{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8404-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8404-8","canonicalUrl":"https://aoctrl.com/siemens/5SY8404-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8404-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON miniature circuit breaker, 5SY8404-8, D characteristic, 4-pole, 4 A (45 °C), 400 V AC, 50 kA IEC 60947-2, 4 MW wide, quick-assembly system.","salesMarkdown":"The Siemens SENTRON 5SY8404-8 is a 4-pole miniature circuit breaker with a D tripping characteristic, rated 4 A at 45 °C ambient on a 400 V AC system. On DC circuits it's rated 15 kA per IEC 60947-2, and under UL 1077 / CSA C22.2 No. 235 it carries 5 kA at AC — relevant if the panel ships to North America under those standards. The 4-pole version (4P) switches all three phases plus the neutral — common in three-phase distribution where the neutral needs overcurrent protection or is switched for isolation. Mounting position is any; the quick-assembly system clips onto the standard DIN rail, occupying 4 modular width units (about 72 mm). ## Temperature derating and environmental limits The 5SY8404-8 is rated 4 A at 45 °C, but the current must be derated as ambient rises: 3.9 A at 50 °C, 3.8 A at 55 °C. Above that, the surrounding temperature influence curve caps at 95% relative humidity up to 55 °C, then 55% RH up to 70 °C, and 35% RH up to 75 °C maximum. The minimum storage/operating temperature is -40 °C, covering cold-start conditions in outdoor or unheated installations. ## Mechanical and vibration withstand Tested to IEC 60068-2-6 for vibration resistance: ±1 mm displacement at 5 to 25 Hz, and 50 m/s² acceleration at 25 to 150 Hz. That covers most industrial panel vibration environments — motor starters, conveyor lines, compressor skids — without the breaker nuisance-tripping or loosening on the DIN rail. Overvoltage category III and degree of pollution 3 confirm it's rated for fixed installations inside the distribution board, not for the final outlet.","metaTitle":"Siemens SENTRON 5SY8404-8 MCB, D Curve, 4 A, 4-Pole, 50 kA","metaDescription":"Siemens SENTRON 5SY8404-8 miniature circuit breaker, D tripping characteristic, 4 A rated at 45 °C, 4-pole, 50 kA breaking capacity per IEC 60947-2. Current production. Sourced to","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["4-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"72 mm","title":"5SY8404-8","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, 4P, D4","Halogen-Free":"Yes","Silicon-Free":"Yes","Number Of Poles":"4","Type Of Voltage":"AC","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":"400 V","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","Combined Terminal Top":"Yes","Number Of Poles / Note":"4P","acc. to DIN EN 61346-2":"F","at 45 °C / rated value":"4 A","at 50 °C / rated value":"3.9 A","at 55 °C / rated value":"3.8 A","Combined Terminal Bottom":"Yes","Suitability For Operation":"Mechanical engineering / industry","Number Of Modular Width Units":"4","Tripping Characteristic Class":"D","Position / Of Power Supply Cord":"Any","acc. to IEC 60947-2 / rated value":"50 kA","Product Feature / Touch Protection":"Yes","Supply Voltage Frequency / Rated Value":"50/60 Hz","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","vibration resistance / acc. to IEC 60068-2-6":"±1mm at 5 to 25Hz; 50m/s² at 25 to 150Hz","Product Function / 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 (Operating Cycles) / Typical":"10 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/df1b39814d335756685905a2b0d0de05.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=255018&mlfb=5SY8404-8"},"ai":{"faq":[{"question":"What is the breaking capacity of the 5SY8404-8?","answer":"50 kA per IEC 60947-2 at 400 V AC, 15 kA per IEC 60947-2 at DC, and 5 kA per UL 1077 / CSA C22.2 No. 235 at AC. The 50 kA figure tells you it can handle high fault currents typical of strong utility supplies without needing an upstream current-limiting device."},{"question":"What does the D tripping characteristic mean for this breaker?","answer":"The D curve (10–20× In) is designed for loads with high inrush currents — motor starters, transformers, welding equipment — where a B or C curve would trip on startup. At 4 A rated, the magnetic trip picks up between 40 A and 80 A."},{"question":"Will the 5SY8404-8 fit in a panel designed for a 4-pole MCB from the same SENTRON family?","answer":"Yes. The 5SY8404-8 uses the standard SENTRON quick-assembly system, mounts on DIN rail in any position, and occupies 4 modular width units (72 mm wide, 70 mm installation depth). It fits the same panel cutouts and busbar systems as other SENTRON 4-pole MCBs."},{"question":"What compliance documentation is available for the 5SY8404-8?","answer":"The breaker carries IEC 60947-2 and UL 1077 / CSA C22.2 No. 235 ratings, and is designated per IEC 81346-2 and DIN EN 61346-2. It is halogen-free and silicon-free, supporting RoHS and REACH compliance requirements. Specific declarations are available through the manufacturer's documentation portal."},{"question":"Where can I buy the 5SY8404-8 and how is it quoted?","answer":"The 5SY8404-8 is sourced through independent industrial-automation distribution. Pricing and availability are confirmed at quote time against an RFQ — no online stock or price is published. Submit an RFQ for current lead time and volume pricing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8404-8","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/5SY8404-8 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}}