Littelfuse 20104000021 Glass Cartridge Fuse 400mA 250VAC 5x20mm Equivalent & Substitute Parts

Part Overview

The Littelfuse 20104000021 is a 400mA 250VAC glass cartridge fuse with 5mm x 20mm dimensions, designed for medium-blow response applications requiring holder mounting. This part carries an obsolete product status, making identification of functionally equivalent alternatives essential for ongoing system maintenance and component procurement. Substitute parts must maintain identical electrical ratings, mechanical dimensions, and safety certifications to ensure direct interchangeability in existing installations.

Substiute Parts

20104000021

Littelfuse Inc.In Stock: 120320104000021 Datasheet

Current PartRFQ

20104000021P

Littelfuse Inc.In Stock: 75220104000021P Datasheet

DirectRFQ

20104000001P

Littelfuse Inc.In Stock: 69820104000001P Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitute parts for the Littelfuse 20104000021 are qualified based on strict electrical and mechanical parameter matching. The following criteria determine substitution eligibility:

Critical Parameters for Substitution:

• Current Rating: 400 mA (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: Medium Blow (exact match required)
• Breaking Capacity @ Rated Voltage: 80A (exact match required)
• Melting I²t: 0.28 (exact match required)
• Approval Agency: cULus (exact match required)

All identified substitute parts meet these criteria and are manufactured by Littelfuse Inc. The primary distinction between the main part and substitutes is product status and packaging configuration.

Parameter Comparison

Engineering Selection Recommendations

The Littelfuse 20104000021 is classified as obsolete. Both substitute parts—20104000021P and 20104000001P—carry active product status and are available in bulk packaging configurations. Selection between substitute options should prioritize active product status and current inventory availability. Both substitutes maintain full compliance with cULus approval requirements and ROHS3 standards, ensuring regulatory continuity in applications requiring these certifications. The transition from the obsolete part number to either active substitute presents no electrical or mechanical compatibility concerns, as all critical parameters remain identical.

Frequently Asked Questions (FAQ)

Q: Can 20104000021P and 20104000001P be used interchangeably with 20104000021?

A: Yes. Both substitute parts match all critical electrical parameters (400mA, 250VAC, 80A breaking capacity, 0.28 I²t), mechanical dimensions (5mm x 20mm), response characteristics (medium blow), and safety certifications (cULus, ROHS3). Direct substitution is electrically and mechanically valid.

Q: What is the difference between the two substitute parts?

A: Both 20104000021P and 20104000001P are manufactured by Littelfuse Inc. and share identical electrical and mechanical specifications. The primary distinction is series designation (201P for both) and part number nomenclature. Both are active products available in bulk packaging.

Q: Why is the main part number 20104000021 marked as obsolete?

A: Product obsolescence reflects manufacturer discontinuation decisions. Active substitute parts with identical specifications are available to support ongoing system requirements and maintenance needs.

Q: Are there any packaging considerations when selecting a substitute?

A: The main part number 20104000021 carries unspecified packaging designation. Both substitute parts are supplied in bulk packaging. Verify bulk packaging compatibility with your procurement and assembly processes before selection.

Q: Do the substitute parts require the same holder as the original part?

A: Yes. All parts in this comparison require holder mounting. The 5mm x 20mm cartridge dimensions are identical across all three part numbers, ensuring mechanical compatibility with existing fuse holders.

Q: Are compliance certifications maintained across all parts?

A: Yes. All three parts carry cULus approval and ROHS3 compliance. The substitute parts also include REACH Unaffected status, providing additional regulatory documentation for international applications.