{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SL1240-7MB","brand":"Siemens","brandSlug":"siemens","productSlug":"5SL1240-7MB","canonicalUrl":"https://aoctrl.com/siemens/5SL1240-7MB","factsUrl":"https://aoctrl.com/api/mcp/products/5SL1240-7MB","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SL1240-7MB miniature circuit breaker, 2-pole, C tripping characteristic, 40 A rated current, 230/400 V AC, 3 kA breaking capacity per IEC 60947-2.","salesMarkdown":"## What this 40 A C-curve MCB is and where it fits The Siemens 5SL1240-7MB is a 2-pole miniature circuit breaker from the SENTRON family, rated 40 A with a C tripping characteristic. It protects branch circuits in residential and infrastructure panels against overload and short-circuit faults up to 3 kA per IEC 60947-2 at 230/400 V AC. The C-curve means the magnetic trip operates at 5 to 10 times rated current — suited for moderate inrush loads like small motors, transformers, and lighting banks where a B-curve would nuisance-trip but a D-curve is unnecessary. ## Panel fit and mounting constraints Occupies 2 modular width units (36 mm) on a DIN rail, with a depth of 76 mm and an installation depth of 70 mm behind the panel surface. Mounting position is unrestricted, and the IP20 rating with connected conductors is standard for enclosed distribution boards. Sealable design allows the installer to lock the toggle position — useful for compliance with local isolation rules or to prevent unauthorized reset on a critical circuit. ## Environmental and compliance profile Halogen-free and silicon-free construction, rated for ambient temperatures from -40 °C to 75 °C. Overvoltage category III and pollution degree 2 suit fixed-installation mains circuits.","metaTitle":"Siemens 5SL1240-7MB SENTRON MCB, 2-Pole C-Curve 40A","metaDescription":"Siemens 5SL1240-7MB SENTRON miniature circuit breaker, 2-pole, C-curve, 40A rated at 230/400V AC, 3kA breaking capacity per IEC 60947-2. Current production. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["2-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Width":"36 mm","title":"5SL1240-7MB","Height":"90 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Circuit breaker 230/400V 3kA, 2pole, C, 40A","Halogen-Free":"Yes","Silicon-Free":"Yes","Design Of Pole":"2P","Number Of Poles":"2","lifecycle_stage":"current","Mounting Position":"any","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"2","Product Designation":"Miniature circuit breaker","at AC / rated value":"40 A","protection class IP":"IP20, with connected conductors","Overvoltage Category":"III","at 30 °C / rated value":"40 A","Suitability For Operation":"Residential buildings/infrastructure","Number Of Modular Width Units":"2","Tripping Characteristic Class":"C","at DC / rated value / maximum":"72 V","supply voltage / at AC / rated value":"230 V","according to IEC 60947-2 / rated value":"3 kA","Type Of Voltage / Of The Operating Voltage":"AC","with multi-phase operation / at AC / maximum":"440 V","Value Range / Of The Supply Voltage Frequency":"50/60 Hz","with multi-phase operation / at AC / rated value":"440 V","with single-phase operation / at AC / rated value":"253 V","Mechanical Service Life (Switching Cycles) / Typical":"4 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":null,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/a3c8967e55c90b9510221ee51cba6a57.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=1046734&mlfb=5SL1240-7MB"},"ai":{"faq":[{"question":"What is the breaking capacity of 5SL1240-7MB?","answer":"Rated 3 kA according to IEC 60947-2 at 230/400 V AC. This is the short-circuit withstand rating for the 2-pole configuration."},{"question":"Where can I buy 5SL1240-7MB and how is it quoted?","answer":"Sourced and quoted to order through independent distribution. Submit an RFQ for current availability and pricing — no stock figures are published on this listing."},{"question":"Will 5SL1240-7MB drop into a panel designed for 5SL4106-7CC?","answer":"Not without rewiring. The 5SL1240-7MB is a 2-pole, 40 A unit occupying 36 mm (2 MW), whereas the 5SL4106-7CC is a 1-pole, 6 A unit at 18 mm (1 MW). The footprint, pole count, and current rating differ completely."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SL1240-7MB","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/5SL1240-7MB 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}}