The Omron D4A0900N is a metallic limit switch box in the EN50041 body style — the global standard footprint for heavy-duty limit switches used in machine guarding, conveyor transfer stations, and process valve position feedback. The stainless steel body and IP67 rating mean it withstands washdown and corrosive atmospheres: food-and-beverage lines, chemical processing, or outdoor conveyor systems where NEMA 4X or 6P enclosures are specified. The 2NO/2NC contact form gives you one normally-open and one normally-closed pair per pole, which suits dual-channel safety circuits or switching two independent loads from a single actuator.
The AC contact rating is 5 A at 600 V. That is the maximum continuous current the contacts can make and break under AC resistive or inductive loads — sized for pilot relays, contactor coils, or small motor starters. The DC contact rating is listed as Not Rated, which means the manufacturer does not certify it for DC switching; if your circuit is DC, you need to verify the DC voltage and current against the contact material and arc-suppression method separately — do not assume it will interrupt a DC inductive load reliably. Operating temperature spans -40 to 212 °F, covering freezer applications and hot washdown zones. The NEMA enclosure ratings (3, 4, 4X, 6P, 12, 13) confirm suitability for rain, hose-down, submersion, and oil/coolant exposure — a single box that covers indoor machine-tool and outdoor weatherproof locations.
The body is a plug-in design — the switch head and receptacle are separate, so you can wire the base and then plug in the switch body without re-terminating. Two mounting holes at 76 mm vertical and 30 mm horizontal center-to-center spacing with a 0.4 in diameter match the standard EN50041 hole pattern. The box is compatible with the D4A-N series limit switch heads — you can swap actuator styles (roller lever, plunger, rod) without changing the base.