Enclosure types

Europe IEC specifications 144 & 529 define the degree of protection provided electrical enclosures to safeguard personnel against electric shock and equipment within the enclosure from environmental contamination such as entry of water. This is expressed by the letters IP followed by two numerals.

In the USA, NEMA and UL have established a rating system for enclosures which provides for different levels of protection. A direct comparison between IEC and NEMA is not possible but the following table gives an approximate guide.

Definition	Protection to IEC 144/855420	Protection to NEMA enclosure type	NEMA Definition
Protection against solid objects greater than 12 mm	IP 20	NEMA 1 (ventilated)	general purpose
Protection against solid objects greater than 2.5 mm	IP 30	NEMA 1	general purpose
Protection against solid objects greater than 12 mm and dripping water	IP 21	NEMA 2 (ventilated)	drip proof
Protection against solid objects greater than 2.5 mm and dripping water	IP 31	NEMA 2	drip proof
Protection against solid objects greater than 12 mm and dripping water	IP 24	NEMA 3R (ventilated)	rain proof, sleet (ice) resistant outdoor use
Protection against solid objects greater than 2.5 mm and dripping water	IP 34	NEMA 3R	rain proof, sleet (ice) resistant outdoor use
Protection against dust and splashing liquids	IP 54	-	-
Dustight and protected against water jets	IP 65	NEMA 12	industrial use dustight & driptight
Dustight and protected against heavy seas	IP 66	NEMA 35	dustight, driptight
Dustight and protected against heavy seas	IP 66	NEMA 4	dustight, watertight
		NEMA 4X	dustight, watertight corrosion resistant
Dustight and protected against water entry at one meter immersion	IP 67
Dustight and protected against heavy submersion	IP 68	NEMA 6	submersible watertight, dustight sleet (ice) resistant indoor & outdoor
Protection against sleet (ice) not specified by IEC		NEMA 13	oiltight & dustight