{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SM3742-0","brand":"Siemens","brandSlug":"siemens","productSlug":"5SM3742-0","canonicalUrl":"https://aoctrl.com/siemens/5SM3742-0","factsUrl":"https://aoctrl.com/api/mcp/products/5SM3742-0","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SM3 series RCCB, 4-pole, 25 A rated, 500 mA AC fault current, 400 V, DIN rail mount, instantaneous type.","salesMarkdown":"The Siemens SENTRON 5SM3742-0 is a 4-pole residual current circuit breaker (RCCB) rated for 25 A at 400 V AC, with a 500 mA trip threshold for AC fault currents. It's an instantaneous type — no intentional delay — so it trips as soon as the residual current exceeds that threshold, which matters for shock protection in circuits where you need fast disconnection. That 10 kA SCCR is typical for a distribution board downstream of a larger upstream breaker. ## Temperature derating and conductor sizing The 25 A rating holds at 40 °C and 45 °C, then derates linearly: 24 A at 50 °C, 23 A at 55 °C, down to 20 A at 70 °C. If the panel runs hot, factor that in — at 60 °C you lose 3 A off the headline number. Terminal capacity accepts 1.5 mm² minimum up to 25 mm² — solid or stranded. That covers most distribution wiring up to 6 AWG. Silicon-free construction, so it's safe for use in environments sensitive to silicone outgassing.","metaTitle":"Siemens SENTRON 5SM3742-0 RCCB, 25 A, 500 mA, 4-pole","metaDescription":"Siemens SENTRON 5SM3742-0 RCCB, 25 A rated, 500 mA trip, 400 V AC, 4-pole, DIN rail mount, IP20. Current lifecycle, available to order. Quoted on request.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":null,"categoryPath":["Residual Current Breakers (RCCB/RCBO)"],"specifications":{"Depth":"77 mm","Width":"72 mm","Height":"90 mm","Maximum":"25 mm²","Minimum":"1.5 mm²","at 40 Cel":"25 A","at 45 Cel":"25 A","at 50 Cel":"24 A","at 55 Cel":"23 A","at 60 Cel":"22 A","at 65 Cel":"21 A","at 70 Cel":"20 A","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","Operating frequency":"50Hz","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":"Instantaneous","Number of width units":"4","Type of fault current":"AC","acc. to DIN EN 61346-2":"F","acc. to DIN EN 81346-2":"F","I2t-value / permissible":"70 000 A²·s","circuit-breaker / Design":"5SM3","Short-circuit current rating":"10 kA","Current / at AC / rated value":"25 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","Switching function / short-term delayed":"No","Tripping residual current / rated value":"500 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=529214&mlfb=5SM3742-0","alternativesUrl":"https://aoctrl.com/api/mcp/products/5SM3742-0/alternatives.json"},"ai":{"faq":[{"question":"What is the 5SM3742-0 used for?","answer":"It's a 4-pole RCCB for AC residual current protection in distribution boards, rated 25 A, 500 mA trip, 400 V AC, on DIN rail."},{"question":"Where can I buy the 5SM3742-0?","answer":"Sourced and quoted to order against an RFQ through independent distribution; availability and pricing confirmed at quote time."},{"question":"What are the key ratings of the 5SM3742-0?","answer":"25 A rated current, 500 mA residual trip, 400 V AC, 10 kA SCCR, 4-pole, instantaneous AC type."},{"question":"What compliance documentation does Siemens provide for the 5SM3742-0?","answer":"The part carries the SENTRON brand and is designed to DIN EN 61346-2 and DIN EN 81346-2 standards; specific RoHS/REACH/UL/IEC documentation is available from the manufacturer on request."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SM3742-0","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/5SM3742-0 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}}