Littelfuse 0251012.NRT2 Equivalent & Substitute Parts

Part Overview

The Littelfuse 0251012.NRT2 is a 12 A, 32 V AC/DC board mount axial fuse from the PICO® II 251 series, designed for through-hole applications. This part is classified as obsolete, making equivalent and substitute parts necessary for ongoing production and maintenance requirements. The fuse provides fast-blow response with a breaking capacity of 50 A AC and 300 A DC, suitable for circuit protection in low-voltage applications requiring CSA and cURus approval.

Key Parameters

Parameter	Value
Current Rating	12 A
Voltage Rating (AC)	32 V
Voltage Rating (DC)	32 V
Response Time	Fast Blow
Mounting Type	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)
Package / Case	Axial
Breaking Capacity @ Rated Voltage	50 A AC, 300 A DC
Melting I²t	45.2
Operating Temperature Range	-55°C ~ 125°C
Size / Dimension	0.110" Dia x 0.280" L (2.80mm x 7.11mm)
DC Cold Resistance	0.0059 Ohms
Approval Agency	CSA, cURus

Substitute Part Grouping Explanation

Substitution for the obsolete 0251012.NRT2 is determined by strict equivalence across the following critical parameters: current rating (12 A), AC voltage rating (32 V), DC voltage rating (32 V), response time (fast blow), mounting type (through hole), fuse type (board mount, cartridge style excluded), package type (axial), breaking capacity, melting I²t, operating temperature range, physical dimensions, and approval certifications (CSA, cURus).

Littelfuse parts 0251012.MXL, 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, and 0251012.NAT1L maintain full parametric equivalence with the original part across all electrical and mechanical specifications. These parts differ only in packaging format (bulk or cut tape) and product status (active vs. obsolete), with enhanced RoHS3 compliance.

The SCHURTER 7010.7160.13 provides direct functional equivalence with minor variations: operating temperature range (-55°C ~ 85°C vs. -55°C ~ 125°C), melting I²t (57 vs. 45.2), physical dimensions (0.093" Dia x 0.315" L vs. 0.110" Dia x 0.280" L), and package classification (cartridge, non-standard axial vs. axial). Breaking capacity is 300 A (DC only, vs. 50 A AC and 300 A DC for Littelfuse parts).

Parameter Comparison

Parameter	0251012.NRT2 (Main)	0251012.MXL	0251012.HAT1L	0251012.MRT1L	0251012.NRT1L	0251012.NAT1L	7010.7160.13
Manufacturer	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	Littelfuse Inc.	SCHURTER Inc.
Current Rating (Amps)	12 A	12 A	12 A	12 A	12 A	12 A	12 A
Voltage Rating - AC	32 V	32 V	32 V	32 V	32 V	32 V	32 V
Voltage Rating - DC	32 V	32 V	32 V	32 V	32 V	32 V	32 V
Response Time	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow	Fast Blow
Mounting Type	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole	Through Hole
Fuse Type	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)	Board Mount (Cartridge Style Excluded)
Package / Case	Axial	Axial	Axial	Axial	Axial	Axial	Cartridge, Non-Standard (Axial)
Breaking Capacity @ Rated Voltage	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	50 A AC, 300 A DC	300 A
Melting I²t	45.2	45.2	45.2	45.2	45.2	45.2	57
Operating Temperature Range	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 125°C	-55°C ~ 85°C
Size / Dimension	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.110" Dia x 0.280" L (2.80mm x 7.11mm)	0.093" Dia x 0.315" L (2.36mm x 8.00mm)
DC Cold Resistance	0.0059 Ohms	0.0059 Ohms	0.0059 Ohms	0.0059 Ohms	0.0059 Ohms	0.0059 Ohms	Not specified
Approval Agency	CSA, cURus	CSA, cURus	CSA, cURus	CSA, cURus	CSA, cURus	CSA, cURus	CSA, UR
Product Status	Obsolete	Active	Active	Active	Active	Active	Active
RoHS Status	RoHS non-compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant	ROHS3 Compliant

Engineering Selection Recommendations

For direct replacement of the obsolete 0251012.NRT2, the Littelfuse 0251012.MXL, 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, and 0251012.NAT1L are fully equivalent substitutes. All five parts maintain identical electrical and mechanical specifications while offering active product status and ROHS3 compliance. Selection among these five parts depends on packaging requirements: 0251012.MXL is supplied in bulk packaging, while 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, and 0251012.NAT1L are supplied in cut tape format.

The SCHURTER 7010.7160.13 functions as a direct alternative with documented parameter variations. This part maintains the same current rating, voltage ratings, response time, and mounting type. However, the reduced operating temperature upper limit (-55°C ~ 85°C), increased melting I²t (57 vs. 45.2), different physical dimensions, and modified breaking capacity specification require evaluation against specific application thermal and performance requirements. The SCHURTER part carries CSA and UR approvals, differing from the CSA and cURus certifications of Littelfuse parts.

Frequently Asked Questions (FAQ)

Q: Can 0251012.MXL, 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, and 0251012.NAT1L be used interchangeably with 0251012.NRT2?

A: Yes. These five Littelfuse parts are parametrically equivalent to 0251012.NRT2 across all critical electrical and mechanical parameters: 12 A current rating, 32 V AC/DC voltage ratings, fast-blow response, through-hole mounting, axial package, identical breaking capacity, melting I²t, operating temperature range, physical dimensions, and approval certifications. Differences exist only in packaging format (bulk vs. cut tape) and product status (active vs. obsolete).

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

A: The five Littelfuse substitutes differ only in packaging: 0251012.MXL is supplied in bulk packaging, while 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, and 0251012.NAT1L are supplied in cut tape format. All other specifications are identical.

Q: Can the SCHURTER 7010.7160.13 replace the 0251012.NRT2?

A: The SCHURTER 7010.7160.13 provides functional equivalence for the same current rating, voltage ratings, response time, and mounting type. However, three parameter differences exist: operating temperature range is reduced to -55°C ~ 85°C (vs. -55°C ~ 125°C), melting I²t is 57 (vs. 45.2), and physical dimensions differ (0.093" Dia x 0.315" L vs. 0.110" Dia x 0.280" L). Application requirements must be evaluated against these variations.

Q: Are all substitute parts RoHS compliant?

A: All active substitute parts (0251012.MXL, 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, 0251012.NAT1L, and 7010.7160.13) are ROHS3 compliant. The original 0251012.NRT2 is RoHS non-compliant.

Q: What approval certifications do these parts carry?

A: Littelfuse parts (0251012.MXL, 0251012.HAT1L, 0251012.MRT1L, 0251012.NRT1L, 0251012.NAT1L) carry CSA and cURus approvals. The SCHURTER 7010.7160.13 carries CSA and UR approvals.

Q: Do physical dimensions affect board layout compatibility?

A: The Littelfuse substitutes maintain identical dimensions (0.110" Dia x 0.280" L). The SCHURTER 7010.7160.13 has different dimensions (0.093" Dia x 0.315" L), which may affect board layout and mounting hole spacing. Physical compatibility must be confirmed for the SCHURTER part.

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