Littelfuse 0313012.H Glass Cartridge Fuse 12A 32VAC Equivalent & Substitute Parts

Part Overview

The Littelfuse 0313012.H is a 12 A, 32 V AC/DC slow-blow glass cartridge fuse in 3AB/3AG package format (1/4" x 1-1/4"). This component is classified as obsolete, though functionally equivalent active alternatives are available from both Littelfuse and Eaton. Substitute parts are necessary due to the obsolete status of the original part number, requiring selection from active product lines that maintain identical electrical and mechanical specifications.

Key Parameters

Parameter	Value
Current Rating	12 A
Voltage Rating (AC)	32 V
Response Time	Slow Blow
Fuse Type	Cartridge, Glass
Package / Case	3AB, 3AG, 1/4" x 1-1/4"
Size / Dimension	0.250" Dia x 1.250" L (6.35mm x 31.75mm)
Breaking Capacity @ Rated Voltage	300 A
Melting I²t	1200
Mounting Type	Requires Holder

Substitute Part Grouping Explanation

Substitute parts for the 0313012.H are grouped into two categories based on manufacturer and product status:

Littelfuse Active Equivalents: Parts 0313012.HXP, 0313012.MXP, and 0313012.VXP are direct parametric equivalents manufactured by Littelfuse. These parts maintain identical electrical specifications (12 A, 32 V AC, slow-blow response, 300 A breaking capacity, 1200 I²t) and mechanical form factor (3AB/3AG, 1/4" x 1-1/4"). All three are active products with ROHS3 compliance.

Eaton Cross-Manufacturer Equivalents: Parts BK/MDL-12-R and BK/MDQ-12 are manufactured by Eaton - Electronics Division and provide parametric equivalence across all critical electrical parameters (12 A, 32 V AC, slow-blow response, 3AB/3AG package, identical dimensions). These parts are active and ROHS3 compliant (BK/MDL-12-R) or non-compliant (BK/MDQ-12).

Substitution is valid when the following parameters match the original part: current rating (12 A), voltage rating (32 V AC), response time (slow-blow), fuse type (cartridge glass), package format (3AB/3AG), and physical dimensions (0.250" Dia x 1.250" L).

Parameter Comparison

Part Number	Manufacturer	Current Rating (A)	Voltage Rating (V AC)	Response Time	Package / Case	Size (Dia x L)	Breaking Capacity (A)	Melting I²t	Product Status	RoHS Status
0313012.H	Littelfuse Inc.	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	300	1200	Obsolete	RoHS non-compliant
0313012.HXP	Littelfuse Inc.	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	300	1200	Active	ROHS3 Compliant
0313012.MXP	Littelfuse Inc.	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	300	1200	Active	ROHS3 Compliant
0313012.VXP	Littelfuse Inc.	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	300	1200	Active	ROHS3 Compliant
BK/MDL-12-R	Eaton - Electronics Division	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	—	—	Active	ROHS3 Compliant
BK/MDQ-12	Eaton - Electronics Division	12	32	Slow Blow	3AB, 3AG, 1/4" x 1-1/4"	0.250" x 1.250"	—	—	Active	RoHS non-compliant

Engineering Selection Recommendations

Primary Selection: Littelfuse 0313012.HXP, 0313012.MXP, or 0313012.VXP are recommended as direct replacements. All three are active products with identical electrical and mechanical specifications to the obsolete 0313012.H. These parts carry ROHS3 compliance and are manufactured by the original equipment supplier, ensuring design continuity.

Cross-Manufacturer Alternative: Eaton BK/MDL-12-R provides parametric equivalence with ROHS3 compliance and is suitable for applications where cross-manufacturer sourcing is acceptable. Eaton BK/MDQ-12 is also parametrically equivalent but carries RoHS non-compliance status, matching the compliance profile of the original 0313012.H.

Selection between Littelfuse and Eaton alternatives depends on supply chain requirements, inventory availability, and compliance mandates. All substitute parts maintain the same current rating, voltage rating, response time, package format, and physical dimensions required for direct mechanical and electrical compatibility.

Frequently Asked Questions (FAQ)

Q: Can 0313012.HXP, 0313012.MXP, and 0313012.VXP be used interchangeably? A: Yes. All three Littelfuse parts are parametrically identical in current rating (12 A), voltage rating (32 V AC), response time (slow-blow), package format (3AB/3AG), and physical dimensions (0.250" Dia x 1.250" L). They differ only in packaging type and product status history, not in electrical or mechanical function.

Q: What is the difference between Littelfuse and Eaton substitute parts? A: Littelfuse parts (0313012.HXP, 0313012.MXP, 0313012.VXP) are manufactured by the original equipment supplier and carry complete specification data including breaking capacity (300 A) and melting I²t (1200). Eaton parts (BK/MDL-12-R, BK/MDQ-12) are cross-manufacturer equivalents that match all critical electrical and mechanical parameters but do not provide breaking capacity or melting I²t specifications in the available data.

Q: Is the 3AB/3AG package format critical for substitution? A: Yes. The 3AB/3AG package designation specifies the holder compatibility and physical form factor (1/4" x 1-1/4"). All substitute parts maintain this package format and are mechanically compatible with existing 3AB/3AG fuse holders.

Q: Does RoHS compliance affect substitution eligibility? A: RoHS compliance is a regulatory and supply chain consideration but does not affect electrical or mechanical compatibility. The original 0313012.H is RoHS non-compliant. Littelfuse alternatives are ROHS3 compliant, while Eaton BK/MDL-12-R is ROHS3 compliant and BK/MDQ-12 is RoHS non-compliant. Selection depends on application regulatory requirements.

Q: Are there any differences in DC cold resistance between substitute parts? A: The original 0313012.H has a DC cold resistance of 0.0064 Ohms. Littelfuse active equivalents (0313012.HXP, 0313012.MXP, 0313012.VXP) have a DC cold resistance of 0.0065 Ohms, a negligible difference within normal manufacturing tolerance. Eaton parts do not provide DC cold resistance specifications.

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