E2 Hazardous (Classified) Locations 4

Question 1

Which NEC article governs Class III hazardous locations involving ignitable fibers or flyings?

Accepted Answer

Article 503

Answer

NEC Article 503 covers Class III locations where easily ignitable fibers or flyings are handled, manufactured, or used.

Question 2

What does the temperature class (T-code) on explosion-proof equipment indicate?

Accepted Answer

The maximum surface temperature the equipment can reach

Answer

The T-code (T1 through T6) indicates the maximum surface temperature the equipment can reach during operation, which must not exceed the ignition temperature of the hazardous gas or vapor present.

Question 3

In a Class I, Division 2 location, standard open-type motors are permitted under which condition?

Accepted Answer

When the motor does not have sliding contacts or switching mechanisms inside the motor enclosure

Answer

In Class I, Division 2, squirrel-cage induction motors without brushes, switching mechanisms, or similar arc-producing devices inside the enclosure may be used.

Question 4

The zone classification system for Class I locations (Zone 0, 1, 2) was derived from which standard?

Accepted Answer

IEC (International Electrotechnical Commission) standards

Answer

The Zone classification system was derived from IEC (International Electrotechnical Commission) standards and was incorporated into the NEC as an alternative to the Division system.

Question 5

What is the minimum sealing compound fill requirement for conduit seals in Class I locations?

Accepted Answer

Three-eighths of the internal diameter of the conduit but not less than 5/8 inch

Answer

Per NEC Section 501.15, the sealing compound must have a minimum thickness equal to the trade size of the conduit but not less than 5/8 inch.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

E2 Hazardous (Classified) Locations 4