{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SY8420-8BB08","brand":"Siemens","brandSlug":"siemens","productSlug":"5SY8420-8BB08","canonicalUrl":"https://aoctrl.com/siemens/5SY8420-8BB08","factsUrl":"https://aoctrl.com/api/mcp/products/5SY8420-8BB08","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SY8420-8BB08 miniature circuit breaker, 4-pole, 20 A rated, D tripping characteristic, 30 kA IEC 60947-2 breaking capacity, 400 V AC.","salesMarkdown":"The Siemens SENTRON 5SY8420-8BB08 is a 4-pole miniature circuit breaker rated 20 A with a D tripping characteristic and a 30 kA breaking capacity per IEC 60947-2 at 400 V AC. The magnetic-only trip design (no thermal element) suits it for applications where ambient temperature varies or where precise short-circuit protection is needed and overload protection is handled upstream or by the load itself. Under UL 1077 / CSA C22.2 No. 235 the interrupting rating drops to 5 kA, so if the installation falls under North American code, verify the available fault current at the point of use. The D curve's magnetic trip threshold is roughly 10–20× In, which means it holds through the inrush of a 15 kW motor direct-on-line but still clears a bolted fault fast. Storage range extends to -40 to +75 °C.","metaTitle":"Siemens 5SY8420-8BB08 SENTRON MCB, 4P, 20 A, D Curve, 30 kA","metaDescription":"Siemens 5SY8420-8BB08 SENTRON miniature circuit breaker, 4-pole, 20 A, D tripping characteristic, 30 kA IEC breaking capacity, 400 V AC. Current lifecycle. Quoted to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["4-Pole MCB (DIN Rail)"],"specifications":{"Depth":"76 mm","Solid":"0.75 ... 35 mm²","Width":"72 mm","title":"5SY8420-8BB08","Height":"90 mm","Sealable":"Yes","Stranded":"0.75 ... 35 mm²","Rated Value":"50/60 Hz","description":"Miniature circuit breaker 400 V 25kA, 4-pole, 20 A, D=70 mm only magnetic tripping","Halogen-Free":"Yes","Silicon-Free":"Yes","Mounting type":"Quick assembly system","During Storage":"-40 ... +75 °C","Number of poles":"4","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":"Only magnetic tripping operation","Number of width units":"4","Number of poles / Note":"4P","acc. to DIN EN 61346-2":"F","Combined Terminal Bottom":"Yes","Suitability for operation":"Mechanical engineering / industry","Current / at AC / rated value":"20 A","Tripping characteristic class":"D","at DC / rated value / maximum":"72 V","Position / of power supply cord":"Any","acc. to IEC 60947-2 / rated value":"30 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,"stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/ebabe620ae5e1d1e0a42f34f0a1f8238.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=474850&mlfb=5SY8420-8BB08"},"ai":{"faq":[{"question":"Where can I buy 5SY8420-8BB08 and get a price?","answer":"Sourced through independent distribution and quoted to order against an RFQ. Submit an RFQ for current availability and pricing."},{"question":"What is the breaking capacity of 5SY8420-8BB08?","answer":"30 kA per IEC 60947-2 at 400 V AC. Under UL 1077 / CSA C22.2 No. 235 the rating is 5 kA."},{"question":"What conductor sizes does the 5SY8420-8BB08 accept?","answer":"Solid or stranded copper from 0.75 mm² up to 35 mm². The combined terminal accepts both types without lug changes."},{"question":"What compliance documentation does Siemens provide for 5SY8420-8BB08?","answer":"The breaker carries IEC 60947-2 and UL 1077 / CSA C22.2 No. 235 ratings. The product is halogen-free and silicon-free. Standard RoHS and REACH declarations accompany the shipment."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SY8420-8BB08","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/5SY8420-8BB08 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}}