Features and Test Criteria

DOE-HDBK-1092-2004

5.7.2

FEATURES AND TEST CRITERIA

When completely and properly installed, Type 7 enclosures:

1. Provide to a hazardous gas environment a degree of protection from an internal explosion or

from operation of internal equipment

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

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

heat-simulating equipment is operated at rated load

3. Withstand a series of internal explosion design tests:

a. That determine the maximum pressure effects of the gas mixture

b. That determine propagation effects of the gas mixtures.

4. Withstand, without rupture or permanent distortion, an internal hydrostatic design test based

on the maximum internal pressure obtained during explosion tests and on a specified safety

factor

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

5.8

TYPE 8 ENCLOSURES

Type 8 enclosures are designed for indoor or outdoor use in locations classified as Class I

Groups A, B, C, or D as defined in the NEC.

5.8.1

DESCRIPTION AND APPLICATION

Type 8 enclosures and enclosed devices are arranged such that all arcing contacts,

connections, and any parts that could cause arcing are immersed in oil. Arcing is confined under

the oil such that it will not ignite an explosive mixture of the specified gases in internal spaces

above the oil or in the atmosphere surrounding the enclosure. Enclosed heat-generating

devices shall not cause external surfaces to reach temperatures capable of igniting explosive

gas-air mixtures in the surrounding atmosphere. Enclosures shall meet operation and

temperature-design tests. Enclosures intended for outdoor use shall also meet the rain test (See

#4 in Section 5.8.2).

5.8.2

FEATURES AND TEST CRITERIA

When completely and properly installed, Type 8 enclosures:

1. Provide, by oil immersion, a degree of protection to a hazardous gas environment from

operation of internal equipment

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

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

equipment is at rated load

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