5ST 800 Equivalent & Substitute Parts

Part Overview

The 5ST 800 is an 800 mA, 250 V AC/DC slow-blow glass cartridge fuse in 5mm x 20mm package format, manufactured by Bel Fuse Inc. This component is classified as obsolete, requiring identification of active equivalent alternatives for ongoing system support and procurement. Substitute parts must maintain identical electrical ratings, mechanical dimensions, and functional characteristics to ensure direct compatibility in existing fuse holder assemblies.

Key Parameters

Parameter	Specification
Current Rating	800 mA
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Slow Blow
Package / Case	5mm x 20mm
Breaking Capacity @ Rated Voltage	35A
Operating Temperature Range	-55°C ~ 125°C
Mounting Type	Requires Holder

Substitute Part Grouping Explanation

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

Current Rating: 800 mA (exact match required)
Voltage Rating: 250 V AC (exact match required)
Response Time: Slow Blow (exact match required)
Package Dimensions: 5mm x 20mm (exact match required)
Breaking Capacity: 35A (exact match required)
Operating Temperature: -55°C ~ 125°C (exact match required)

All substitute parts listed maintain these core electrical and mechanical specifications. Variations in secondary parameters such as melting I²t, DC cold resistance, and approval agencies do not affect functional interchangeability within the specified operating envelope.

Parameter Comparison

Part Number	Manufacturer	Current Rating	Voltage (AC)	Response Time	Package	Breaking Capacity	Melting I²t	DC Cold Resistance (Ω)	Product Status	RoHS Status
5ST 800	Bel Fuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	1.6	0.15	Obsolete	RoHS non-compliant
5ST 800-R	Bel Fuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	1.6	0.15	Active	ROHS3 Compliant
0034.3116	SCHURTER Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.85	—	Active	ROHS3 Compliant
0218.800MXBP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.37	0.0813	Active	ROHS3 Compliant
0218.800MXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.37	0.0813	Active	ROHS3 Compliant
0218.800TXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.37	0.0813	Active	ROHS3 Compliant
0218.800VXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.37	0.0813	Active	ROHS3 Compliant
0213.800MXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	9.42	0.1635	Active	ROHS3 Compliant
0218.800HXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	3.37	0.0813	Active	ROHS3 Compliant
0239.800HXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	7.565	0.4155	Active	ROHS3 Compliant
0239.800TXP	Littelfuse Inc.	800 mA	250 V	Slow Blow	5x20mm	35A	7.565	0.4155	Active	ROHS3 Compliant

Engineering Selection Recommendations

Primary Recommendation: 5ST 800-R

The 5ST 800-R is the direct active equivalent from the original manufacturer, Bel Fuse Inc. It maintains identical electrical and mechanical specifications to the obsolete 5ST 800 while achieving ROHS3 compliance. This part is the preferred choice for direct replacement in existing designs.

Secondary Recommendations: Littelfuse 218 Series (0218.800MXBP, 0218.800MXP, 0218.800TXP, 0218.800VXP, 0218.800HXP)

These parts are functionally equivalent across all critical parameters. All are active products with ROHS3 compliance and comprehensive approval certifications (CCC, CE, CSA, SEMKO, UL, VDE). The 218 series variants differ in approval agency coverage; selection should align with regional regulatory requirements.

Alternative: SCHURTER 0034.3116

This part meets all electrical and mechanical requirements with active product status and ROHS3 compliance. Approval coverage is limited to CCC, cURus, and VDE. Use when SCHURTER supply chain preference or specific regional certifications are required.

Extended Alternatives: Littelfuse 213 and 239 Series

The 0213.800MXP and 0239.800HXP/0239.800TXP parts maintain core electrical ratings but exhibit higher melting I²t values (9.42 and 7.565 respectively, compared to 1.6 for the original). These represent slower response characteristics and should be selected only when system thermal design specifically accommodates extended response times.

Frequently Asked Questions (FAQ)

Q: Can I use any of these substitute parts directly in place of the 5ST 800?

A: Yes. All listed parts maintain identical current rating (800 mA), voltage rating (250 V AC), response time (slow blow), package dimensions (5mm x 20mm), and breaking capacity (35A). Direct mechanical and electrical compatibility is assured within the specified operating temperature range (-55°C to 125°C).

Q: What is the difference between the Littelfuse 218, 213, and 239 series fuses?

A: The primary difference is melting I²t, which determines thermal response speed. The 218 series (I²t = 3.37) provides faster response than the original 5ST 800 (I²t = 1.6). The 213 series (I²t = 9.42) and 239 series (I²t = 7.565) provide slower response. Selection depends on system thermal design requirements. All maintain the same current and voltage ratings.

Q: Is the 5ST 800-R the best choice for replacement?

A: The 5ST 800-R is the recommended primary choice because it is the direct active equivalent from the original manufacturer with identical specifications and ROHS3 compliance. It eliminates any design validation concerns associated with cross-manufacturer substitution.

Q: Do all substitute parts have the same approval certifications?

A: No. Approval agency coverage varies by part. The 5ST 800-R includes CCC, CE, CSA, cURus, IMQ, SEMKO, and VDE. Littelfuse 218 series parts include CCC, CE, CSA, K-MARK, SEMKO, UL, and VDE. The SCHURTER 0034.3116 includes CCC, cURus, and VDE. Select based on regional regulatory requirements for your application.

Q: What does RoHS3 compliance mean for my application?

A: ROHS3 compliance indicates the part meets Restriction of Hazardous Substances Directive requirements, restricting lead, cadmium, mercury, and other hazardous materials. The original 5ST 800 is RoHS non-compliant. All active substitutes listed are ROHS3 compliant, making them suitable for applications with environmental or regulatory RoHS requirements.

Q: Can I mix different substitute parts in the same system?

A: Yes, provided all parts are installed in identical fuse holder assemblies and the system design accommodates the range of melting I²t values present. For consistency and simplified maintenance, using a single part number across an application is recommended.

Q: What is DC cold resistance and why does it vary?

A: DC cold resistance is the measured resistance of the fuse element at room temperature. Variations reflect different internal element designs among manufacturers. All listed parts maintain functional equivalence; resistance variations do not affect circuit protection performance within the specified electrical ratings.

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