{"product_id":"square-d-mja36400-400a-600v-3-pole-plug-in-circuit-breaker","title":"Square D MJA36400 - 400 A, 600 V, 3-Pole Plug-In Circuit Breaker | AmpState","description":"\u003cdiv\u003e\n\u003cp\u003eThe Square D MJA36400 is a rugged, plug-in molded case circuit breaker designed to deliver fast, reliable overcurrent protection for three-phase systems. With a 400 A rating and 600 V maximum, this 3-pole device is a robust choice for panelboards and load centers that demand dependable branch circuit protection in residential, commercial, and light industrial settings.\u003c\/p\u003e \u003cul\u003e \u003cli\u003e\n\u003cstrong\u003eFast plug-in connection\u003c\/strong\u003e enables quick installation and stress-free replacement, minimizing downtime during maintenance or panel upgrades.\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eThermal-magnetic trip unit\u003c\/strong\u003e provides stable, repeatable protection against overcurrent and short circuits across varying temperatures, helping prevent nuisance trips and equipment damage.\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eOEM-compatible design\u003c\/strong\u003e is engineered to fit matching Square D panelboards and load centers, ensuring a clean, reliable integration without compatibility concerns.\u003c\/li\u003e \u003cli\u003e\n\u003cstrong\u003eVersatile 3-pole configuration\u003c\/strong\u003e supports three-phase distribution, ideal for larger branch circuits and feeders in commercial and light industrial environments.\u003c\/li\u003e\n\u003c\/ul\u003e \u003ch3\u003eTechnical specifications\u003c\/h3\u003e\n\u003cul\u003e \u003cli\u003eManufacturer: Square D\u003c\/li\u003e \u003cli\u003ePart number: MJA36400\u003c\/li\u003e \u003cli\u003eType: Thermal-magnetic molded case circuit breaker (MCCB)\u003c\/li\u003e \u003cli\u003eAmperage rating: 400 A\u003c\/li\u003e \u003cli\u003eVoltage rating: 600 V\u003c\/li\u003e \u003cli\u003eNumber of poles: 3\u003c\/li\u003e \u003cli\u003eMounting style: Plug-in\u003c\/li\u003e \u003cli\u003eApplication: Branch circuit overcurrent and short-circuit protection\u003c\/li\u003e\n\u003c\/ul\u003e \u003cp\u003e\u003cstrong\u003eWhy this model stands out\u003c\/strong\u003e: designed for straightforward upgrades and reliable protection, the MJA36400 slots directly into compatible Square D panels, delivering quick installation without compromising safety or performance. The thermal-magnetic trip mechanism ensures predictable responses to overloads and faults, so downstream equipment such as motors, lighting, and feeders stay protected under normal operation and fault conditions alike. This is a practical choice for electricians and facility managers who value uptime, panel compatibility, and consistent protection in demanding environments.\u003c\/p\u003e \u003ch3\u003eUse cases and installation considerations\u003c\/h3\u003e\n\u003cul\u003e \u003cli\u003eIdeal for replacing worn or failing breakers in existing Square D panelboards and load centers, where a direct plug-in fit saves time and reduces labor costs.\u003c\/li\u003e \u003cli\u003eSuitable for three-phase commercial applications and light industrial installations requiring 400 A feeder or branch-circuit protection at up to 600 V.\u003c\/li\u003e \u003cli\u003eExcellent for panel modernization projects where OEM compatibility and reliable trip performance are priorities.\u003c\/li\u003e\n\u003c\/ul\u003e \u003cp\u003eStocked by AmpState, the Square D MJA36400 delivers high-capacity protection with straightforward plug-in installation, helping you keep critical electrical infrastructure safe, compliant, and up to code.\u003c\/p\u003e\n\u003c\/div\u003e","brand":"Amp State","offers":[{"title":"Default Title","offer_id":46355348324514,"sku":null,"price":710.0,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0666\/8094\/6850\/files\/schnieder_and_square_d_breaker_and_panel_6fa132c0-2c0a-4de0-a496-eef96c44f2f6.png?v=1764691458","url":"https:\/\/www.ampstate.com\/products\/square-d-mja36400-400a-600v-3-pole-plug-in-circuit-breaker","provider":"Ampstate Electric Corporation","version":"1.0","type":"link"}