Free E2 Hazardous (Classified) Locations Questions and Answers 1

Question 1

According to NEC Article 500, a Class I, Division 1 location is a location in which ignitable concentrations of flammable gases or vapors can exist under which condition?

Accepted Answer

Under normal operating conditions.

Answer

NEC 500.5(B)(1) defines a Class I, Division 1 location as one where ignitable concentrations of flammable gases, vapors, or liquids can exist under normal operating conditions. Division 2 locations are those where such concentrations are present only under abnormal conditions, such as container failure or equipment breakdown.

Question 2

In a Class I, Division 1 location, a conduit seal shall be installed within what distance of a terminal or junction box that contains a switch, circuit breaker, or other arcing device?

Accepted Answer

18 inches

Answer

NEC 501.15(A)(1) requires that in Class I, Division 1 locations, a conduit seal shall be placed within 18 inches of any enclosure that contains arcing or high-temperature devices. This seal is critical to prevent an explosion from propagating through the conduit system.

Question 3

What does the temperature marking, or 'T-Code', on a piece of equipment used in a hazardous location signify?

Accepted Answer

The maximum surface temperature the equipment will develop.

Answer

As per NEC 500.8(C), the T-Code indicates the maximum surface temperature the equipment can reach during operation. This temperature must be less than the autoignition temperature of the specific hazardous substance present in the atmosphere to prevent ignition.

Question 4

Which of the following wiring methods is permitted in a Class II, Division 1 location?

Accepted Answer

Threaded rigid metal conduit (RMC)

Answer

NEC 502.10(A) lists the permitted wiring methods for Class II, Division 1 locations, which involve combustible dust. Threaded rigid metal conduit (RMC) or intermediate metal conduit (IMC) are primary methods to prevent dust ingress and contain any potential internal issues.

Question 5

The fundamental principle of an intrinsically safe system as defined in NEC Article 504 is to:

Accepted Answer

Limit the electrical energy to a level below that required to ignite a hazardous atmosphere.

Answer

NEC 504.2 defines an intrinsically safe circuit as one in which any spark or thermal effect is incapable of causing ignition of a mixture of flammable or combustible material in air. This is achieved by limiting the electrical energy (voltage and current) to levels below what is needed to cause ignition.

(E2) E2 Commercial Electrical Inspector Practice Test

(E2) E2 Commercial Electrical Inspector Practice Test

Free E2 Hazardous (Classified) Locations Questions and Answers 1