{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8408-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8408-8","canonicalUrl":"https://aoctrl.com/siemens/5SY8408-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8408-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY8 series, miniature circuit breaker, 4-pole, D characteristic, 8 A rated current, 400 V AC, 40 kA IEC 60947-2, 72 mm wide, 76 mm deep.","salesMarkdown":"The Siemens 5SY8408-8 is a SENTRON 5SY8 miniature circuit breaker, 4-pole with D tripping characteristic, rated 8 A at 400 V AC. This is the current-production variant — lifecycle status is active, so it's the part you spec into a new BOM or order as a direct replacement for an existing 5SY8 install. At 8 A rated current, it's a common feeder for a small motor group or a control transformer. If you're specifying for a UL 508A panel, the UL 1077/CSA C22.2 No. 235 rating is 5 kA — a different standard, so verify the SCCR requirement against your assembly rating. Overvoltage category III means it's rated for fixed-installation distribution boards, not just downstream equipment. The 72 mm width (4 width units at 18 mm each) is the standard DIN-rail footprint for a 4-pole MCB — it occupies four adjacent positions on the rail. Any mounting position is acceptable. Humidity derating applies: max 95% RH at 55 °C, 55% at 70 °C, 35% at 75 °C. The terminals accept solid or stranded copper from 0.75 mm² up to 35 mm², with a tightening torque of 2.5 to 3.5 N·m. Sealable (padlockable) per the spec, which matters for lockout/tagout compliance. Rated per IEC 60947-2 (40 kA at 400 V AC, 15 kA at 72 V DC) and UL 1077 / CSA C22.2 No. 235 (5 kA). Halogen-free and silicon-free construction. The product designation per DIN EN 61346-2 and DIN EN 81346-2 is function code F (protective device). Touch protection is provided on the terminals.","metaTitle":"Siemens 5SY8408-8 SENTRON MCB, 4P, D-curve, 8 A, 40 kA","metaDescription":"Siemens 5SY8408-8 SENTRON miniature circuit breaker, 4-pole, D tripping characteristic, 8 A rated, 40 kA IEC 60947-2, 400 V AC. Current production. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["4-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Solid":"0.75 ... 35 mm²","Width":"72 mm","title":"5SY8408-8","Height":"90 mm","Sealable":"Yes","Stranded":"0.75 ... 35 mm²","Rated Value":"50/60 Hz","description":"Miniature circuit breaker 400 V D=70 mm 25 kA according to EN 60947-2, 4P, D8","Halogen-Free":"Yes","Silicon-Free":"Yes","Wertebereich":"-25 ... +55 °C","Mounting type":"Quick assembly system","Number of poles":"4","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Ambient temperature":"-40 ... +75 °C","Product designation":"Miniature circuit breaker","Protection class IP":"IP20, with connected conductors","at AC / rated value":"400 V","Overvoltage category":"III","Combined Terminal Top":"Yes","Number of width units":"4","Number of poles / Note":"4P","acc. to DIN EN 61346-2":"F","acc. to DIN EN 81346-2":"F","Combined Terminal Bottom":"Yes","circuit-breaker / Design":"5SY8","Suitability for operation":"Mechanical engineering / industry","Current / at AC / rated value":"8 A","Tripping characteristic class":"D","at DC / rated value / maximum":"72 V","Position / of power supply cord":"Any","acc. to IEC 60947-2 / rated value":"40 kA","Product feature / Touch protection":"Yes","Influence of the surrounding temperature":"max. 95% to 55°C, max. 55% to 70°C, max. 35% to 75°C","at DC / acc. to IEC 60947-2 / rated value":"15 kA","at AC / acc. to UL 1077 and CSA C22.2 No.235":"5 kA","Tightening torque / with screw-type terminals":"2.5 ... 3.5 N·m","Product function / neutral conductor switching":"No","with multi-phase operation / at AC / rated value":"440 V","with single-phase operation / at AC / rated value":"440 V","Mechanical service life (switching cycles) / typical":"10 000","Tightening torque [lbf·in] / with screw-type terminals":"22 ... 31 lbf·in","AWG number / as coded connectable conductor cross section":"18 ... 4"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/337eedab2db0dbf35c073814e8ce4969.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=89854&mlfb=5SY8408-8"},"ai":{"faq":[{"question":"Who supplies 5SY8408-8 and how is it quoted for volume purchases?","answer":"Sourced and quoted to order against an RFQ through independent industrial-automation distribution. Availability and current pricing are confirmed at quote time — no stock or price figures are published here."},{"question":"What compliance documentation does Siemens provide for 5SY8408-8?","answer":"The part carries IEC 60947-2 and UL 1077/CSA C22.2 No. 235 ratings. It is halogen-free and silicon-free. Standard Siemens documentation includes a CE declaration of conformity and the datasheet; RoHS and REACH compliance statements are available from the manufacturer on request."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8408-8","citationPolicyUrl":"https://aoctrl.com/llms.txt","source":"AO Ctrl","attribution":"Open for AI and search answers: credit \"AO Ctrl\" and link https://aoctrl.com/siemens/5SY8408-8 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-08-11T15:51:03.652Z","lastPublished":"2026-08-11T15:51:03.652Z","indexable":true}}