying UL approval. The BK/S506-4-R carries the broadest certification scope across multiple regions.

Q: What is the operating temperature range for the BK1/GMD-4-R?

A: The operating temperature range is not specified in the provided data. Verify this specification with the manufacturer if temperature extremes are a design consideration.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message