Littelfuse 0255.500NRT1 Equivalent & Substitute Parts

Part Overview

The Littelfuse 0255.500NRT1 is a 500 mA, 125 V AC/DC board mount axial fuse from the PICO® 255 series. This component is classified as obsolete, making identification of suitable substitute parts essential for ongoing design support and procurement continuity. The PICO® 255 series has been superseded by newer product lines that maintain electrical and mechanical compatibility while offering improved availability and compliance status.

Substiute Parts

0255.500NRT1

Littelfuse Inc.In Stock: 10500255.500NRT1 Datasheet

Current PartRFQ

0251.500NRT1L

LittelfuseIn Stock: 446070251.500NRT1L Datasheet

MFR RecommendedRFQ

Key Parameters

Substitute Part Grouping Explanation

Substitution of the 0255.500NRT1 is based on strict equivalence of the following electrical and mechanical parameters:

• Current Rating: 500 mA (exact match required)
• Voltage Rating: 125 V AC and 125 V DC (exact match required)
• Response Time: Fast Blow (exact match required)
• Breaking Capacity: 50A AC, 300A DC (exact match required)
• Mounting Type: Through Hole axial configuration (exact match required)
• Fuse Type: Board Mount, Cartridge Style Excluded (exact match required)

The substitute part 0251.500NRT1L from the PICO® II 251 series meets all these criteria. While dimensional tolerances differ slightly (0.110" Dia vs. 0.095" Dia), the axial through-hole mounting configuration remains compatible with standard PCB footprints designed for this fuse category.

Parameter Comparison

Engineering Selection Recommendations

The 0251.500NRT1L is the direct substitute for the obsolete 0255.500NRT1. Selection of this substitute part is justified on the following grounds:

• Electrical equivalence: All critical electrical parameters (current rating, voltage ratings, response time, breaking capacity) are identical.
• Mechanical compatibility: Both parts are through-hole axial fuses with matching length (0.280" L). Diameter tolerance variation (0.095" to 0.110") is within acceptable PCB hole sizing standards for this component category.
• Product status: The substitute part is active and in production, ensuring long-term availability and supply chain continuity.
• Compliance improvement: The substitute part achieves ROHS3 compliance and carries expanded regulatory approvals (CCC, CSA, cURus, TUV) compared to the original part (CSA, UL).
• Inventory availability: The substitute part maintains substantial stock levels (44,501 pcs), supporting immediate procurement needs.

Frequently Asked Questions (FAQ)

Q: Can the 0251.500NRT1L be used as a direct replacement for the 0255.500NRT1 in existing designs?

A: Yes. Both parts are electrically and mechanically equivalent for the specified application. The dimensional difference (0.110" Dia vs. 0.095" Dia) does not affect compatibility with standard through-hole PCB footprints for this fuse category.

Q: What is the difference between the PICO® 255 and PICO® II 251 series?

A: The PICO® II 251 is the successor product line to the PICO® 255. Both series maintain identical electrical specifications for equivalent current and voltage ratings. The PICO® II 251 offers improved regulatory compliance (ROHS3) and expanded certification coverage.

Q: Are there any performance differences between these two parts?

A: No. Both parts share identical current rating (500 mA), voltage ratings (125 V AC/DC), response time (Fast Blow), and breaking capacity (50A AC, 300A DC). The DC cold resistance specification (0.302 Ohms) is provided for the substitute part and represents normal operating characteristics for this fuse type.

Q: What packaging options are available for the substitute part?

A: The 0251.500NRT1L is supplied in Cut Tape (CT) packaging. The main part (0255.500NRT1) does not specify packaging format in the provided data.

Q: Does the substitute part meet current regulatory requirements?

A: Yes. The 0251.500NRT1L is ROHS3 compliant and REACH unaffected. It carries certifications from CCC, CSA, cURus, and TUV, providing broader regulatory coverage than the obsolete original part.