Type 9 Enclosures

DOE-HDBK-1092-2004

3. Withstand a series of operation design tests with oil levels arbitrarily reduced and

with flammable gas-air mixtures introduced above the oil

4. When intended for installation outdoors, exclude water when subjected to a water spray

design test simulating a beating rain

5. Are marked with the appropriate class and groups for which they have been qualified

5.9

TYPE 9 ENCLOSURES

Type 9 enclosures are designed for indoor use in locations classified as Class II Groups E or G,

as defined in the NEC.

5.9.1

DESCRIPTION AND APPLICATION

Type 9 enclosures shall prevent the entrance of dust. Enclosed heat-generating devices shall

not cause external surfaces to reach temperatures capable of igniting or discoloring dust on the

enclosure or igniting dust-air mixtures in the surrounding atmosphere. Enclosures shall meet

dust-penetration and temperature-design tests and prevent aging of gaskets (if used).

5.9.2

FEATURES AND TEST CRITERIA

When completely and properly installed, Type 9 enclosures:

1. Provide a degree of protection to a hazardous dust environment from operation of internal

equipment

2. Do not develop surface temperatures that exceed prescribed limits for the group

corresponding to the atmospheres for which the enclosure is intended when internal

equipment is operated at rated load

3. Withstand a series of operation design tests while exposed to a circulating dust-air mixture

to verify that dust does not enter the enclosure and that operation of devices does not cause

ignition of surrounding atmosphere

4. Are marked with the appropriate class and groups for which they have been qualified

5.10 UNDERGROUND FACILITIES

Underground facilities consist of electrical equipment and wiring installed in underground

locations. Working conditions underground can present to electrical workers hazards different

from those presented above ground. This section aids in dealing with such problems.

Electrical work in support of construction of mines, shafts, and underground utilities shall be

performed by qualified workers who must meet the requirements in Section 2.8, 30 CFR 75.153

and 77.103. Only those workers shall install equipment and conductors within the construction

activity.

Note: DOE does not engage in "mining" as mining is the extraction of minerals for profit.

However, the codes related to mining (30 CFR 57, 75, and 77) should be followed, where

applicable, along with the OSHA regulations set forth in 29 CFR 1910 and 1926.

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