[Code of Federal Regulations]
[Title 29, Volume 8]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 29CFR1926.407]

[Page 260-261]
 
                             TITLE 29--LABOR
 
CHAPTER XVII--OCCUPATIONAL SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT 
                                OF LABOR
 
PART 1926_SAFETY AND HEALTH REGULATIONS FOR CONSTRUCTION--Table of Contents
 
                          Subpart K_Electrical
 
Sec. 1926.407  Hazardous (classified) locations.

    (a) Scope. This section sets forth 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. 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 l
Class III, Division 2

    For definitions of these locations see Sec. 1926.449. All 
applicable requirements in this subpart apply to all 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 
approved as intrinsically safe or approved for the hazardous 
(classified) location or safe 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 is permitted in any hazardous (classified) location 
included in its listing or labeling.
    (2) Approved for the hazardous (classified) location--(i) General. 
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) Marking. Equipment shall not be used unless it is marked to 
show the class, group, and operating temperature or temperature range, 
based on operation in a 40-degree C ambient, for which it is approved. 
The temperature marking shall not exceed the ignition temperature of the 
specific gas, vapor, or dust 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 fitting) and equipment of the heat-producing type 
having a maximum temperature of not more than 100 degrees C (212 degrees 
F) need not

[[Page 261]]

have a marked operating temperature or temperature range.
    (B) Fixed lighting fixtures marked for use only in Class I, Division 
2 locations 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 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.

[51 FR 25318, July 11, 1986, as amended at 61 FR 5510, Feb. 13, 1996]