Hazardous Location Wiring Flashcards
7 cards from real CEI 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 Location Wiring flashcards as text
For Class II hazardous locations, dust-tight enclosures are required in Division 2. What is the primary purpose of this requirement?
Answer: To prevent dust from entering and accumulating on live parts
Dust-tight enclosures in Class II, Division 2 locations prevent combustible dust accumulation on live parts where arcs or high temperatures could cause ignition.
Which condition must be met before opening explosion-proof equipment in a Class I, Division 1 location while energized?
Answer: Both A and C
Explosion-proof enclosures in Division 1 locations must either be de-energized or the area verified as gas-free before opening, per standard safety practice and NEC requirements.
In a Class I area, what is the function of a 'breather' or 'drain' fitting on explosion-proof equipment?
Answer: To allow moisture to escape while maintaining the explosion-proof rating
Explosion-proof breather/drain fittings allow condensation to drain and pressure equalization while preventing flame propagation and maintaining the Class I rating.
Under NEC 505, Zone 1 is most comparable to which Division classification?
Answer: Part of Division 1 and part of Division 2
Zone 1 (where flammable gas is likely during normal operations) overlaps with the less severe portion of Division 1 and includes some scenarios covered by Division 2.
When installing conduit in a Class I, Division 1 location, horizontal runs of conduit must have a drain seal when the conduit length exceeds what threshold?
Answer: 10 feet
Per NEC 501.15(F), drain seals or equivalent drainage provisions are required in horizontal conduit runs exceeding 10 feet where condensation could accumulate.
Which of the following describes a 'nonincendive' circuit as used in Class I, Division 2 locations?
Answer: A circuit incapable of releasing sufficient energy to cause ignition under normal conditions
A nonincendive circuit is one where the electrical energy available is insufficient to ignite a specific hazardous atmosphere under normal (non-fault) operating conditions.
What does the NEC require for grounding and bonding of metal conduit systems in Class I, Division 1 locations?
Answer: Bonding jumpers around all threaded connections to ensure electrical continuity
NEC 501.30 requires bonding jumpers around all conduit connections in Class I, Division 1 locations to ensure continuous low-impedance grounding paths and prevent arcing at loose fittings.