{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8125-8","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8125-8","canonicalUrl":"https://aoctrl.com/siemens/5SY8125-8","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8125-8","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY8 series, miniature circuit breaker, 1-pole, D-curve, 25 A, 30 kA at 400 VAC, 1 width unit.","salesMarkdown":"The D-curve (10–20× In) means it tolerates the inrush of motor starters, transformers, or discharge lamps without nuisance tripping, so it belongs in a machine control panel or a distribution board feeding inductive loads, not a general-purpose lighting final circuit. In a panel with a transformer upstream that can deliver 25 kA of fault current, this holds; if your service entrance can push 50 kA, you step up to a higher-rated frame. The 15 kA DC rating at 72 V DC covers battery-backed control circuits or DC bus distribution — useful in UPS-fed panels. D-curve (10–20× In) means magnetic trip happens between 250 A and 500 A for this 25 A unit. That's wide enough to pass the starting surge of a 7.5 kW DOL motor without blinking, but still clears a bolted fault fast. At one width unit (18 mm), it occupies a single module slot.","metaTitle":"Siemens 5SY8125-8 SENTRON MCB, 1P D 25 A, 30 kA","metaDescription":"Siemens SENTRON 5SY8125-8 miniature circuit breaker, 1-pole, D-curve, 25 A, 30 kA breaking capacity at 400 VAC. Active production, available to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["1-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"18 mm","title":"5SY8125-8","Height":"90 mm","Maximum":"31 lbf·in","Minimum":"22 lbf·in","Sealable":"Yes","Rated Value":"50/60 Hz","description":"Circuit breaker 230/400 V D=70 mm 25 kA according to EN 60947-2, 1P, D25","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","Number of poles":"1","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","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":"1","Number of poles / Note":"1P","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":"25 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":"30 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","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"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/a5c059f274d9eda2bd36069c4de7e47f.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=152450&mlfb=5SY8125-8"},"ai":{"faq":[{"question":"Where can I buy the 5SY8125-8?","answer":"Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time."},{"question":"What is the breaking capacity of the 5SY8125-8?","answer":"30 kA at 400 V AC per IEC 60947-2, and 15 kA at 72 V DC per the same standard. Under UL 1077 it's rated 5 kA."},{"question":"Will the 5SY8125-8 drop into a panel built for the 5SY4140-7?","answer":"Both are 1-pole SENTRON MCBs on an 18 mm footprint with the same quick-assembly DIN-rail mount. The difference is the curve and rating: the 5SY8125-8 is D-curve at 25 A with 30 kA breaking capacity, while the 5SY4140-7 is a different variant. Panel cutouts and busbar connections are identical."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8125-8","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/5SY8125-8 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}}