GDB-6.3A Equivalent & Substitute Parts Reference

Part Overview

The Eaton GDB-6.3A is a 6.3 A fast-blow glass cartridge fuse rated for 250 V AC/DC operation in a 5mm x 20mm package form factor. This fuse requires a compatible holder for installation and is designed for circuit protection applications requiring rapid response to overcurrent conditions. The part maintains active product status with 819 pieces in current inventory. Substitute parts are identified based on matching electrical ratings, mechanical dimensions, response characteristics, and approval certifications to ensure direct functional equivalence in circuit protection applications.

Key Parameters

Parameter	Value	Significance for Substitution
Current Rating	6.3 A	Must match exactly for circuit protection integrity
Voltage Rating (AC)	250 V	Must match or exceed for safe operation
Response Time	Fast Blow	Determines protection speed; must match application requirements
Package / Case	5mm x 20mm	Physical compatibility with holder and mounting space
Fuse Type	Cartridge, Glass	Determines holder compatibility and visual inspection capability
Breaking Capacity @ Rated Voltage	63 A (primary); 200 A (alternative)	Maximum fault current the fuse can safely interrupt
Mounting Type	Requires Holder	Installation method; all substitutes use same mounting approach

Substitute Part Grouping Explanation

Substitute parts for the GDB-6.3A are qualified based on the following mandatory matching criteria:

Primary Matching Parameters:

Current Rating: 6.3 A (exact match required)
Voltage Rating: 250 V AC minimum
Response Time: Fast Blow
Package Dimensions: 5mm x 20mm
Fuse Type: Cartridge, Glass
Mounting: Requires Holder

Secondary Considerations:

Breaking Capacity: Minimum 63 A at rated voltage (200 A variants acceptable for higher fault current applications)
Melting I²t: Range 40.8 to 69 (indicates thermal response characteristics)
Approval Agencies: VDE, UL, CSA, cULus, or equivalent recognized certifications
RoHS Compliance: ROHS3 Compliant status preferred for environmental standards

All listed substitute parts meet or exceed these criteria. Variations in breaking capacity, melting I²t, and approval certifications reflect different application environments and regulatory jurisdictions but do not affect basic circuit protection function when electrical and mechanical parameters align.

Parameter Comparison

Manufacturer Part Number	Manufacturer	Series	Current (A)	Voltage (V AC)	Response	Package	Breaking Capacity (A)	Melting I²t	Approval Agencies
GDB-6.3A	Eaton	GDB	6.3	250	Fast Blow	5x20mm	63	69	VDE, UR
BK/GDB-6.3A	Eaton	GDB	6.3	250	Fast Blow	5x20mm	63	69	UL, VDE
BK/S500-6.3-R	Eaton	S500	6.3	250	Fast Blow	5x20mm	63	69	BSI, CCC, CSA, cULus, IMQ, SEMKO, VDE
BK1/S500-6.3-R	Eaton	S500	6.3	250	Fast Blow	5x20mm	63	69	BSI, CCC, CSA, cULus, IMQ, SEMKO, VDE
S500-6.3-R	Eaton	S500	6.3	250	Fast Blow	5x20mm	63	69	BSI, CCC, CSA, cURus, IMQ, SEMKO, VDE
0034.1524	SCHURTER	FSF 5x20	6.3	250	Fast Blow	5x20mm	63	53.2	CCC, cURus, PSE/JET, VDE
0034.3885	SCHURTER	FSK 5x20	6.3	250	Fast Blow	5x20mm	200	40.8	cULus
021706.3HXP	Littelfuse	217	6.3	250	Fast Blow	5x20mm	63	62.465	BSI, CCC, CE, CSA, KC, PSE, SEMKO, UR, VDE
021706.3MXP	Littelfuse	217	6.3	250	Fast Blow	5x20mm	63	62.465	BSI, CCC, CE, CSA, KC, PSE, SEMKO, UR, VDE
021706.3TXP	Littelfuse	217	6.3	250	Fast Blow	5x20mm	63	62.465	BSI, CCC, CE, CSA, KC, PSE, SEMKO, UR, VDE
FSC-6.3A	OptiFuse	FSC	6.3	250	Fast Blow	5x20mm	200	Not specified	cULus, UL 248

Engineering Selection Recommendations

Eaton GDB Series (Primary Manufacturer Match): BK/GDB-6.3A, BK/S500-6.3-R, BK1/S500-6.3-R, and S500-6.3-R maintain active product status from the original manufacturer. These parts carry expanded approval certifications including UL, CSA, and cULus, supporting North American and international regulatory compliance. Inventory availability ranges from 837 to 8391 pieces, ensuring supply continuity.

Littelfuse 217 Series (Broad Certification Coverage): 021706.3HXP, 021706.3MXP, and 021706.3TXP provide comprehensive international approvals (BSI, CCC, CE, CSA, KC, PSE, SEMKO, UR, VDE) and extended operating temperature range (-55°C to 125°C). These variants support applications requiring multi-regional compliance documentation. Melting I²t values (62.465) closely align with the GDB-6.3A specification (69).

SCHURTER FSF and FSK Series (Specialized Applications): 0034.1524 (FSF 5x20) offers broad certifications with operating temperature range -55°C to 125°C and melting I²t of 53.2. The 0034.3885 (FSK 5x20) provides 200 A breaking capacity for high fault current environments, with cULus certification and operating range -40°C to 85°C.

OptiFuse FSC Series (High Breaking Capacity): FSC-6.3A delivers 200 A breaking capacity with cULus and UL 248 certifications, suitable for applications with elevated fault current requirements. Operating temperature range -55°C to 90°C supports diverse thermal environments.

Selection Basis: Choose substitutes based on required approval certifications for your target market, operating temperature range, and breaking capacity requirements. All listed parts maintain identical current rating, voltage rating, response time, and physical dimensions, ensuring mechanical and electrical compatibility with the original GDB-6.3A application.

Frequently Asked Questions (FAQ)

Q: Can I substitute a 6.3 A fuse with a different current rating? A: No. The current rating must match exactly. Substituting with a higher rating reduces circuit protection; a lower rating causes nuisance trips. The 6.3 A rating is specific to the circuit design and load characteristics.

Q: What does "Fast Blow" response mean, and can I use a "Slow Blow" fuse instead? A: Fast Blow fuses respond rapidly to overcurrent, typically within milliseconds. Slow Blow fuses tolerate temporary inrush currents. These are not interchangeable. Use only Fast Blow substitutes for GDB-6.3A applications.

Q: Does breaking capacity matter when selecting a substitute? A: Yes. Breaking capacity indicates the maximum fault current the fuse can safely interrupt. The GDB-6.3A specifies 63 A; substitutes with 200 A breaking capacity provide additional safety margin in high fault current environments but remain compatible. Do not use fuses with breaking capacity below 63 A.

Q: Are all 5mm x 20mm fuses compatible with my holder? A: Physical dimensions alone do not guarantee compatibility. Verify that the substitute fuse type (Cartridge, Glass) and mounting method (Requires Holder) match your equipment. Consult your holder documentation for approved part numbers.

Q: What is melting I²t, and why do values vary among substitutes? A: Melting I²t quantifies the thermal energy required to melt the fuse element, affecting response speed and thermal characteristics. Variations (40.8 to 69) reflect different fuse designs. All listed substitutes maintain Fast Blow response; I²t differences do not affect basic circuit protection function when current and voltage ratings match.

Q: Which substitute has the broadest international approvals? A: Littelfuse 217 series (021706.3HXP, 021706.3MXP, 021706.3TXP) and Eaton S500 series carry approvals from BSI, CCC, CSA, cULus, IMQ, SEMKO, UR, and VDE, supporting North American, European, and Asian regulatory requirements.

Q: Can I use a substitute with a different operating temperature range? A: Operating temperature range indicates the environment where the fuse functions reliably. If your application operates within the substitute's specified range, it is acceptable. Verify that the substitute's range encompasses your installation environment.

Q: Is RoHS3 compliance required for my application? A: RoHS3 compliance is mandatory for products sold in the European Union and many other jurisdictions. Most listed substitutes are ROHS3 Compliant. Verify compliance requirements for your target market before final selection.

Q: What is the difference between UL, cULus, and UR certifications? A: UL indicates Underwriters Laboratories certification (North America). cULus indicates CSA (Canadian Standards Association) and UL joint certification. UR indicates Underwriters' Laboratories of Japan. These certifications confirm the fuse meets specific regional safety standards. Select substitutes with certifications matching your regulatory requirements.

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