CEI Electrical System Components 3 — Questions and Answers
Question 1: Which insulation type is rated for use in wet locations and has a 90°C temperature rating?
- Type TW
- Type THHN
- Type THWN-2 (Correct answer)
- Type RHH
Correct answer: Type THWN-2
Type THWN-2 is rated for wet locations with a 90°C temperature rating, making it suitable for conduit in damp or wet environments.
Question 2: A transformer's kVA rating represents which of the following?
- Its maximum power output in kilowatts
- Its apparent power capacity (Correct answer)
- Its efficiency percentage
- Its short-circuit current rating
Correct answer: Its apparent power capacity
kVA (kilovolt-amperes) represents the apparent power rating of a transformer, which is the product of voltage and current without regard to power factor.
Question 3: What component is used to connect a grounding electrode system to the service equipment?
- Service entrance conductor
- Grounding electrode conductor (GEC) (Correct answer)
- Equipment grounding conductor
- Bonding jumper
Correct answer: Grounding electrode conductor (GEC)
The grounding electrode conductor (GEC) connects the grounding electrode system (such as a ground rod) to the service equipment.
Question 4: Which type of switch is used to control a single light fixture from two different locations?
- Single-pole switch
- Three-way switch (Correct answer)
- Four-way switch
- Double-pole switch
Correct answer: Three-way switch
Three-way switches are used in pairs to control a single load from two separate locations, such as both ends of a staircase.
Question 5: What is the minimum cover requirement for direct-buried Schedule 80 PVC conduit under a residential driveway?
- 6 inches
- 12 inches (Correct answer)
- 18 inches
- 24 inches
Correct answer: 12 inches
NEC Table 300.5 requires a minimum 12-inch cover for Schedule 80 PVC conduit under a residential driveway.
Question 6: A GFCI device is designed to trip when a ground fault current reaches approximately what level?
- 1 milliamp
- 5 milliamps (Correct answer)
- 15 milliamps
- 30 milliamps
Correct answer: 5 milliamps
GFCI devices are designed to trip at approximately 4-6 milliamps (nominally 5 mA) to protect against electrocution.
Question 7: When installing a meter socket, the service conductors entering from the utility are referred to as:
- Feeder conductors
- Service-entrance conductors (Correct answer)
- Branch circuit conductors
- Ungrounded conductors only
Correct answer: Service-entrance conductors
The conductors from the utility connection point to the service disconnect are classified as service-entrance conductors.
CEI Electrical System Components 3
Which insulation type is rated for use in wet locations and has a 90°C temperature rating?