The first digit of the IP code describes protection against solid objects and dust, the second against water. In IP55, the first 5 means dust is not completely excluded but cannot get in far enough to disturb operation; the second 5 means a low-pressure water jet aimed at the housing from any direction causes no harm. On HEM Motor three-phase series, IP55 is standard for both the frame and the terminal box.

IP55 does not cover running under water or cleaning with pressurised water. The catalogue also lists an IP56 option; for wash-down areas, heavy dust or coastal sites, describe the environment and state the requirement when ordering. Explosive atmospheres are not addressed by the IP rating but by separate certification; a standard motor is not designed for that purpose.

To keep the protection effective on site, the cable gland must match the cable diameter, unused entries must be closed with blanking plugs, and the terminal box cover must be tightened with its gasket in place. For coastal and salty air, see the article on motor protection in salty environments.