Littelfuse 0315.800H Glass Cartridge Fuse - Equivalent & Substitute Parts

Part Overview

The Littelfuse 0315.800H is an 800 mA, 250 V AC/DC slow-blow glass cartridge fuse in the 3AB/3AG package format (1/4" x 1-1/4" axial). This component is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications. Active alternatives from the same manufacturer maintain identical electrical and mechanical specifications while offering improved compliance status and current product support.

Key Parameters

Parameter	Value
Current Rating	800 mA
Voltage Rating (AC)	250 V
Response Time	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Fuse Type	Cartridge, Glass
Breaking Capacity @ Rated Voltage	35 A
Melting I²t	8
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.275" Dia x 1.275" L (6.99mm x 32.39mm)
DC Cold Resistance	0.55 Ohms

Substitute Part Grouping Explanation

Substitution eligibility for the 0315.800H 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 / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Breaking Capacity: 35 A (exact match required)
Melting I²t: 8 (exact match required)
Operating Temperature: -55°C ~ 125°C (exact match required)
Physical Dimensions: 0.275" Dia x 1.275" L (exact match required)

All three substitute parts (0315.800HXP, 0315.800MXP, 0315.800VXP) meet these criteria and are direct functional equivalents of the 0315.800H.

Parameter Comparison

Parameter	0315.800H (Main)	0315.800HXP	0315.800MXP	0315.800VXP
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Current Rating (Amps)	800 mA	800 mA	800 mA	800 mA
Voltage Rating - AC	250 V	250 V	250 V	250 V
Response Time	Slow Blow	Slow Blow	Slow Blow	Slow Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Breaking Capacity @ Rated Voltage	35 A	35 A	35 A	35 A
Melting I²t	8	8	8	8
Operating Temperature	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
Size / Dimension	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)	0.275" Dia x 1.275" L (6.99mm x 32.39mm)
DC Cold Resistance	0.55 Ohms	0.554 Ohms	0.554 Ohms	0.554 Ohms
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, UL	CE, CSA, UL	CE, CSA, UL	CE, CSA, UL

Engineering Selection Recommendations

All three substitute parts (0315.800HXP, 0315.800MXP, 0315.800VXP) are functionally equivalent to the 0315.800H and provide direct replacement capability. Selection among the three active alternatives should be based on:

Product Status: The 0315.800H is obsolete. All three substitutes are active products with ongoing manufacturer support and availability.

Compliance: The 0315.800H is RoHS non-compliant. All three substitutes are ROHS3 compliant, meeting current environmental and regulatory requirements. All substitutes carry CE certification in addition to CSA and UL approvals held by the original part.

Electrical Performance: DC cold resistance values for the substitutes (0.554 Ohms) are negligibly higher than the main part (0.55 Ohms) and remain within acceptable tolerance for this component class.

Packaging: All substitutes are supplied in bulk packaging, consistent with standard distribution formats for active components.

Frequently Asked Questions (FAQ)

Q: Can the 0315.800HXP, 0315.800MXP, or 0315.800VXP be used as direct replacements for the 0315.800H?

A: Yes. All three parts are direct functional equivalents. They maintain identical current rating (800 mA), voltage rating (250 V AC), response time (slow blow), package format (3AB/3AG), physical dimensions (0.275" Dia x 1.275" L), and electrical performance characteristics. The DC cold resistance difference (0.554 Ohms vs. 0.55 Ohms) is negligible for circuit protection applications.

Q: Why are there three substitute part numbers for a single obsolete part?

A: The three substitutes (0315.800HXP, 0315.800MXP, 0315.800VXP) are parametrically equivalent variants from Littelfuse. They share identical electrical and mechanical specifications but may differ in internal construction, manufacturing process, or certification scope. All three are active products suitable for replacement applications.

Q: What is the difference between the 0315.800H and its substitutes in terms of compliance?

A: The 0315.800H is RoHS non-compliant and carries CSA and UL approvals. All three substitutes are ROHS3 compliant and carry CE, CSA, and UL approvals, meeting modern environmental and regulatory standards.

Q: Are the physical dimensions identical across all parts?

A: Yes. The 0315.800H and all three substitutes share identical dimensions: 0.275" diameter x 1.275" length (6.99mm x 32.39mm). They are mechanically interchangeable in 3AB/3AG package footprints.

Q: Can I mix substitute parts in the same circuit or application?

A: Yes. All three substitutes are parametrically equivalent and can be used interchangeably. Selection can be based on availability, packaging preference, or supply chain considerations.

Q: What is the significance of the DC cold resistance specification?

A: DC cold resistance (0.55 Ohms for the main part, 0.554 Ohms for substitutes) represents the fuse element resistance at room temperature. The negligible difference does not affect circuit protection performance or thermal characteristics in typical applications.

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