Omron J7MN-3P-4 MCCB, 4A, 3-Pole, Active Production

In a motor branch circuit, that typically protects a fractional-horsepower motor or a control transformer secondary—oversize it and you lose the protection; undersize and nuisance tripping on inrush. The three-pole configuration handles three-phase loads, so it fits standard 3-wire plus ground motor circuits.