{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SM3444-8LA","brand":"Siemens","brandSlug":"siemens","productSlug":"5SM3444-8LA","canonicalUrl":"https://aoctrl.com/siemens/5SM3444-8LA","factsUrl":"https://aoctrl.com/api/mcp/products/5SM3444-8LA","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SM3 series RCCB, 4-pole, Type A, selective, In: 40 A, IΔn: 100 mA, Un AC: 400 V, with thermal overload protection.","salesMarkdown":"The Siemens SENTRON 5SM3444-8LA is a 4-pole residual current circuit breaker (RCCB) in the selective (time-delayed) design, Type A, rated 40 A at 400 V AC with a 100 mA trip threshold. The selective characteristic means it holds through short-duration earth faults and transient surges up to 5 kA surge current resistance, letting a downstream RCCB trip first — so only the faulted branch drops out, not the whole submain. That coordination matters in a distribution board feeding multiple circuits where you want the closest device to the fault to open, not the upstream main. Rated for 10 kA short-circuit current rating (SCCR) at 400 V AC, overvoltage category III, so it sits comfortably in a commercial or industrial sub-distribution board where fault levels are moderate. The 4-pole construction switches all lines including neutral, and the built-in thermal overload protection adds a second layer — it's not just a plain RCCB, it also protects against sustained overcurrent on the phase conductors. ## Ambient limits and panel fit The 45 °C ceiling is the running limit — if the panel ambient pushes above that, you need to derate or ventilate. Mounts on DIN rail (REG), any orientation, 4 width units (72 mm at 18 mm per unit), 70 mm installation depth. IP20 with connected conductors in an installed distribution board — standard for enclosed panels, not for wet locations. Finger and back-of-hand safe per the shock protection class, so live terminals are shielded when the front cover is on.","metaTitle":"Siemens SENTRON 5SM3444-8LA RCCB, 40A 100mA 4P Type A Select","metaDescription":"Siemens SENTRON 5SM3444-8LA RCCB, 4-pole, Type A, selective, 40 A, 100 mA, 400 V AC. Current production. Quoted to order against RFQ.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Residual Current Breakers (RCCB/RCBO)"],"specifications":{"Maximum":"45 °C","Minimum":"-25 °C","Rated Value":"50 Hz","Mounting type":"DIN rail (REG)","Number of poles":"4","lifecycle_stage":"current","Mounting position":"any","Installation depth":"70 mm","Product brand name":"SENTRON","Product variations":"With thermal overload protection","Maximum Permissible":"75 °C","Minimum Permissible":"-40 °C","Product designation":"RCCB","Protection class IP":"IP20, if the distribution board is installed, with connected conductors","at AC / rated value":"400 V","Overvoltage category":"III","Design of the product":"Selective","Number of width units":"4","Type of fault current":"A","circuit-breaker / Design":"5SM3","Short-circuit current rating":"10 kA","Current / at AC / rated value":"40 A","Product feature / silicon-free":"Yes","For Testing Equipment / Minimum":"100 V","Position / of power supply cord":"top or bottom","Protection against electrical shock":"Finger and back-of-hand safe","Surge current resistance / rated value":"5 kA","Switching function / short-term delayed":"No","Tripping residual current / rated value":"100 mA","Size of installation devices / acc. to DIN 43880":"1","Mechanical service life (switching cycles) / typical":"10 000"}},"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=306689&mlfb=5SM3444-8LA","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SM3444-8LA/alternatives.json"},"ai":{"faq":[{"question":"What does the selective (time-delayed) design mean on this RCCB?","answer":"Selective means the 5SM3444-8LA is intentionally delayed to allow a downstream RCCB to trip first on a fault. This prevents a nuisance trip on the upstream main when a branch circuit has a temporary earth leakage. The surge current resistance is rated at 5 kA, so it won't false-trip on lightning or switching transients."},{"question":"What is the 5SM3444-8LA's rated residual current and current rating?","answer":"Rated residual tripping current is 100 mA, rated continuous current is 40 A at 400 V AC, 50 Hz. The Type A designation means it detects AC sinusoidal fault currents plus pulsed DC fault currents up to 6 mA — covers most modern electronic loads like VFDs, switching power supplies, and LED drivers."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SM3444-8LA","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/5SM3444-8LA 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}}