{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4408-8CV","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4408-8CV","canonicalUrl":"https://aoctrl.com/siemens/5SY4408-8CV","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4408-8CV","rawCanonicalId":null},"summary":{"shortDescription":"Siemens 5SY4408-8CV, MCB Icu=15kA 400V 4P D8.","salesMarkdown":"## What the ratings mean for fit The Siemens 5SY4408-8CV is a 4-pole miniature circuit breaker (MCB) with a D8 tripping characteristic and a rated ultimate short-circuit breaking capacity (Icu) of 15 kA at 400 V AC. The D-curve (8× to 14× In) is sized for loads with high inrush current — motor starters, transformers, or capacitive banks — where a B or C curve would nuisance-trip on startup. The 15 kA Icu at 400 V means this breaker can safely interrupt a fault current up to that level without welding its contacts or cascading failure upstream; that figure governs the SCCR (short-circuit current rating) of the downstream panel section. ## Deployment context This MCB snaps onto a standard 35 mm DIN rail inside a panel enclosure. The 4-pole format (3 poles + switched neutral) is typical for three-phase four-wire systems (TN-S or TN-C-S) where the neutral requires overcurrent protection. The D8 curve and 15 kA Icu suit it for motor control centers or distribution sub-panels feeding industrial loads with high inrush.","metaTitle":"Siemens 5SY4408-8CV MCB, 15kA Icu 400V 4P D8","metaDescription":"Siemens 5SY4408-8CV MCB, 15kA Icu at 400V, 4-pole D8 curve. Current lifecycle stage. Sourced to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Miniature Circuit Breakers (MCB)"],"specifications":{"title":"5SY4408-8CV","description":"MCB Icu=15KA 400V 4P D8","lifecycle_stage":"current"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/5d469399643d047660e80ece076b0f40.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1531619&mlfb=5SY4408-8CV"},"ai":{"faq":[{"question":"What is the Icu rating of the 5SY4408-8CV?","answer":"The rated ultimate short-circuit breaking capacity (Icu) is 15 kA at 400 V AC. This is the maximum fault current the breaker can safely interrupt."},{"question":"What does the D8 curve mean on this MCB?","answer":"The D8 tripping characteristic (8× to 14× In) is designed for loads with high inrush current such as motors, transformers, or welding equipment. The '8' indicates the rated current of 8 A per pole."},{"question":"Where can I buy the 5SY4408-8CV?","answer":"This part is sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4408-8CV","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/5SY4408-8CV 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}}