Electrical Systems & Wiring Flashcards
7 cards from real CPT practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Electrical Systems & Wiring flashcards as text
What is the primary reason process technicians must de-energize and lockout/tagout equipment before performing electrical maintenance?
Answer: To prevent unexpected energization that could cause injury or death
LOTO procedures ensure all energy sources are isolated and cannot be re-energized while workers are exposed to hazardous electrical energy.
Which type of electrical enclosure rating is required for equipment installed in locations where water jets may be directed at the enclosure?
Answer: NEMA 4
NEMA 4 enclosures are watertight and protect against windblown dust, rain, and hose-directed water.
A process technician notices a motor running hotter than normal but not tripping its overload. What is the most likely cause?
Answer: One phase of a three-phase supply has lost continuity (single phasing)
Single phasing forces the remaining two phases to carry excess current, causing the motor to overheat without necessarily tripping the overload.
What does an ammeter clamp measure without breaking the circuit?
Answer: Current flowing through a conductor by detecting its magnetic field
A clamp meter uses a current transformer around the conductor to measure current through electromagnetic induction.
In a process control loop, what type of cable is used to minimize electrical noise interference on analog signals?
Answer: Twisted-pair shielded cable
Twisted-pair shielded cable cancels electromagnetic interference through the twisting effect and blocks external noise via the shield.
What is the purpose of a disconnect switch located at a motor or piece of equipment?
Answer: To provide a means to locally isolate the equipment from its power source
A local disconnect allows safe isolation of equipment for maintenance without traveling to the main electrical panel.
Which of the following is the correct way to verify a circuit is de-energized before working on it?
Answer: Use a non-contact voltage tester or voltmeter to verify absence of voltage
Always test for the absence of voltage with a calibrated instrument after locking out; visual checks alone are insufficient.