Hazardous (Classified) Locations Flashcards
7 cards from real E2 practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Hazardous (Classified) Locations flashcards as text
Which of the following gases is classified in Group B in Class I hazardous locations?
Answer: Hydrogen
Hydrogen is classified in Group B of Class I hazardous locations, along with gases that have similar explosion characteristics.
Purged and pressurized enclosures used in hazardous locations must comply with which standard?
Answer: NFPA 496
NFPA 496 is the standard for purged and pressurized enclosures for electrical equipment in hazardous locations.
In Class I, Division 2 locations, which of the following wiring methods is NOT permitted?
Answer: Electrical metallic tubing (EMT)
Electrical metallic tubing (EMT) is not permitted in Class I, Division 2 locations because it uses set-screw or compression fittings that do not provide adequate protection against the hazardous atmosphere.
When installing explosion-proof equipment, threaded conduit connections must have a minimum of how many engaged threads?
Answer: 5 threads
NEC Section 501.10 requires threaded conduit connections to explosion-proof enclosures to have at least 5 fully engaged threads to maintain the explosion-proof integrity of the joint.
Which protection concept uses oil immersion to prevent ignition of a surrounding hazardous atmosphere?
Answer: Oil immersion (Ex o)
Oil immersion (Ex o) is a protection technique where electrical equipment or parts of equipment are submerged in oil to prevent ignition of the surrounding atmosphere.
A commercial dry cleaning facility where flammable solvents are used would require the area near solvent-handling equipment to be classified as:
Answer: Class I, Division 1
Areas in dry cleaning facilities where flammable solvents are used or handled normally are classified as Class I, Division 1 due to the continuous presence of flammable vapors during operations.
Under the NEC, who is responsible for classifying hazardous locations in a facility?
Answer: A qualified person with expertise in the relevant flammable or combustible materials
Per NEC Section 500.4, the classification of hazardous locations must be performed by a qualified person(s) knowledgeable in the specific flammable or combustible materials present.