Panel-mounted controllers are offered with various front panel enclosure ratings, with costs increasing along with the degree of protection. The proper Ingress Protection (IP) rating and the National Electrical Manufacturers Association (NEMA) rating should be selected depending on the particular application.
IP ratings are usually IP65 or higher for most industrial applications. This means the controller is completely protected from dust, oil, and other non-corrosive material. The IP65 rating also ensures complete protection from contact with enclosed equipment, and from water projection by a nozzle from any direction.
Roughly corresponding to an IP65 rating would be a NEMA 4 or 4X rating. The ‘X' in a NEMA 4X rating means that the controller’s front panel will not corrode during normal operating conditions.
See related article, "Understanding Temperature Controller Technology."