{"schemaVersion":"matrix-product-facts/v1","identity":{"mpn":"5SJ4108-8HG42","brand":"Siemens","brandSlug":"siemens","productSlug":"5SJ4108-8HG42","canonicalUrl":"https://aoctrl.com/siemens/5SJ4108-8HG42","factsUrl":"https://aoctrl.com/api/mcp/products/5SJ4108-8HG42","rawCanonicalId":null},"summary":{"shortDescription":"Siemens SENTRON 5SJ4 miniature circuit breaker, 1-pole, 8 A rated AC, D tripping characteristic, 18 mm width, 70 mm depth.","salesMarkdown":"The Siemens SENTRON 5SJ4108-8HG42 is a 1-pole miniature circuit breaker rated 8 A at AC with a D tripping characteristic. It occupies one modular width unit (18 mm) and mounts on a standard DIN rail in any position. The D curve means it tolerates high inrush currents — typical for motor or transformer branch circuits where the magnetic trip is set to 10–20× rated current, so nuisance tripping on start-up is less likely than with a B or C curve. ## Thermal derating and ambient limits Rated 8 A at 30 °C and 40 °C without derating. At 45 °C the continuous current drops to 7.8 A, at 50 °C to 7.6 A, at 55 °C to 7.4 A, and at 60 °C to 7.2 A. The operating range spans -40 °C to 75 °C. Pollution degree 3 and overvoltage category 3 suit this breaker for industrial control panels where conductive dust and transient surges are expected. Sealable terminals help lock settings for compliance-sensitive installations.","metaTitle":"Siemens SENTRON 5SJ4108-8HG42 Miniature Circuit Breaker, 1-P","metaDescription":"Siemens SENTRON 5SJ4108-8HG42 miniature circuit breaker, 1-pole, 8 A rated AC, D tripping curve. 18 mm wide, 70 mm deep. IP20/IP40. Active production. Sourced to order.","metaKeywords":null},"attributes":{"series":null,"packageCase":null,"mountingType":null,"rohsStatus":null,"productStatus":"Active","categoryPath":["1-Pole MCB (DIN Rail)"],"specifications":{"Depth":"70 mm","Width":"18 mm","title":"5SJ4108-8HG42","Height":"121 mm","Maximum":"75 °C","Minimum":"-40 °C","Sealable":"Yes","description":"Circuit breaker 10kA, 1-pole, D, 8A according to UL 489-277V","Halogen-Free":"Yes","Silicon-Free":"Yes","Number Of Poles":"1","lifecycle_stage":"current","Fastening Method":"on standard mounting rail","Mounting Position":"any","Installation Depth":"70 mm","Product Brand Name":"SENTRON","Degree Of Pollution":"3","Product Designation":"Miniature circuit breakers","at AC / rated value":"8 A","protection class IP":"IP20, with connected conductors, IP 40 in the handle range","Overvoltage Category":"3","Tunnel Terminals Top":"No","Vibration Resistance":"50 m/s² at 25 to 150Hz and 60m/s² at 35Hz (4sec)","Combined Terminal Top":"Yes","Design Of The Product":"Miniature circuit-breaker 5SJ4","Product Function / Note":"Terminal tightening torque for Cu, 60/75°C; 3.5Nm/31lb.in","Tunnel Terminals Bottom":"No","according to EN 61346-2":"F","at 30 °C / rated value":"8 A","at 40 °C / rated value":"8 A","at 45 °C / rated value":"7.8 A","at 50 °C / rated value":"7.6 A","at 55 °C / rated value":"7.4 A","at 60 °C / rated value":"7.2 A","Combined Terminal Bottom":"Yes","according to IEC 81346-2":"F","Suitability For Operation":"Mechanical engineering / industry","Number Of Modular Width Units":"1","Tripping Characteristic Class":"D","at DC / rated value / maximum":"60 V","Position / Of Power Supply Cord":"Any","Product Feature / Touch Protection":"Yes","according to EN 60898 / rated value":"10 kA","supply voltage / at AC / rated value":"400 V","Supply Voltage Frequency / Rated Value":"50 Hz","according to IEC 60947-2 / rated value":"15 kA","installation environment regarding EMC":"Suitable for environment B (immunity to interference not applicable)","Type Of Voltage / Of The Operating Voltage":"AC/DC","insulation voltage (Ui) / at AC / rated value":"440 V","Product Component / Neutral Conductor Switching":"No","Mechanical Service Life (Switching Cycles) / Typical":"10 000"}},"commercial":{"minOrderQty":null,"leadTime":null,"referencePrice":"$38.10 – $99.49","stockQuantity":0,"priceTiers":null},"links":{"datasheetUrl":"https://cdn.aoctrl.com/0936210f59346ca04545b85de740e979.pdf","sourceUrl":"https://support.industry.siemens.com/webbackend/api/ProductSupport/TechnicalData?language=en&region=cn&productId=157649&mlfb=5SJ4108-8HG42"},"ai":{"faq":[{"question":"What are the key dimensions for panel layout?","answer":"Width 18 mm (one modular unit), height 121 mm, depth 70 mm. Mounts on standard DIN rail in any position."}],"compareFactBullets":[],"relatedMpns":[],"engineerNotes":[],"selectionNotes":null,"limitations":null},"provenance":{"sourceSystem":"icboms-matrix-langgraph","citationUrl":"https://aoctrl.com/siemens/5SJ4108-8HG42","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/5SJ4108-8HG42 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}}