Understanding IP & NEMA Ratings

IP ratings have sprung onto the outdoor lighting scene because they are a more accurate means of classifying a fixtures ability to stop the ingress of dirt and/or water.  As we all know, the better the seal the cleaner the fixture interior, and the better the fixture performs over the long run.  "Wet Location" and NEMA ratings have always been vague and subject to interpretation.  With the IP rating system, the degrees of protection are most commonly expressed as "IP" (Ingress protection) followed by two numbers where the numbers define the degree of protection. The first digit (Foreign Bodies Protection i.e. "dirt") shows the extent to which the equipment is protected against particles (i.e. "crud").  The second digit (Water Protection) indicates the extent of protection against water entering the fixture.  There is also a third number that can be used to define impact protection but no fixture manufacturers that we are aware of have picked up on that rating so it isn't included here.  Kudos to the lighting fixture manufacturers that rate their fixtures using IP ratings.

Where : "IP" + "s" + "l" = the proper fixture for the application!

s = solids ("dirt or crud"), l = liquids (water)

First Index - Solids Protection

Index Protection against solid objects (foreign bodies)
0 No special protection
1 Large foreign bodies, diam. >50mm
2 Medium-sized foreign bodies, diam. >12mm
3 Small foreign bodies, diam. >2.5mm
4 Granular foreign bodies, diam. >1mm
5 Dust protected; dust deposits are permitted, but their volume must not affect the function of the unit.
6 Dust-proof

 

Second Index - Water Protection

Index Protection against water Protection from condition
0 No special protection
1 Water dripping/falling vertically Condensation/Light rain
2 Water sprayed at an angle (up to 15 degrees from the vertical) Light rain with wind
3 Spray water (any direction up to 60 degrees from the vertical) Heavy rainstorm
4 Spray water from all directions, (limited ingress permitted) Splashing
5 Low pressure water jets from all directions, (limited ingress permitted) Hose down, residential
6 High pressure jets from all directions, (limited ingress permitted) Hose down, commercial.
eg. Ship decks
7 Temporary immersion, 15 cm to 1m Immersion in tank
8 Permanent Immersion, under pressure For use on Titanic recovery vehicle

   

NEMA Ratings

There are many NEMA ratings available for enclosures.  Following, is a brief explanation of NEMA ratings most typically seen in lighting and power applications:

NEMA 1 General Purpose - Indoors
Type 1 enclosures are intended for general purpose indoor use primarily to provide a degree of protection against contact with the enclosed equipment or locations where unusual service conditions do not exist.

NEMA 2 Drip Proof - Indoors
Type 2 enclosures are intended for general purpose indoor use primarily to provide a degree of protection against limited amounts of falling water and dirt.

NEMA 3 Dust Tight, Rain Tight, & Ice/Sleet resistant - Indoors/Outdoors
Type 3 enclosures are intended for general purpose outdoor use primarily to provide a degree of protection against windblown dust, rain, and sleet; and to be undamaged by the formation of ice on the enclosure.

NEMA 3R Rain Proof & Ice/Sleet Proof - Indoors/Outdoors
Type 3R enclosures are intended for general purpose outdoor use primarily to provide a degree of protection against falling rain; and to be undamaged by the formation of ice on the enclosure.

NEMA 3S Dust Tight, Rain Tight, & Ice/Sleet Proof - Outdoors
Type 3S enclosures are intended for general purpose outdoor use primarily to provide a degree of protection against sleet; and to be undamaged by the formation of ice on the enclosure.

NEMA 4 Water Tight & Dust Tight - Indoors/Outdoors
Type 4 enclosures are intended for general purpose indoor or outdoor use primarily to provide a degree of protection against windblown dust and rain, splashing water, and hose directed water; and to be undamaged by the formation of ice on the enclosure.

NEMA 4x Water Tight, Dust Tight, & Corrosion Resistant - Indoors/Outdoors
Type 4X enclosures are intended for general purpose indoor and outdoor use primarily to provide a degree of protection against corrosion, windblown dust and rain, splashing water, and hose-directed water; and to be undamaged by the formation of ice on the enclosure.

NEMA 6 Submersible, Water Tight, Dust Tight, & Ice/Sleet Resistant - Indoors/Outdoors
Type 6 enclosures are intended for general purpose indoor or outdoor use primarily to provide a degree of protection against the entry of water during temporary submersion at a limited depth; and to be undamaged by the formation of ice on the enclosure.

NEMA 12 Industrial Use - Dust Tight & Drip Tight - Indoors
Type 12 enclosures are intended for industrial indoor use primarily to provide a degree of protection against dust, falling dirt, and dripping noncorrosive liquids.

 

Comparing NEMA and IP enclosure ratings. 
C
omparing NEMA & IP ratings is like comparing apples and oranges so user beware!
 

Enclosure type

 IP23 

 IP30 

 IP32 

 IP55 

 IP64 

 IP65 

 IP66 

 IP67 

1

             
2  

           
3 & 3R        

     
4            

 
4X            

 
6              

12