The Square D MJA36400 is a 400-amp, 3-pole, 600V PowerPact M-Frame molded case circuit breaker with an ET 1.0 solid-state electronic trip unit. Designed for heavy-duty feeder and main circuit protection in commercial and industrial applications, it features I-Line plug-in mounting on the line side and mechanical lug terminals on the load side. The electronic trip provides LI (Long-Time, Instantaneous) protection with an 80% continuous current rating. With an interrupting rating of 100kA at 240V and 65kA at 480V, it handles demanding power distribution environments. UL Listed, CSA Approved, CE marked, and NOM certified. Replaces legacy M-Frame breakers in Square D I-Line switchboards and panelboards.
| Specification | Value |
|---|---|
| Amperage | 400A |
| Poles | 3 |
| Voltage | 240/480/600VAC |
| Interrupt Rating | 100kA @ 240V · 65kA @ 480V · 25kA @ 600V |
| Frame Size | M-Frame (800A Frame) |
| Mounting Type | I-Line Plug-In (line) / Mechanical Lugs (load) |
| Trip Type | Electronic — ET 1.0 Solid State |
| Trip Function | LI — Long-Time, Instantaneous |
| Wire Size | 3/0 AWG–350 kcmil (Al/Cu) |
| Phase | 3-Phase |
| Standards | UL 489, CSA C22.2 No.5, IEC 60947-2, NOM, CE |
| Temperature Rating | 40°C |
Replaces: MA36400, MC36400, MH36400, NJA36400
Square D PowerPact M-Frame 400A 3-pole circuit breaker. In stock at AllBreakerSales.com. Call (877) 611-0034 for same-day pricing. Genuine OEM parts, ships from US warehouse.
Brand: Square D | Series: PowerPact M-Frame | Catalog Number: MJA36400
MJA36250 - Square D PowerPact M-Frame | MJA36300 - Square D PowerPact M-Frame | MJA36350 - Square D PowerPact M-Frame | MJA36500 - Square D PowerPact M-Frame | MJA36600 - Square D PowerPact M-Frame