40 A, 4-pole, C-curve — what it means on the panel
The EZ9F34440 is a 40 A, 4-pole miniature circuit breaker from Schneider Electric's Easy9 range, built to IEC 60898-1. The C-curve (magnetic trip 5–10 × In) means it handles moderate inrush — typical for lighting banks, small motor circuits, and general distribution loads where the start-up surge is higher than a resistive heater but not as high as a transformer bank. The 4.5 kA breaking capacity at 400 V AC is the Icn rating; the Ics (service breaking capacity) is the same 4.5 kA at 100 % Icn, so the breaker can reclose after clearing a fault at its full rating without derating — useful for a distribution board where you want to restore power without swapping the device.
Clip-on mounting to standard DIN rail (35 mm per EN 60715). The 72 mm width (8 × 9 mm pitches) and 81 mm height fit a standard distribution board cutout; depth of 66.5 mm leaves clearance for a 60 mm deep enclosure with the door closed. Tightening torque of 3.5 N.m on both line and load terminals; use a torque screwdriver to avoid terminal heating at full load.