For instrumentation we usually reference NEMA pertaining to what the IEC calls ingress protection. NEMA ICS 6 and NEMA 250 are examples. Generally, NEMA TYPE 4 is suitable for outdoor installations. Stainless steel or plastic enclosures that provide sufficient corrosion protection to pass a 100-hour salt spray test are NEMA type 4X. Indoor ventilated enclosures are NEMA type 1. That suggests that it should keep someone from being hurt as entries are small enough that you cannot poke your finger into the box.
The enclosure types are defined in NEMA 250. Many NEMA standards were formerly ANSI standards for colors, symbols, signs, etc. Others define rigid steel and EMT conduit requirements, Watthour meters, smoke detectors, adjustable speed drives, UPS transfer switches, fire pump controllers, MCC schematic symbols, etc.
