Equivalent & Substitute Parts for BK/S504-1.6A Glass Cartridge Fuse

Part Overview

The BK/S504-1.6A is a 1.6 A, 250 V AC/DC glass cartridge fuse manufactured by Eaton - Electronics Division in a 5mm x 20mm form factor with slow-blow response characteristics. This part is classified as obsolete, requiring identification of active equivalent and substitute components for ongoing circuit protection applications. The obsolete status necessitates sourcing from active product lines that maintain electrical and mechanical compatibility with the original specification.

Key Parameters

Parameter	Value
Current Rating	1.6 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

Substitute Part Grouping Explanation

Substitution eligibility for the BK/S504-1.6A is determined by strict equivalence across the following parameters:

Primary Equivalence Criteria:

Current Rating: 1.6 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 Compatibility Parameters:

Breaking Capacity @ Rated Voltage: 35 A or higher
Melting I²t: Variation permitted within thermal design envelope
DC Cold Resistance: Variation permitted within operational limits
Approval Agencies: Must include relevant certifications for target application

Parts are grouped into three categories:

Direct Manufacturer Equivalents (Eaton - Electronics Division): Active products from the same manufacturer with identical electrical and mechanical specifications.
Parametric Equivalents (Eaton - Electronics Division): Active Eaton products meeting all primary equivalence criteria with variations in secondary parameters such as melting I²t or breaking capacity.
Cross-Manufacturer Equivalents: Active products from alternative manufacturers (Littelfuse Inc., SCHURTER Inc.) meeting all primary equivalence criteria.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage (V AC)	Fuse Type	Package	Response	Breaking Capacity (A)	Melting I²t	DC Resistance (Ω)	Product Status	RoHS Status
BK/S504-1.6A	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	10	0.039	Obsolete	Non-compliant
BK/S506-1.6-R	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	21.7	0.0425	Active	ROHS3 Compliant
BK/GDC-1.6A	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	21.7	0.0425	Active	ROHS3 Compliant
BK/GMD-1.6-R	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	100	27	0.124	Active	ROHS3 Compliant
BK1/GMD-1.6-R	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	100	27	0.124	Active	ROHS3 Compliant
GDC-1.6A	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	21.7	0.0425	Active	ROHS3 Compliant
GMD-1.6-R	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	100	27	0.124	Active	ROHS3 Compliant
S506-1.6-R	Eaton	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	21.7	0.0425	Active	ROHS3 Compliant
021801.6MXP	Littelfuse	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	23.35	0.0336	Active	ROHS3 Compliant
0034.3119	SCHURTER	1.6	250	Cartridge, Glass	5x20mm	Slow Blow	35	10.5	Not specified	Active	ROHS3 Compliant

Engineering Selection Recommendations

Eaton Direct Manufacturer Equivalents (Recommended Primary Selection):

The BK/S506-1.6-R, BK/GDC-1.6A, and S506-1.6-R represent the most direct substitutes from Eaton - Electronics Division. All three are active products with ROHS3 compliance, meeting all primary equivalence criteria. BK/S506-1.6-R carries the broadest approval agency certifications (BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, VDE), making it suitable for applications requiring multi-regional compliance. Inventory availability is adequate across all three variants (1072, 1676, and 639 units respectively).

Eaton GMD Series (Enhanced Breaking Capacity):

The BK/GMD-1.6-R, BK1/GMD-1.6-R, and GMD-1.6-R offer identical electrical characteristics with elevated breaking capacity (100 A versus 35 A) and higher melting I²t (27 versus 21.7). These variants are suitable for applications requiring enhanced fault current handling. Approval agencies include CSA, PSE/JET, and UL. Inventory levels are strong (1804, 1008, and 1054 units respectively).

Cross-Manufacturer Alternatives:

The Littelfuse 021801.6MXP provides parametric equivalence with melting I²t of 23.35 and extended operating temperature range (-55°C to 125°C). Approval agencies include CCC, CE, CSA, K-MARK, PSE, SEMKO, UL, and VDE. Inventory is substantial (2622 units).

The SCHURTER 0034.3119 (FST 5x20 series) meets all primary equivalence criteria with melting I²t of 10.5, closely matching the original BK/S504-1.6A specification. Operating temperature range is -55°C to 125°C. Approval agencies include CCC, cURus, PSE/JET, and VDE. Inventory is highest among all alternatives (8955 units).

Compliance Considerations:

The original BK/S504-1.6A is RoHS non-compliant. All recommended substitutes are ROHS3 compliant, supporting transition to current regulatory requirements. REACH status is unaffected for all active alternatives.

Frequently Asked Questions (FAQ)

Q: Can BK/S506-1.6-R directly replace BK/S504-1.6A in existing designs?

A: Yes. BK/S506-1.6-R meets all primary equivalence criteria: 1.6 A current rating, 250 V AC voltage rating, cartridge glass fuse type, 5mm x 20mm package, and slow-blow response. The part is active and ROHS3 compliant. Physical dimensions and holder compatibility are identical.

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

A: Both series maintain identical current rating (1.6 A), voltage rating (250 V), package (5x20mm), and response time (slow blow). The GMD series provides higher breaking capacity (100 A versus 35 A) and higher melting I²t (27 versus 21.7). Selection depends on fault current requirements in the target application.

Q: Are Littelfuse and SCHURTER fuses mechanically compatible with Eaton fuse holders?

A: Yes. All substitute parts maintain the 5mm x 20mm cartridge glass form factor and require standard fuse holders. Physical dimensions are identical across manufacturers. Electrical characteristics are equivalent within specified parameters.

Q: Why does the original BK/S504-1.6A show RoHS non-compliance?

A: The BK/S504-1.6A is an obsolete product predating current RoHS3 requirements. All active substitute parts listed are ROHS3 compliant, supporting compliance with current environmental regulations.

Q: What is the significance of melting I²t variation among substitutes?

A: Melting I²t defines the thermal energy required to melt the fuse element. The original BK/S504-1.6A has melting I²t of 10. Substitutes range from 10.5 (SCHURTER 0034.3119) to 27 (Eaton GMD series). Higher values indicate slower thermal response. Selection should match the original thermal design envelope of the protected circuit.

Q: Which substitute offers the broadest international certification coverage?

A: BK/S506-1.6-R carries eight approval agencies: BSI, CCC, CSA, CURUS, IMQ, PSE/JET, SEMKO, and VDE. This breadth supports applications requiring multi-regional compliance.

Q: Is the SCHURTER 0034.3119 suitable for high-temperature applications?

A: The SCHURTER 0034.3119 specifies operating temperature range of -55°C to 125°C, matching the Littelfuse 021801.6MXP. The original BK/S504-1.6A does not specify operating temperature limits. For applications requiring extended temperature operation, SCHURTER or Littelfuse alternatives are appropriate.

Q: Can GMD series fuses be used in applications designed for 35 A breaking capacity?

A: Yes. The GMD series provides 100 A breaking capacity, which exceeds the 35 A requirement of the original design. Higher breaking capacity does not compromise performance in lower fault current environments. The GMD series is a direct electrical substitute with enhanced fault current handling capability.

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