Circuit breaker

DOE-HDBK-1092-2004

Certified--Equipment is "certified" if it (a) has been tested and found by a nationally recognized

testing laboratory to meet nationally recognized standards or to be safe for use in a specified

manner, or (b) is of a kind whose production is periodically inspected by a nationally recognized

testing laboratory, and (c) it bears a label, tag, or other record of certification.

Circuit breaker--

(600 volts nominal, or less). A device designed to open and close a circuit by nonautomatic

means and to open the circuit automatically on a predetermined overcurrent without injury to

itself when properly applied within its rating.

ii. (Over 600 volts, nominal). A switching device capable of making, carrying, and breaking

currents under normal circuit conditions, and also making, carrying for a specified time, and

breaking currents under specified abnormal circuit conditions, such as those of short circuit.

Class I locations--Class I locations are those in which flammable gases or vapors are or may

be present in the air in quantities sufficient to produce explosive or ignitable mixtures. Class I

locations include the following:

Class I, Division l. A Class I, Division I location is a location:

1. in which hazardous concentrations of flammable gases or vapors may exist under

normal operating conditions; or

2. in which hazardous concentrations of such gases or vapors may exist frequently

because of repair or maintenance operations or because of leakage; or in which

breakdown or faulty operation of equipment or processes might release hazardous

concentrations of flammable gases or vapors, and might also cause simultaneous failure

of electric equipment.

NOTE: This classification usually includes locations where volatile flammable liquids or liquefied

flammable gases are transferred from one container to another; interiors of spray booths

and areas in the vicinity of spraying and painting operations where volatile flammable

solvents are used; locations containing open tanks or vats of volatile flammable liquids;

drying rooms or compartments for the evaporation of flammable solvents; locations

containing fat and oil extraction equipment using volatile flammable solvents; portions of

cleaning and dyeing plants where flammable liquids are used; gas generator rooms and

other portions of gas manufacturing plants where flammable gas may escape; inadequately

ventilated pump rooms for flammable gas or for volatile flammable liquids; the interiors of

refrigerators and freezers in which volatile flammable materials are stored in open, lightly

stoppered, or easily ruptured containers; and all other locations where ignitable

concentrations of flammable vapors or gases are likely to occur in the course of normal

operations.

ii. Class I, Division 2. A Class I, Division 2 location is a location:

a. in which volatile flammable liquids or flammable gases are handled, processed, or used,

but in which the hazardous liquids, vapors, or gases will normally be confined within

closed containers or closed systems from which they can escape only in case of

accidental rupture or breakdown of such containers or systems, or in case of abnormal

operation of equipment; or

B-5