Littelfuse 031501.8H Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 031501.8H is a 1.8 A, 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 production alternatives with identical electrical and mechanical specifications are available from the same manufacturer series.

Key Parameters

Parameter	Specification
Current Rating	1.8 A
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	100 A
Melting I²t	58
Operating Temperature Range	-55°C to 125°C
Size / Dimension	0.275" Dia x 1.275" L (6.99mm x 32.39mm)
DC Cold Resistance	0.14 Ohms
Mounting Type	Through Hole

Substitute Part Grouping Explanation

Substitute parts for the 031501.8H are determined by strict equivalence across all critical electrical and mechanical parameters: current rating (1.8 A), voltage rating (250 V AC), response time (slow blow), package format (3AB/3AG), physical dimensions (0.275" Dia x 1.275" L), breaking capacity (100 A), and melting I²t value (58). All substitute parts maintain identical specifications in these categories, ensuring direct functional interchangeability in circuit protection applications.

The three active substitute parts—031501.8HXP, 031501.8MXP, and 031501.8VXP—differ only in packaging configuration (bulk) and compliance certifications, not in electrical or mechanical performance.

Parameter Comparison

Parameter	031501.8H (Main)	031501.8HXP	031501.8MXP	031501.8VXP
Current Rating (Amps)	1.8 A	1.8 A	1.8 A	1.8 A
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	100 A	100 A	100 A	100 A
Melting I²t	58	58	58	58
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	0.14 Ohms	0.141 Ohms	0.141 Ohms	0.141 Ohms
Product Status	Obsolete	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, METI, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL	CE, CSA, PSE, UL

Engineering Selection Recommendations

All three substitute parts (031501.8HXP, 031501.8MXP, 031501.8VXP) provide direct electrical and mechanical equivalence to the obsolete 031501.8H. Selection among these active alternatives should be based on:

Product Status: All substitutes are in active production, ensuring long-term availability and supply chain continuity compared to the obsolete main part.

Compliance Requirements: The substitute parts carry ROHS3 compliance and expanded regulatory certifications (CE, CSA, PSE, UL) compared to the non-compliant main part. Applications requiring RoHS3 compliance or international market distribution should use one of the substitute parts.

Regulatory Certifications: The main part holds CSA, METI, and UL approvals. Substitute parts maintain UL and CSA certifications while adding CE and PSE approvals, providing broader regulatory coverage for global applications.

DC Cold Resistance: Substitute parts exhibit 0.141 Ohms versus 0.14 Ohms in the main part. This minor variation (0.7% difference) is within normal manufacturing tolerance and does not affect functional performance in circuit protection applications.

Frequently Asked Questions (FAQ)

Q: Can 031501.8HXP, 031501.8MXP, and 031501.8VXP be used interchangeably with 031501.8H?

A: Yes. All three substitute parts maintain identical electrical specifications (1.8 A, 250 V AC, slow-blow response), mechanical dimensions (0.275" Dia x 1.275" L), and performance characteristics (100 A breaking capacity, 58 melting I²t). Direct substitution is functionally equivalent.

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

A: The substitute parts are electrically and mechanically identical. Differences exist only in packaging configuration (all are bulk packaged) and regulatory certifications. All three are active production parts with ROHS3 compliance and expanded approval agencies (CE, CSA, PSE, UL).

Q: Why is the main part 031501.8H classified as obsolete?

A: The main part is no longer in active production. The substitute parts represent the current active alternatives from Littelfuse for this specification class.

Q: Are there any compatibility concerns when replacing 031501.8H with a substitute part?

A: No compatibility concerns exist. The substitute parts are designed for the same 3AB/3AG through-hole mounting format and operate across the identical temperature range (-55°C to 125°C). Physical dimensions and electrical performance are equivalent.

Q: Does the slight difference in DC cold resistance (0.14 vs 0.141 Ohms) affect circuit performance?

A: No. The 0.7% difference in DC cold resistance is within normal manufacturing tolerance for fuses and does not impact circuit protection performance or thermal characteristics in practical applications.

Q: Which substitute part should be selected for new designs?

A: Any of the three substitute parts (031501.8HXP, 031501.8MXP, 031501.8VXP) is suitable for new designs. Selection may depend on packaging preferences, regional regulatory requirements, or supplier availability. All maintain identical electrical and mechanical specifications.

Request Quote (Ships tomorrow)

Part Number

Quantity

Company

Contact Name

E-mail

Message