{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY3125-6","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY3125-6","canonicalUrl":"https://aoctrl.com/siemens/5SY3125-6","factsUrl":"https://aoctrl.com/api/mcp/products/5SY3125-6","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY3 series, miniature circuit breaker (MCB), 1-pole, 25 A rated current, B tripping characteristic, 4.5 kA breaking capacity per EN 60898, 6 kA per IEC 60947-2, 400 V AC, 72 V DC, IP20.","salesMarkdown":"## What this MCB does on the line The Siemens 5SY3125-6 is a 1-pole SENTRON miniature circuit breaker rated 25 A with a B tripping characteristic, meaning it trips at 3–5× rated current — the standard choice for residential and light commercial lighting and socket-outlet circuits where inrush is low. It breaks 4.5 kA per EN 60898 and 6 kA per IEC 60947-2, so it handles typical domestic and industrial fault levels up to that point without cascading upstream. The 400 V AC rating covers single-phase line-to-neutral or line-to-line applications; the 72 V DC maximum extends it to control circuits and DC auxiliary supplies. IP20 with connected conductors; install in a cabinet that keeps the front accessible for the sealable toggle. ## Breaking capacity across standards This MCB carries three breaking-capacity ratings because it is certified to multiple standards. Per EN 60898 (the household standard) it is 4.5 kA at 400 V AC. For DC circuits per IEC 60947-2 it is 15 kA at 72 V. Under UL 1077 and CSA C22.2 No. 235 it is 5 kA at 400 V AC. The energy limiting class is 3, so it limits let-through energy well enough to protect downstream components in a selective coordination scheme. Humidity tolerance: 95 % at 55 °C, derating to 35 % at 75 °C.","metaTitle":"Siemens 5SY3125-6 SENTRON MCB, 1P, 25 A, B Curve, 4.5 kA","metaDescription":"Siemens 5SY3125-6 SENTRON miniature circuit breaker, 1-pole, 25 A, B characteristic, 4.5 kA per EN 60898, 6 kA per IEC 60947-2. Active production. Quoted on request.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["1-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Solid":"0.75 ... 35 mm²","Width":"18 mm","Height":"90 mm","Sealable":"Yes","Stranded":"0.75 ... 35 mm²","Rated Value":"50/60 Hz","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","During Storage":"-40 ... +75 °C","Number of poles":"1","Type of voltage":"AC","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Ambient temperature":"-25 ... +55 °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","Energy limiting class":"3","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":"5SY3","Current / at AC / rated value":"25 A","Tripping characteristic class":"B","at DC / rated value / maximum":"72 V","acc. to EN 60898 / rated value":"4.5 kA","Position / of power supply cord":"Any","acc. to IEC 60947-2 / rated value":"6 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":"250 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,"priceTiers":null},"links":{"datasheetUrl":null,"sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=472031&mlfb=5SY3125-6","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SY3125-6/alternatives.json"},"ai":{"faq":[{"question":"How do I get current pricing and availability for 5SY3125-6?","answer":"Submit an RFQ through the storefront. Pricing and stock levels are confirmed at quote time; the part is sourced to order through independent distribution channels."},{"question":"Will 5SY3125-6 drop into a panel specified around 5SY3132-6 without rewiring?","answer":"Both are 1-pole SENTRON 5SY3 MCBs with the same 18 mm width, 90 mm height, and 76 mm depth, so the mechanical fit is identical. The difference is the current rating: 5SY3125-6 is 25 A, while 5SY3132-6 is 32 A. If the panel was wired for 32 A (larger conductor or higher load), dropping in a 25 A breaker may nuisance-trip under the original load. Check the branch-circuit load before swapping."},{"question":"What is 5SY3125-6's listed depth?","answer":"76 mm total depth, with a 70 mm installation depth behind the panel door."},{"question":"What conductor sizes does 5SY3125-6 accept?","answer":"Solid or stranded copper from 0.75 mm² up to 35 mm²."},{"question":"What compliance documentation does Siemens provide for 5SY3125-6?","answer":"The MCB carries ratings per EN 60898, IEC 60947-2, UL 1077, and CSA C22.2 No. 235. It is halogen-free and silicon-free. Standard RoHS and REACH declarations are available from Siemens documentation."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY3125-6","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/5SY3125-6 when reusing this data. Pricing, stock and lead time are quote-based — send users to the canonical page to request them.","lastUpdated":"2026-09-02T08:15:54.622Z","lastPublished":"2026-09-02T08:15:54.622Z","indexable":true}}