What the digits mean
IP ratings (IEC 60529) use two digits after the letters IP. The first, 0 to 6, rates solids and dust protection. The second, 0 to 9 (or 9K for washdown), rates liquid protection. Read left to right: solids first, then liquids.
What shows up on nameplates
● IP54: dust protected, splash protected from any direction — baseline TEFC
● IP55/56: dust protected, protected against low or powerful water jets
● IP65/66: fully dust-tight, jet or powerful-jet protected — washdown territory
Why the mismatch costs money
An IP54 motor hosed down daily is a slow-motion failure. Moisture works past the seal and drain plugs, insulation resistance drifts down, bearings pick up rust, all well before the motor's expected life is up. It rarely looks dramatic. It looks like a motor failing insulation tests two or three years early. The fix is the right rating for the actual duty, not a better brand.
It's not just the motor frame
The IP rating on a nameplate describes the enclosure as built, but conduit entries, cable glands, and junction box gaskets all have to hold up their end too. A properly rated IP66 motor with a loose conduit fitting or a degraded gasket performs like whatever its weakest sealed point allows, which is worth checking during routine inspections, not just at commissioning.
BOTTOM LINE Not sure what rating belongs on a replacement? The nameplate on the motor coming out has the answer.
