Definitions Applicable to 29 CFR 1910.269 cont'd

DOE-HDBK-1092-2004

Energy isolating device--A physical device that prevents the transmission or release of

energy, including, but not limited to, the following: a manually operated electric circuit breaker,

a disconnect switch, a manually operated switch, a slide gate, a slip blind, a line valve, blocks,

and any similar device with a visible indication of the position of the device. (Push buttons,

selector switches, and other control-circuit-type devices are not energy isolating devices.)

Energy ,source--Any electrical, mechanical, hydraulic, pneumatic, chemical, nuclear, thermal,

or other energy source that could cause injury to personnel.

Equipment (electric)--A general term including material, fittings, devices, appliances, fixtures,

apparatus, and the like used as part of or in connection with an electrical installation.

Exposed--Not isolated or guarded.

Ground--A conducting connection, whether intentional or accidental, between an electric

circuit or equipment and the earth, or to some conducting body that serves in place of the

earth.

Grounded--Connected to earth or to some conducting body that serves in place of the earth.

Guarded--Covered, fenced, enclosed, or otherwise protected, by means of suitable covers or

casings, barrier rails or screens, mats, or platforms, designed to minimize the possibility,

under normal conditions, of dangerous approach or accidental contact by persons or objects.

NOTE: Wires which are insulated, but not otherwise protected, are not considered as

guarded.

Hazardous atmosphere means an atmosphere that may expose employees to the risk of

death, incapacitation, impairment of ability to self--rescue (that is, escape unaided from an

enclosed space), injury, or acute illness from one or more of the following causes:

1. Flammable gas, vapor, or mist in excess of 10 percent of its lower flammable limit (LFL);

2. Airborne combustible dust at a concentration that meets or exceeds its LFL;

NOTE: This concentration may be approximated as a condition in which the dust obscures

vision at a distance of 5 feet (1.52 m) or less.

3. Atmospheric oxygen concentration below 19.5 percent or above 23.5 percent;

4. Atmospheric concentration of any substance for which a dose or a permissible exposure

limit is published in Subpart G, Occupational Health and Environmental Control, or in

Subpart Z, Toxic and Hazardous Substances, of this Part and which could result in

employee exposure in excess of its dose or permissible exposure limit; Note: An

atmospheric concentration of any substance that is not capable of causing death,

incapacitation, impairment of ability to self-rescue, injury, or acute illness due to its health

effects is not covered by this provision.

5. Any other atmospheric condition that is immediately dangerous to life or health.

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