What is NEMA?

National Electrical Manufacturers Association (NEMA) is the association of U.S. manufacturers of electrical equipment that defines the main set of construction standard for the United States and Canada.
Adherence to these standards is guaranteed by the UL certification.
NEMA coding (Type 12, 3R/4, 4/4X) can be compared with the IP coding (IP 54, 56, 56) but compared to the latter is more comprehensive and includes other factors such as protection against corrosion.

Pfannenberg cooling units from NEMA series are UL listed.

NEMA vs IP rating

NEMA rating can be compared with IP rating - although there is no direct correspondence - but the first one is more complete and also includes other factors such as the protection from corrosion.

NEMA PROTECTION 12 3R/4 4/4X
access to hazardous parts x x x
ingress of solid foreign objects (falling dirt) x x x
ingress of water (dripping and light splashing) x x x
ingress of water (rain, snow, and sleet)   x x
ingress of solid foreign objects (dust,lint, fibers, and flyings) x x x
oil and coolant seepage x    
ingress of water (Hosedown and splashing water)   x x
corrosive agents     x
IP EQUIVALENT IP 54 IP 56 IP 56