This standard covers enclosures for electrical equipment rated not more than 1000 V and intended to be
installed and used as follows:
a. enclosures for indoor locations, Types 1, 2, 5, 12, 12K, and 13;
b. enclosures for indoor or outdoor locations, Types 3, 3X, 3R, 3RX, 3S, 3SX, 4, 4X, 6,
and 6P; and
c. enclosures for hazardous (classified) locations, Types 7 and 9
This standard covers the requirements to provide protection to the enclosed equipment against specific
environmental conditions. The requirements of this standard mandate that enclosures and equipment
shall be installed and used in accordance with the manufacturer’s instructions and 110.3(B) of
ANSI/NFPA 70, National Electrical Code® (NEC®).
This standard covers the requirements for enclosures that are installed and ready for use in
nonhazardous (unclassified) locations.
This standard also covers the requirements for dust-tight enclosures that are installed and ready for use
where permitted by NEC® in Class II, Division 2; Class III, Division 1; Class III, Division 2; and Zone 22
hazardous (classified) locations as defined by the NEC®, or by ANSI/UL 121201, Nonincendive Electrical
Equipment for Use in Class I and II, Division 2, and Class III, Divisions 1 and 2 Hazardous (Classified)
Locations (UL 121201). Where dust-tight enclosures are integral to or incorporate separable electrical
connections (e.g., plug and receptacle, plug and connector body, inlet and connector body) for use in
Class II, Division 2; Class III, Division 1; Class III, Division 2; and Zone 22 hazardous (classified)
locations, the combination shall be designed to ensure that current cannot be ruptured at the separable
electrical connections while energized parts are exposed.
This standard also references requirements for Class I; Division 1 explosion-proof enclosures marked
Type 7 and Class II, Division 1 dust-ignition-proof enclosures marked Type 9. The reference requirements
are in accordance with ANSI/UL 1203, ExplosionProof and Dust-IgnitionProof Electrical Equipment for
Use in Hazardous (Classified) Locations (UL 1203), with the associated area classifications and
installation requirements in accordance with NEC®.
This standard supplements the requirements for enclosures that are contained in the individual product
standards.
This standard does not cover the requirements for the protection of the enclosed equipment against
conditions such as condensation, gas vapor ignition, thermal damage, icing, corrosion, or contamination
that may occur within the enclosure or that may enter via conduit or unsealed openings.
This standard does not cover protection of personnel from contact with enclosed electrical equipment
where the enclosures or equipment are incompletely installed or where enclosed electrical equipment has
been rendered accessible for servicing, maintenance, testing, troubleshooting, internal measurements,
calibration, or by damage.
A product that contains features, characteristics, components, materials, or systems new or different from
those in use when the standard was developed (and that involves a risk of fire, electric shock, or injury to
persons) shall be evaluated using the appropriate additional component and end-product requirements as
determined necessary to maintain the level of safety for the user of the product as originally anticipated
by the intent of this standard.

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