5ST 1.6 Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Bel Fuse Inc. 5ST 1.6 is a 1.6 A, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm form factor. This part is classified as obsolete, necessitating identification of active equivalent and substitute components that maintain electrical and mechanical compatibility. Substitute parts must match the current rating, voltage rating, response time classification, and physical dimensions to ensure proper circuit protection without modification to existing fuse holders.

Key Parameters

Parameter	Value
Current Rating	1.6 A
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	5mm x 20mm
Fuse Type	Cartridge, Glass
Mounting Type	Requires Holder
Operating Temperature Range	-55°C to 125°C

Substitute Part Grouping Explanation

Substitution eligibility is determined by strict equivalence across the following parameters:

Current Rating: 1.6 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Physical Dimensions: 5mm x 20mm (exact match required)
Fuse Type: Cartridge, Glass (exact match required)

Parts are grouped into two categories:

Direct Manufacturer Substitutes maintain all core electrical and mechanical parameters with active product status and current manufacturing availability.

Parametric Equivalents satisfy all functional requirements but may differ in breaking capacity, melting I²t, or DC cold resistance. These parts are electrically and mechanically interchangeable within the specified parameter set.

Parameter Comparison

Part Number	Manufacturer	Current (A)	Voltage (V AC)	Response Time	Package	Breaking Capacity @ Rated Voltage	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
5ST 1.6	Bel Fuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	6.9	0.04	Obsolete	Non-compliant
5ST 1.6-R	Bel Fuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	6.9	0.04	Active	ROHS3 Compliant
5ET 1.6-R	Bel Fuse Inc.	1.6	250	Slow Blow	5mm x 20mm	150 A	62	0.059	Active	ROHS3 Compliant
5TT 1.6-R	Bel Fuse Inc.	1.6	250	Slow Blow	5mm x 20mm	100 A	19.7	0.12	Active	ROHS3 Compliant
0034.3119	SCHURTER Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	10.5	—	Active	ROHS3 Compliant
021801.6HXP	Littelfuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	23.35	0.0336	Active	ROHS3 Compliant
021801.6MXBP	Littelfuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	23.35	0.0336	Active	ROHS3 Compliant
021801.6MXP	Littelfuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	23.35	0.0336	Active	ROHS3 Compliant
021801.6TXP	Littelfuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	23.35	0.0336	Active	ROHS3 Compliant
021801.6VXP	Littelfuse Inc.	1.6	250	Slow Blow	5mm x 20mm	35 A	23.35	0.0336	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: 5ST 1.6-R (Bel Fuse Inc.)

The 5ST 1.6-R is the direct active equivalent of the obsolete 5ST 1.6. It maintains identical electrical parameters (1.6 A, 250 V, 35 A breaking capacity, 6.9 melting I²t) and physical dimensions. This part is ROHS3 compliant and carries expanded certification coverage (CCC, CE, CSA, cURus, IMQ, SEMKO, VDE) compared to the original. Inventory availability is substantial at 8,726 units.

Secondary Recommendations: Littelfuse 218 Series (021801.6HXP, 021801.6MXBP, 021801.6MXP, 021801.6TXP, 021801.6VXP)

All Littelfuse 218 series parts meet the core electrical and mechanical requirements. These parts feature identical current, voltage, and response time ratings with matching 5mm x 20mm form factor. Melting I²t values (23.35) are higher than the original, providing slightly faster thermal response. All variants are ROHS3 compliant with comprehensive international certifications (CCC, CE, CSA, PSE, SEMKO, UL, VDE). Selection among these variants depends on specific certification requirements for the target application.

Alternative Recommendation: SCHURTER 0034.3119

The SCHURTER FST 5x20 series part 0034.3119 satisfies all functional requirements with 1.6 A, 250 V, slow-blow response, and 5mm x 20mm dimensions. Breaking capacity matches the original at 35 A. This part is ROHS3 compliant and carries PSE/JET, CCC, cURus, and VDE certifications. Physical dimensions are 5.20mm diameter (versus 5.10mm for Bel Fuse), representing a negligible tolerance variation within standard fuse holder specifications.

Parametric Alternatives: Bel Fuse 5ET 1.6-R and 5TT 1.6-R

The 5ET 1.6-R and 5TT 1.6-R are parametric equivalents with identical current, voltage, and response time ratings. These parts differ in breaking capacity (150 A and 100 A respectively) and melting I²t values (62 and 19.7). These characteristics indicate different thermal response profiles suitable for specific circuit protection requirements. Both are ROHS3 compliant and active products.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts directly in my existing fuse holder?

A: Yes. All listed substitute parts maintain the 5mm x 20mm cartridge form factor and are designed for standard 5x20mm fuse holders. Physical dimensions are within tolerance specifications for direct installation without holder modification.

Q: What is the difference between the Littelfuse 218 series variants (HXP, MXBP, MXP, TXP, VXP)?

A: All variants share identical electrical parameters (1.6 A, 250 V, slow-blow, 35 A breaking capacity, 23.35 melting I²t). Designations reflect different certification and packaging configurations. Selection should be based on the specific certifications required by your application or regional standards.

Q: How do the parametric equivalents (5ET 1.6-R, 5TT 1.6-R) differ from direct equivalents?

A: Parametric equivalents maintain the same current rating, voltage rating, and response time classification but differ in breaking capacity and melting I²t. The 5ET 1.6-R has higher breaking capacity (150 A) and melting I²t (62), while the 5TT 1.6-R has intermediate values (100 A breaking capacity, 19.7 melting I²t). These differences affect thermal response characteristics and are suitable for applications with different circuit protection requirements.

Q: Is the original 5ST 1.6 still available?

A: No. The 5ST 1.6 is classified as obsolete. The 5ST 1.6-R is the active replacement from the same manufacturer with identical electrical and mechanical specifications.

Q: What certifications should I verify for my application?

A: Verify that the selected substitute part carries the certifications required by your target market or application standard. All listed parts carry multiple international certifications (CE, CSA, UL, VDE, PSE, CCC). Confirm specific certification requirements with your design or compliance team.

Q: Are all substitute parts RoHS compliant?

A: Yes. All active substitute parts listed are ROHS3 compliant. The original 5ST 1.6 is RoHS non-compliant, making the transition to compliant alternatives necessary for new designs or regulatory compliance.

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