5TT 400 Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The 5TT 400 is a 400 mA, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm form factor, manufactured by Bel Fuse Inc. This component is classified as obsolete, requiring identification of active equivalent alternatives for new designs and ongoing maintenance applications. The 5TT 400 series fuses are used in circuit protection applications where controlled current interruption and thermal response characteristics are critical to system reliability.

Substiute Parts

5TT 400

Bel Fuse Inc.In Stock: 8115TT 400 Datasheet

Current PartRFQ

5TT 400-R

Bel Fuse Inc.In Stock: 147205TT 400-R Datasheet

DirectRFQ

5ST 400-R

Bel Fuse Inc.In Stock: 1125715ST 400-R Datasheet

Parametric EquivalentRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution for the 5TT 400 is determined by strict equivalence across the following critical parameters:

• Current Rating: 400 mA (exact match required)
• Voltage Rating (AC): 250 V (exact match required)
• Fuse Type: Cartridge, Glass (exact match required)
• Response Time: Slow Blow (exact match required)
• Package / Case: 5mm x 20mm (exact match required)
• Mounting Type: Requires Holder (exact match required)

Two substitute parts meet these criteria: the 5TT 400-R (direct manufacturer upgrade) and the 5ST 400-R (parametric equivalent from the same manufacturer). Both maintain identical electrical and mechanical specifications while offering improved product status and compliance certifications.

Parameter Comparison

Engineering Selection Recommendations

The 5TT 400-R is the direct manufacturer upgrade path, maintaining identical electrical performance (100 A breaking capacity) while transitioning from obsolete to active product status. This part carries ROHS3 compliance and expanded certification coverage (cULus addition), making it suitable for applications requiring current regulatory alignment.

The 5ST 400-R provides an alternative from the same manufacturer with equivalent electrical and mechanical characteristics. This part features the broadest certification scope (CCC, CE, CSA, cURus, IMQ, SEMKO, VDE) and ROHS3 compliance. The 5ST 400-R exhibits a reduced breaking capacity of 35 A compared to the 5TT series' 100 A rating; this difference must be evaluated against specific circuit protection requirements.

Both substitutes are available in active production with substantial inventory levels, ensuring supply chain continuity for replacement and new design applications.

Frequently Asked Questions (FAQ)

Q: Can the 5TT 400-R directly replace the 5TT 400 in existing designs?

A: Yes. The 5TT 400-R maintains identical current rating (400 mA), voltage rating (250 V AC), fuse type (cartridge, glass), response time (slow blow), package dimensions (5mm x 20mm), and breaking capacity (100 A). No circuit modifications are required.

Q: What is the difference between the 5TT 400-R and 5ST 400-R?

A: Both parts share identical current, voltage, fuse type, response time, and package specifications. The primary difference is breaking capacity: 5TT 400-R provides 100 A breaking capacity, while 5ST 400-R provides 35 A. The 5ST 400-R also carries a broader range of international certifications (CCC, IMQ, SEMKO, VDE in addition to CE, CSA, cURus).

Q: Are both substitute parts RoHS compliant?

A: Yes. Both the 5TT 400-R and 5ST 400-R are ROHS3 compliant, addressing the RoHS non-compliance status of the original 5TT 400.

Q: Does the reduced breaking capacity of the 5ST 400-R affect compatibility?

A: Breaking capacity determines the maximum fault current the fuse can safely interrupt. The 5ST 400-R's 35 A breaking capacity is suitable for circuits where maximum fault current does not exceed this threshold. Applications requiring 100 A breaking capacity must use the 5TT 400-R.

Q: What certifications apply to each substitute part?

A: The 5TT 400-R carries CE, CSA, and cULus certifications. The 5ST 400-R carries CCC, CE, CSA, cURus, IMQ, SEMKO, and VDE certifications. Selection should align with regional regulatory requirements for the target application.

Q: Are these parts available in the same packaging format?

A: Both substitute parts are supplied in bulk packaging, consistent with the original 5TT 400 series. All three parts require a fuse holder for installation; no holder is included with the fuse cartridge itself.