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Electrical Enclosure Ratings Explanation

There are three fundamental enemies of enclosed electrical equipment: water, dust, and

explosion. In the United States, Canada and many other North and South American markets,there is a body of standards for describing the resistance of an electrical enclosure to theseenemies; it is the set of standards published by the National Electrical Manufacturers Association.In Europe and many other countries, similar standards are published by the IEC.

Below is an overview of the various electrical enclosure ratings available for EASIs EasiLiner,PowerLiner, CompuLiner and Euro Series lighting products. It is the dealers responsibilityto interview client personnel or make first-hand observations of conditions and then specify whichof these ratings need met on each product ordered from EASI.

Ratings of the National Electrical Manufacturers Association

CLASS 1 GENERAL PURPOSE

For indoor use only; primarily utilized as protection against contact with the enclosed circuits.Normal rating used for general electrical equipment in both commercial and industrial applications.

CLASS 3R WEATHER RESISTANT

(also known as "Weatherproof", "Splashproof", "Sleetproof", Raintight) For outdoor use;protects enclosed components from wind-blown dust, rain, sleet and external icing. The mainintended purpose of a 3R rated enclosure is to protect the actual electrical components inside theenclosure from direct contact with water; this is often accomplished by allowing water to enter thetop and drain out of the bottom of the enclosure. Such drain-through function is permitted so longas the enclosed components do not come into direct contact with water.

CLASS 4 WATERTIGHT (also known as "Hoseproof")Similar to "3" above; but also passes the "Hose Test", which is described as: a 1 inch nozzle,delivering 65 gpm of water, from a distance of 10 feet, from all directions, for a 5 minute timeperiod, no water leak to the interior is allowed. This enclosure is used in settings where a hose isused to wash down equipment. This not a corrosion resistant rating, where rusting of theenclosure is a concern.

CLASS 4X WATERTIGHT

Same as "4" above; also constructed of corrosion resistant materials suitable for the corrosiveconditions of the installed location. The generally preferred materials are polyester/glass, stainless

steel, and epoxy coatings. This enclosure is the "standard" in food processing or corrosivechemical environments. Underwriters Laboratories recognizes #304 stainless steel as anacceptable NEMA 4X material, in fact requiring no specific corrosion resistance testing ofenclosures made of this material.

CLASS 7 EXPLOSION PROOF (Class 1: Gases)

CLASS I is a location with an atmospheric mixture of flammable gases. The enclosure isintended to contain an explosion internally while the surrounding ambient gas-air mixture isnot ignited. These enclosures should also be rated NEMA 4 so as to be suitable forinstrument service.

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DIVISION I is a location in which hazardous mixtures are expected during normaloperations.

DIVISION II is a location in which the flammables are contained and escape only during asystem rupture.

GROUP A: acetylene

GROUP B: hydrogen, manufactured gas or equivalent

GROUP C: ethyl ether, ethylene, cyclopropane, or equivalent

GROUP D: gasoline, hexane, naphtha, butane, alcohol, acetone, lacquer solvents, naturalgas, and equivalents. Commonly used by oil refineries, petrochemical plants and sewagetreatment plants.

CLASS 9 EXPLOSION PROOF (Class II: Dusts)

CLASS II is a location hazardous because of combustible dusts. The enclosure excludes

the dust from the internal power sources and ignition is thereby prevented. It also must notoverheat when covered by a layer of the dust.

DIVISION I locations are where suspended combustible dusts are expected duringnormal operations.

DIVISION II locations are where normal operations cannot put the dust into atmosphericsuspension.

GROUP E: Metal dusts, electrically conductive, such as those of aluminum, magnesium,and their alloys.

GROUP F: Other dusts, electrically conductive, such as those of carbon black, coal, and

coke.

GROUP G: Dusts such as those of grain, flour, and starch.

CLASS 12 INDUSTRIAL USE

Intended for indoor use; provides protection against dust and dripping liquids; used in machineshops, fabrication facilities, and environments with heavy concentrations of airborne dust. Manyindustrial facilities require NEMA 12 rated electrical enclosures for all plant mounted equipment,but often permit NEMA 1 rated enclosures inside equipment rooms and MCC housings.

NOTE: The above information is intended only to generally describe the enclosures commonlyused in our industry. Detailed rules and application information can be found in the current National

Electrical Code and in other governing authority publications; these must be followed for specificinstallations.

EASI U-Box enclosures are available from stock as NEMA 1, 3R, 4, 4X, or 12 ratings. Aproduct order must specify which rating is required for each product placement. Orders receivedby EASI without specifying the NEMA enclosure rating for each product will be routinely built andshipped as standard NEMA 1 ratings.

Many EASI products are available in a NEMA explosion proof rating of Class 1 Division 1.Please inquire about your specific needs prior to ordering.

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IEC-IP Ratings and Definitions

IP Ratings or International Protection Code is a standard rating system that indicates the type ofenvironments a particular instrument is capable of operating (according to rules IEC529). The IPrating takes the form of IP-**. Where each * is replaced by a number corresponding to aparticular rating; the first number indicates the Solids rating, and the second number indicates theLiquids rating. The following list explains each of the numbers. IP-**

Protection Index - Solids

First Character:

0 = No special protection

1 = Protected against solid objects 50> mm in diameter (ie: hand contact)

2 = Protected against solid objects 12> mm in diameter (ie: fingers)

3 = Protected against solid objects 2.5> mm in diameter (ie: tools, wires)

4 = Protected against solid objects 1 mm in diameter (ie: small tools, small wires)

5 = Dust Protected (no harmful deposits)

6 = Dust Tight (no deposits)

Protection Index - Liquids

Second Character:

0 = No special protection

1 = Protected against vertical dripping water (condensation)

2 = Protected against dripping water when tilted 15 degrees on either side

3 = Protected against rain up to 60 degrees vertical

4 = Protected against any water jet, any direction

5 = Protected against water jet with nozzle

6 = Protected against incoming water similar to sea waves

7 = Protected against the effects of immersion

8 = Protected against submersion

The IEN-IP Standards do not specify ratings specifically for explosion proof requirements. Inthese locations, the international standard is the NEMA based Class X and Division X ratingmethod, as in Class I, Division II. Please see the above NEMA standard ratings for explosionproof applications for these ratings.