15. COMPARISON OF NEMA AND IEC STANDARDS
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European IEC STANDARDS
NEMA AND IEC STANDARDS
European IEC specifcations 144 & 529 defne the degree of protection provided to electrical enclosures to
safeguard personnel against electric shock an equipment within the enclosures from environmental contami-
nation such as entry of water. This is expressed by the letters IP followed by two numbers.
In the USA, NEMA and UL have established a rating system for enclosures which provides different levels of
protection. A direct comparison between IEC and NEMA is not possible but the following table gives an ap-
proximate guide.
IP Defnition
Protection to
IEC 144/855420
Protection to NEMA
enclosure type
NEMA Defnition
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
-
-
Dusttight and protected against
water jets
IP 65
NEMA 12
induct use
dusttight &
driptight
Dusttight and protected against
heavy seas
IP 66
NEMA 35
dusttight
driptight
Dusttight and protected against
heavy seas
IP 66
NEMA 4
dusttight
watertight
-
-
NEMA 4X
dusttight
watertight
corrosion
resistant
Dusttight and protected against
water entry at one meter immersion
IP 67
-
-
Dusttight and protected against
heavy submersion
IP 68
NEMA 6
submersible
watertight
dusttight sleet
(ice) resistant
indoor & outdoor
Protection against sleet (ice) not
specifed by IEC
-
NEMA 13
oiltight & dusttight