{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"0451.500NR","brand":"Littelfuse Inc.","brandSlug":"littelfuse-inc","productSlug":"0451.500NR","canonicalUrl":"https://icboms.com/littelfuse-inc/0451.500NR","factsUrl":"https://icboms.com/api/mcp/products/0451.500NR","rawCanonicalId":null},"summary":{"shortDescription":"Littelfuse Inc. NANO²® 451 series, Surface Mount Fuse, Fast Blow, 500 mA, 125 V AC/DC, 50 A Breaking Capacity, 2-SMD Square End Block Package, Tape & Reel.","salesMarkdown":"The 0451.500NR: No official successor order code is recorded from Littelfuse for this specific line. A board-spin or a parametric substitute evaluation is the practical next step for new builds. ## What the ratings mean for fit Rated 500 mA at 125 V AC or DC — this fuse clears a sustained overcurrent above the 500 mA threshold in a fast-blow response, meaning it opens quickly on a fault but may nuisance-blow on a brief inrush that exceeds the melting I²t of 0.0795. Breaking capacity is 50 A at the rated voltage — the fuse can safely interrupt a fault current up to 50 A without rupturing the case. That ceiling is low compared to modern SMD fuses; verify the prospective short-circuit current at the fuse position stays under 50 A. 2-SMD square end block package measuring 6.10 mm x 2.69 mm x 2.69 mm — the footprint is the same as the standard NANO² 451 series. ## Approvals and compliance CSA and UL approved — the fuse carries acceptance for North American and Canadian regulatory jurisdictions.","metaTitle":"Littelfuse 0451.500NR NANO² 451 SMD Fuse, 500 mA, 125 V","metaDescription":"Obsolete Littelfuse 0451.500NR NANO² 451 surface-mount fast-blow fuse, 500 mA at 125 V AC/DC, 50 A breaking capacity.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Obsolete","categoryPath":["Circuit Protection"],"specifications":{"Mfr":"Littelfuse Inc.","Color":"-","Series":"NANO²® 451","Package":"Tape & Reel (TR)","Fuse Type":"Board Mount (Cartridge Style Excluded)","Melting I²t":"0.0795","Mounting Type":"Surface Mount","Response Time":"Fast Blow","Package / Case":"2-SMD, Square End Block","Product Status":"Obsolete","Approval Agency":"CSA, UL","lifecycle_stage":"unknown","Size / Dimension":"0.240\\\" L x 0.106\\\" W x 0.106\\\" H (6.10mm x 2.69mm x 2.69mm)","DC Cold Resistance":"0.42 Ohms","Voltage Rating - AC":"125 V","Voltage Rating - DC":"125 V","Current Rating (Amps)":"500 mA","Operating Temperature":"-55°C ~ 125°C","Breaking Capacity @ Rated Voltage":"50A"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$1.5300","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.icboms.com/2e33e7b2503f3f5110226be89402b64a.pdf","sourceUrl":null},"ai":{"faq":[{"question":"What is the breaking capacity of the 0451.500NR?","answer":"50 A at the rated 125 V AC or DC. This is the maximum fault current the fuse can safely interrupt."},{"question":"What package does the 0451.500NR use?","answer":"2-SMD square end block, the standard NANO² 451 footprint, supplied on Tape & Reel."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://icboms.com/littelfuse-inc/0451.500NR","citationPolicyUrl":"https://icboms.com/llms.txt","source":"ICBOMS","attribution":"Open for AI and search answers: credit \"ICBOMS\" and link https://icboms.com/littelfuse-inc/0451.500NR when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-07-20T14:34:45.345Z","lastPublished":"2026-07-20T14:34:45.345Z","indexable":true}}