Definitions Applicable to 29 CFR 1926 Subpart K cont'd

DOE-HDBK-1092-2004

1. combustible dust will not normally be in suspension in the air in quantities sufficient to

produce explosive or ignitable mixtures, and dust accumulations are normally insufficient

to interfere with the normal operation of electrical equipment or other apparatus; or

2. dust may be in suspension in the air as a result of infrequent malfunctioning of handling

or processing equipment, and dust accumulations resulting therefrom may be ignitable

by abnormal operation or failure of electrical equipment or other apparatus.

NOTE: This classification includes locations where dangerous concentrations of suspended

dust would not be likely but where dust accumulations might form on or in the vicinity of

electric equipment. These areas may contain equipment from which appreciable quantities

of dust would escape under abnormal operating conditions or be adjacent to a Class II

Division 1 location, as described above, into which an explosive or ignitable concentration of

dust may be put into suspension under abnormal operating conditions.

Class III locations--Class III locations are those that are hazardous because of the presence of

easily ignitable fibers or flyings but in which such fibers or flyings are not likely to be in

suspension in the air in quantities sufficient to produce ignitable mixtures. Class l l l locations

include the following:

a. Class III, Division I--A Class III, Division l location is a location in which easily ignitable

fibers or materials producing combustible flyings are handled, manufactured, or used.

NOTE: Easily ignitable fibers and flyings include rayon, cotton (including cotton linters and

cotton waste), sisal or henequen, istle, jute, hemp, tow, cocoa fiber, oakum, baled waste

kapok, Spanish moss, excelsior, sawdust, woodchips, and other material of similar nature.

b. Class III, Division 2--A Class 111, Division 2 location is a location in which easily ignitable

fibers are stored or handled, except in process of manufacture.

Collector ring--A collector ring is an assembly of slip rings for transferring electrical energy

from a stationary to a rotating member.

Concealed--Rendered inaccessible by the structure or finish of the building. Wires in concealed

raceways are considered concealed, even though they may become accessible by withdrawing

them. [See "Accessible. (As applied to wiring methods.)"]

Conductor--

a. Bare--A conductor having no covering or electrical insulation whatsoever.

b. Covered--A conductor encased within material of composition or thickness that is not

recognized as electrical insulation.

c. Insulated--A conductor encased within material of composition and thickness that is

recognized as electrical insulation.

Controller--A device or group of devices that serves to govern, in some predetermined

manner, the electric power delivered to the apparatus to which it is connected.

Covered conductor--See "Conductor."

B-26