Littelfuse 0318004.H Glass Cartridge Fuse Equivalent & Substitute Parts

Part Overview

The Littelfuse 0318004.H is a 4 A 250 V AC/DC glass cartridge fuse with fast-blow response characteristics, designed for through-hole mounting in 3AB/3AG package format (1/4" x 1-1/4" axial). This part is classified as obsolete, making equivalent substitute parts necessary for ongoing circuit protection applications. Active alternatives are available from the same manufacturer with identical electrical specifications and improved compliance status.

Key Parameters

Parameter	Value
Current Rating	4 A
Voltage Rating (AC)	250 V
Fuse Type	Cartridge, Glass
Response Time	Fast Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)
Melting I²t	28.5
DC Cold Resistance	0.0291 Ohms

Substitute Part Grouping Explanation

Substitution of the 0318004.H is based on strict equivalence across the following critical parameters:

Current Rating: 4 A (exact match required)
Voltage Rating: 250 V AC (exact match required)
Fuse Type: Cartridge, Glass (exact match required)
Response Time: Fast Blow (exact match required)
Package / Case: 3AB, 3AG, 1/4" x 1-1/4" (Axial) (exact match required)
Mounting Type: Through Hole (exact match required)
Series: 318 (manufacturer series consistency)

All substitute parts listed below meet these criteria without deviation. Substitution is direct and does not require circuit redesign or mechanical modification.

Parameter Comparison

Parameter	0318004.H (Main)	0318004.HXP	0318004.MXP	0318004.VXP
Current Rating (Amps)	4 A	4 A	4 A	4 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Fuse Type	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass	Cartridge, Glass
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast 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)
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole
Size / Dimension	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)	0.275" Dia x 1.288" L (6.99mm x 32.72mm)
Melting I²t	28.5	28.5	28.5	28.5
DC Cold Resistance	0.0291 Ohms	0.0293 Ohms	0.0293 Ohms	0.0293 Ohms
Breaking Capacity @ Rated Voltage	35 A	200 A	200 A	200 A
Product Status	Obsolete	Active	Active	Active
Approval Agency	CSA, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL	CE, CSA, KC, PSE, UL
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Operating Temperature	Not specified	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C

Engineering Selection Recommendations

Direct Substitution: Parts 0318004.HXP, 0318004.MXP, and 0318004.VXP are direct functional equivalents to 0318004.H. All three substitute parts are active products with identical electrical and mechanical specifications.

Compliance Advantage: The substitute parts offer improved regulatory compliance compared to the obsolete main part. All three alternatives are ROHS3 compliant and carry expanded approval certifications (CE, CSA, KC, PSE, UL) versus the main part's CSA and UL certifications only.

Breaking Capacity: Substitute parts feature a breaking capacity of 200 A at rated voltage, compared to 35 A for the main part. This represents an enhanced safety margin without affecting circuit protection function.

Packaging: All substitute parts are supplied in bulk packaging, whereas the main part was supplied in standard packaging. This distinction affects procurement and inventory management only.

Selection Basis: Choose any of the three substitute parts based on availability and procurement lead time. No technical differentiation exists between 0318004.HXP, 0318004.MXP, and 0318004.VXP for circuit protection applications.

Frequently Asked Questions (FAQ)

Q: Can 0318004.HXP, 0318004.MXP, or 0318004.VXP be used as direct replacements for 0318004.H?

A: Yes. All three parts are direct substitutes with identical current rating (4 A), voltage rating (250 V AC), fuse type (cartridge, glass), response time (fast blow), package format (3AB, 3AG), and physical dimensions. No circuit modification is required.

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

A: 0318004.HXP, 0318004.MXP, and 0318004.VXP are functionally identical. They differ only in inventory availability and internal manufacturing designations. Selection should be based on procurement availability.

Q: Why does the main part show a lower breaking capacity (35 A) than the substitutes (200 A)?

A: The breaking capacity specification reflects the maximum current the fuse can safely interrupt without rupturing the glass envelope. The substitute parts have enhanced breaking capacity, providing greater safety margin. This does not affect the 4 A protection threshold.

Q: Are the substitute parts RoHS compliant?

A: Yes. All three substitute parts (0318004.HXP, 0318004.MXP, 0318004.VXP) are ROHS3 compliant. The main part 0318004.H is RoHS non-compliant.

Q: What certifications do the substitute parts carry?

A: All three substitute parts carry CE, CSA, KC, PSE, and UL certifications. The main part carries CSA and UL certifications only.

Q: Can these fuses be used in applications with operating temperatures below 0°C or above 85°C?

A: The substitute parts are rated for -55°C to 125°C operating temperature. Confirm application requirements fall within this range before selection.

Q: Is there any difference in DC cold resistance between the main part and substitutes?

A: The main part has 0.0291 Ohms DC cold resistance, while all three substitutes have 0.0293 Ohms. This negligible difference (0.0002 Ohms) does not affect circuit performance.

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