{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY4123-7XX02","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY4123-7XX02","canonicalUrl":"https://aoctrl.com/siemens/5SY4123-7XX02","factsUrl":"https://aoctrl.com/api/mcp/products/5SY4123-7XX02","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON miniature circuit breaker, 5SY4123-7XX02, 1-pole, C tripping characteristic, 3.5 A rated current, 400 V AC, 10 kA (EN 60898) / 35 kA (IEC 60947-2) breaking capacity, with integrated auxiliary switch 1 NO+1 NC, 27 mm wide.","salesMarkdown":"## What this MCB covers The Siemens SENTRON 5SY4123-7XX02 is a 1-pole miniature circuit breaker rated 3.5 A at 400 V AC, with a C tripping characteristic — meaning it handles moderate inrush from motor starters and small transformers without nuisance tripping, while still protecting branch circuits against sustained overloads and short circuits. The built-in auxiliary switch (1 NO + 1 NC) saves a DIN slot versus a separate accessory, which matters when you're packing 1-pole breakers into a tight sub-panel. At 27 mm wide (1 width unit), it fits standard 18 mm pitch enclosures. The combined terminal at top and bottom accepts solid or stranded wire from 0.75 mm² up to 35 mm², with a tightening torque range of 2.5 to 3.5 N·m. Ambient temperature range -25 to +45 °C covers most indoor industrial conditions. Rated breaking capacity under UL 1077 and CSA C22.2 No. 235 is 5 kA, so it's accepted in North American supplementary protector applications. Overvoltage category III, energy limiting class 3. Sealable, with touch protection on the terminals.","metaTitle":"Siemens 5SY4123-7XX02 SENTRON MCB, 1P C 3.5A, 10kA","metaDescription":"Siemens SENTRON 5SY4123-7XX02 miniature circuit breaker, 1-pole, C-curve, 3.5 A, 10 kA per EN 60898, 35 kA per IEC 60947-2. Active production, sourced to order. 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":"27 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 ... +45 °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","Design of the product":"With auxiliary switch 1 NO+1 NC","Energy limiting class":"3","Number of width units":"1","Number of poles / Note":"1P","acc. to DIN EN 81346-2":"F","Combined Terminal Bottom":"Yes","Suitability for operation":"Mechanical engineering / industry","Current / at AC / rated value":"3.5 A","Tripping characteristic class":"C","at DC / rated value / maximum":"72 V","acc. to EN 60898 / rated value":"10 kA","Position / of power supply cord":"Any","acc. to IEC 60947-2 / rated value":"35 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 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":"440 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":"https://cdn.aoctrl.com/269e868a1e70833e360c5b3856bc5441.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=324838&mlfb=5SY4123-7XX02","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SY4123-7XX02/alternatives.json"},"ai":{"faq":[{"question":"What is the breaking capacity of 5SY4123-7XX02?","answer":"10 kA per EN 60898 and 35 kA per IEC 60947-2 at 400 V AC. Under UL 1077 and CSA C22.2 No. 235 it's rated 5 kA."},{"question":"Will 5SY4123-7XX02 drop into a panel specified around 5SY7140-8CC?","answer":"Both are 1-pole SENTRON MCBs on the same DIN-rail footprint, so mechanical fit is the same. The deciding factor is the electrical spec: the 5SY4123-7XX02 is a 3.5 A C-curve; the 5SY7140-8CC is a different rating and curve. Verify the branch circuit's required current and trip characteristic before swapping."},{"question":"Where can I buy 5SY4123-7XX02?","answer":"Sourced and quoted to order through independent distribution. Submit an RFQ for current availability and pricing."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY4123-7XX02","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/5SY4123-7XX02 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}}