Exam 20: Hazardous Locations

A Group A atmosphere contains________ .

________locations are considered to be the most hazardous.

Some types of explosionproof enclosures are designed to be drilled and tapped in the field. When this is done, at least________ full threads should be engaged between the conduit and the enclosure.

What do Group C and D atmospheres encompass?

What conditions are required for flexible cords and attachment plugs to be used in hazardous areas?

What is the difference between Division 1 and Division 2 hazardous locations?

As a general rule, equipment installed in a Class II location must be ________.

Intrinsically safe equipment and circuits operate________ .

What is the hazard level of an aircraft hangar?

When horizontal seals are installed,________fiber dams must be used.

When circuit breakers are installed in Class I locations, they must be________ .

In general, the floor area of a garage, up to a level of 18 in. (450 mm) above the floor, is considered to be a________ location.

Class III locations are areas that contain combustible________ .

If it is necessary to remove a substance from the surface of an explosionproof enclosure that cannot be cleaned with solvent, use________ .

If a stem is longer than________in., lateral braces must be placed within 12 in. (300 mm) of the luminaire, or an explosionproof flexible coupling must be used within 12 in. (300 mm) of the junction box.

________are used to minimize the passage of gas and to prevent the passage of flame through the conduit.

The________ rating indicates the maximum operating temperature of a luminaire.

To help prevent condensation, some vertical seals are designed with________ .

A Group E atmosphere contains ________.

Describe the mating surfaces of explosionproof equipment.