{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8340-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8340-8","canonicalUrl":"https://aoctrl.com/siemens/5SY8340-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8340-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY8340-8, 3-pole miniature circuit breaker, 40 A rated current, D tripping characteristic, 25 kA breaking capacity per IEC 60947-2.","salesMarkdown":"On DC circuits the same standard gives it 15 kA. For UL 489 / CSA C22.2 No. 235 installations the interrupting rating is 5 kA — enough for most North American branch circuits but check your available fault current. Terminal design is combined top and bottom — line and load can enter from either side, which simplifies busbar routing in a crowded enclosure. ## Thermal management and environment Rated 40 A at 45 °C ambient; at 50 °C it derates to 38.76 A, and at 55 °C to 37.48 A. The surrounding temperature influence curve is published: max 95 % RH up to 55 °C, dropping to 55 % at 70 °C and 35 % at the 75 °C maximum. That matters when the breaker sits next to a contactor bank or drive that raises cabinet internal temperature. IP20 with connected conductors — standard for a DIN-rail MCB; no washdown rating, so keep it inside the enclosure. Halogen-free and silicon-free construction, sealable with a lead seal. Vibration resistance per IEC 60068-2-6: ±1 mm at 5-25 Hz, 50 m/s² at 25-150 Hz.","metaTitle":"Siemens 5SY8340-8 SENTRON MCB, 40 A, 3P, D Curve, 25 kA","metaDescription":"Siemens 5SY8340-8 SENTRON miniature circuit breaker, 40 A, 3-pole, D tripping characteristic, 25 kA breaking capacity per IEC 60947-2. Active production. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["3-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"54 mm","title":"5SY8340-8","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Miniature circuit breaker 400 V D=70 mm 25 kA according to EN 60947-2, 3P, D40","Halogen-Free":"Yes","Silicon-Free":"Yes","Design Of Pole":"3P","Number Of Poles":"3","lifecycle_stage":"current","Fastening Method":"Quick assembly system","Mounting Position":"any","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Miniature circuit breaker","acc. to IEC 81346-2":"F","at AC / rated value":"40 A","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","acc. to DIN EN 61346-2":"F","at 45 °C / rated value":"40 A","at 50 °C / rated value":"38.76 A","at 55 °C / rated value":"37.48 A","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Number Of Modular Width Units":"3","Tripping Characteristic Class":"D","Position / Of Power Supply Cord":"Any","acc. to IEC 60947-2 / rated value":"25 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","Type Of Voltage / Of The Operating Voltage":"AC","at AC / acc. to UL 1077 and CSA C22.2 No.235":"5 kA","vibration resistance / acc. to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","Product Component / Neutral Conductor Switching":"No","with multi-phase operation / at AC / rated value":"440 V","operating voltage / at DC / rated value / maximum":"72 V","with single-phase operation / at AC / rated value":"440 V","Mechanical Service Life (Switching Cycles) / Typical":"10 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/59990e84886a202f0e75c73586c4ea6a.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=502757&mlfb=5SY8340-8"},"ai":{"faq":[{"question":"What are the key ratings for the 5SY8340-8?","answer":"40 A rated current, D tripping characteristic, 3-pole. Breaking capacity: 25 kA at 440 V AC per IEC 60947-2, 15 kA DC per IEC 60947-2, and 5 kA per UL 1077 / CSA C22.2 No. 235."},{"question":"Where can I buy the 5SY8340-8?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."},{"question":"What compliance documentation does Siemens provide for the 5SY8340-8?","answer":"The breaker carries IEC 60947-2 and UL 1077 / CSA C22.2 No. 235 certifications. RoHS and REACH declarations are standard from Siemens for this SENTRON series."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8340-8","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/5SY8340-8 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}}