Littelfuse 0324012.H Ceramic Fuse 12A 250VAC 125VDC Equivalent & Substitute Parts

Part Overview

The Littelfuse 0324012.H is a 12 A ceramic cartridge fuse rated for 250 V AC and 125 V DC operation with fast-blow response characteristics. This component is classified as obsolete, making equivalent and substitute parts necessary for ongoing system maintenance and new design implementations. The fuse is designed for through-hole mounting in 3AB/3AG form factor (1/4" x 1-1/4" axial) and provides 750 A AC and 10 kA DC breaking capacity at rated voltage.

Key Parameters

Parameter	Value
Current Rating	12 A
Voltage Rating - AC	250 V
Voltage Rating - DC	125 V
Fuse Type	Cartridge, Ceramic
Response Time	Fast Blow
Package / Case	3AB, 3AG, 1/4" x 1-1/4" (Axial)
Mounting Type	Through Hole
Breaking Capacity @ Rated Voltage	750 A AC, 10 kA DC
Melting I²t	570
Operating Temperature Range	-55°C ~ 125°C
DC Cold Resistance	0.0076 Ohms
Size / Dimension	0.275" Dia x 1.288" L (6.99 mm x 32.72 mm)

Substitute Part Grouping Explanation

Substitution of the Littelfuse 0324012.H is determined by strict equivalence across the following critical parameters:

Current Rating: 12 A (exact match required)
Voltage Rating - AC: 250 V (exact match required)
Voltage Rating - DC: 125 V (exact match required)
Fuse Type: Cartridge, Ceramic (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)
Breaking Capacity @ Rated Voltage: 750 A AC, 10 kA DC (exact match required)
Melting I²t: 570 (exact match required)
Operating Temperature Range: -55°C ~ 125°C (exact match required)
DC Cold Resistance: 0.0076 Ohms (exact match required)

All substitute parts listed below meet these criteria and are manufactured by Littelfuse Inc. within the 324 series.

Parameter Comparison

Parameter	0324012.H (Main)	0324012.HXP	0324012.MXP	0324012.VXP
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.
Current Rating (Amps)	12 A	12 A	12 A	12 A
Voltage Rating - AC	250 V	250 V	250 V	250 V
Voltage Rating - DC	125 V	125 V	125 V	125 V
Fuse Type	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic	Cartridge, Ceramic
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
Breaking Capacity @ Rated Voltage	750 A AC, 10 kA DC	750 A AC, 10 kA DC	750 A AC, 10 kA DC	750 A AC, 10 kA DC
Melting I²t	570	570	570	570
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C
DC Cold Resistance	0.0076 Ohms	0.0076 Ohms	0.0076 Ohms	0.0076 Ohms
Size / Dimension	0.275" Dia x 1.288" L (6.99 mm x 32.72 mm)	0.275" Dia x 1.288" L (6.99 mm x 32.72 mm)	0.275" Dia x 1.288" L (6.99 mm x 32.72 mm)	0.275" Dia x 1.288" L (6.99 mm x 32.72 mm)
Product Status	Obsolete	Active	Active	Active
Packaging	-	Bulk	Bulk	Bulk
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant
Approval Agency	CSA, METI, UL	CE, CSA, K-MARK, UL	CE, CSA, K-MARK, UL	CE, CSA, KC, PSE, UL

Engineering Selection Recommendations

The 0324012.H is obsolete and no longer in active production. All three substitute parts—0324012.HXP, 0324012.MXP, and 0324012.VXP—are active products with identical electrical and mechanical specifications.

For new designs and ongoing maintenance applications, 0324012.MXP is the primary recommendation due to highest inventory availability (10,781 pcs) and active product status. This part maintains full parametric equivalence while offering improved compliance posture with ROHS3 certification and REACH unaffected status.

0324012.HXP and 0324012.VXP are functionally equivalent alternatives with active status and ROHS3 compliance. Selection between these three active variants should be based on supply chain availability and regional certification requirements. All three parts carry CE, CSA, and UL approvals. 0324012.VXP includes additional PSE and KC certifications for expanded regional market support.

Frequently Asked Questions (FAQ)

Q: Can 0324012.HXP, 0324012.MXP, or 0324012.VXP be used as direct replacements for the obsolete 0324012.H?

A: Yes. All three substitute parts are direct parametric equivalents with identical current rating (12 A), voltage ratings (250 V AC / 125 V DC), fuse type (ceramic cartridge), response time (fast blow), package form factor (3AB/3AG, 1/4" x 1-1/4" axial), and electrical characteristics (breaking capacity, melting I²t, DC cold resistance). The primary difference is product status: the main part is obsolete while all substitutes are active.

Q: What is the difference between 0324012.HXP, 0324012.MXP, and 0324012.VXP?

A: These parts are electrically and mechanically identical. Differences exist only in packaging designation, inventory levels, and regional certifications. 0324012.MXP has the highest inventory availability. 0324012.VXP includes additional regional certifications (PSE, KC) beyond the standard CE, CSA, and UL approvals common to all three.

Q: Are there RoHS compliance differences between the main part and substitutes?

A: Yes. The 0324012.H is RoHS non-compliant. All three substitute parts (0324012.HXP, 0324012.MXP, 0324012.VXP) are ROHS3 compliant, making them suitable for applications requiring RoHS certification.

Q: Can these fuses be used in both AC and DC circuits?

A: Yes. All parts in this family are rated for dual-voltage operation: 250 V AC and 125 V DC. Circuit application must not exceed either voltage rating.

Q: What is the physical form factor, and will it fit existing through-hole mounting locations?

A: All parts use the 3AB/3AG cartridge form factor with dimensions 0.275" diameter x 1.288" length (6.99 mm x 32.72 mm). Through-hole mounting is standard for all variants. Physical compatibility is guaranteed across all four parts.

Q: What is the operating temperature range for these fuses?

A: All parts operate across -55°C to 125°C. This range applies to all four part numbers.

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