[Title 29 CFR 1910.307]
[Code of Federal Regulations (annual edition) - July 1, 2002 Edition]
[Title 29 - LABOR]
[Subtitle B - Regulations Relating to Labor (Continued)]
[Chapter Xvii - OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT]
[Part 1910 - OCCUPATIONAL SAFETY AND HEALTH STANDARDS]
[Subpart S - Electrical]
[Sec. 1910.307 - Hazardous (classified) locations.]
[From the U.S. Government Printing Office]


29LABOR52002-07-012002-07-01false1910.307Sec. 1910.307LABORRegulations Relating to Labor (Continued)OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENTOCCUPATIONAL SAFETY AND HEALTH STANDARDSElectrical
Sec. 1910.307  Hazardous (classified) locations.

    (a) Scope. This section covers the requirements for electric 
equipment and wiring in locations which are classified depending on the 
properties of the flammable vapors, liquids or gases, or combustible 
dusts or fibers which may be present therein and the likelihood that a 
flammable or combustible concentration or quantity is present. Hazardous 
(classified) locations may be found in occupancies such as, but not 
limited to, the following: aircraft hangars, gasoline dispensing and 
service stations, bulk storage plants for gasoline or other volatile 
flammable liquids, paint-finishing process plants, health care 
facilities, agricultural or other facilities where excessive combustible 
dusts may be present, marinas, boat yards, and petroleum and chemical 
processing plants. Each room, section or area shall be considered 
individually in determining its classification. These hazardous 
(classified) locations are assigned six designations as follows:

Class I, Division 1
Class I, Division 2
Class II, Division 1
Class II, Division 2
Class III, Division 1
Class III, Division 2


For definitions of these locations see Sec. 1910.399(a). All applicable 
requirements in this subpart shall apply to hazardous (classified) 
locations, unless modified by provisions of this section.
    (b) Electrical installations. Equipment, wiring methods, and 
installations of equipment in hazardous (classified) locations shall be 
intrinsically safe, approved for the hazardous (classified) location, or 
safe or for the hazardous (classified) location. Requirements for each 
of these options are as follows:
    (1) Intrinsically safe. Equipment and associated wiring approved as 
intrinsically safe shall be permitted in any hazardous (classified) 
location for which it is approved.
    (2) Approved for the hazardous (classified) location. (i) Equipment 
shall be approved not only for the class of location but also for the 
ignitible or combustible properties of the specific gas, vapor, dust, or 
fiber that will be present.
    Note: NFPA 70, the National Electrical Code, lists or defines 
hazardous gases, vapors, and dusts by ``Groups'' characterized by their 
ignitible or combustible properties.
    (ii) Equipment shall be marked to show the class, group, and 
operating temperature or temperature range, based on operation in a 40 
degrees C ambient, for which it is approved. The temperature marking may 
not exceed the ignition temperature of the specific gas or vapor to be 
encountered. However, the following provisions modify this marking 
requirement for specific equipment:
    (A) Equipment of the non-heat-producing type, such as junction 
boxes, conduit, and fittings, and equipment of the heat-producing type 
having a maximum temperature not more than 100 degrees C (212 degrees F) 
need not have a marked operating temperature or temperature range.
    (B) Fixed lighting fixtures marked for use in Class I, Division 2 
locations only, need not be marked to indicate the group.
    (C) Fixed general-purpose equipment in Class I locations, other than 
lighting fixtures, which is acceptable for use in Class I, Division 2 
locations need not be marked with the class, group, division, or 
operating temperature.
    (D) Fixed dust-tight equipment, other than lighting fixtures, which 
is acceptable for use in Class II, Division 2 and Class III locations 
need not be marked with the class, group, division, or operating 
temperature.
    (3) Safe for the hazardous (classified) location. Equipment which is 
safe for the location shall be of a type and design which the employer 
demonstrates will provide protection from the hazards arising from the 
combustibility and flammability of vapors, liquids, gases, dusts, or 
fibers.
    Note: The National Electrical Code, NFPA 70, contains guidelines for 
determining the type and design of equipment and installations which 
will meet this requirement. The guidelines of this document address 
electric wiring, equipment, and systems installed in hazardous 
(classified) locations and contain specific provisions for the 
following: wiring methods, wiring connections; conductor insulation, 
flexible cords, sealing and drainage, transformers, capacitors, 
switches, circuit

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breakers, fuses, motor controllers, receptacles, attachment plugs, 
meters, relays, instruments, resistors, generators, motors, lighting 
fixtures, storage battery charging equipment, electric cranes, electric 
hoists and similar equipment, utilization equipment, signaling systems, 
alarm systems, remote control systems, local loud speaker and 
communication systems, ventilation piping, live parts, lightning surge 
protection, and grounding. Compliance with these guidelines will 
constitute one means, but not the only means, of compliance with this 
paragraph.
    (c) Conduits. All conduits shall be threaded and shall be made 
wrench-tight. Where it is impractical to make a threaded joint tight, a 
bonding jumper shall be utilized.
    (d) Equipment in Division 2 locations. Equipment that has been 
approved for a Division 1 location may be installed in a Division 2 
location of the same class and group. General-purpose equipment or 
equipment in general-purpose enclosures may be installed in Division 2 
locations if the equipment does not constitute a source of ignition 
under normal operating conditions.

[46 FR 4056, Jan. 16, 1981; 46 FR 40185, Aug. 7, 1981]