Journeyman Electrician’s Exam Journeyman Electrician's Low Voltage Systems 1 — Questions and Answers
Question 1: According to NEC Article 725, which class of circuit is characterized by inherently limited power output, making it safe due to low energy levels?
- Class 1
- Class 2 (Correct answer)
- Class 3
- Class 4
Correct answer: Class 2
Class 2 circuits are defined by their limited power output, making them inherently safe with minimal fire and shock hazards per NEC Article 725.
Question 2: What is the maximum voltage permitted for a Class 1 remote-control or signaling circuit per NEC Article 725?
- 150 volts
- 300 volts
- 600 volts (Correct answer)
- 1000 volts
Correct answer: 600 volts
NEC 725.41 limits Class 1 circuits to 600 volts, placing them in the same general voltage range as standard power circuits.
Question 3: Under NEC Article 725, Class 2 and Class 3 conductors shall NOT be placed in the same cable, enclosure, or raceway as which of the following?
- Fire alarm wiring
- Communications wiring
- Class 1 circuit conductors (Correct answer)
- Telephone cables
Correct answer: Class 1 circuit conductors
Class 2 and Class 3 conductors must be separated from Class 1 circuits because Class 1 operates at higher power levels that could damage or compromise low-voltage wiring.
Question 4: Which cable designation is listed under NEC Article 725 for Class 2 circuits in a general (non-plenum, non-riser) installation?
- CM
- CL2 (Correct answer)
- CMP
- CMG
Correct answer: CL2
CL2 is the listed cable type for Class 2 circuit applications in general (non-plenum, non-riser) installations per NEC Article 725.
Question 5: A Class 3 circuit differs from a Class 2 circuit primarily because Class 3 circuits:
- Allow higher voltages but with limited current output (Correct answer)
- Require a larger minimum conductor size
- Must always be installed in conduit
- Have no power limitations whatsoever
Correct answer: Allow higher voltages but with limited current output
Class 3 circuits allow higher voltages than Class 2 (up to 150V) while still limiting current output, making them suitable for applications requiring voltages above 30V.
Question 6: Per NEC Article 725, Class 1 circuit conductors must be protected by overcurrent protection in accordance with:
- Article 240 with a maximum of 7 amperes
- NEC 725.43 based on conductor ampacity (Correct answer)
- GFCI devices rated for low-voltage circuits
- AFCI devices listed for Class 1 use
Correct answer: NEC 725.43 based on conductor ampacity
NEC 725.43 specifies overcurrent protection for Class 1 circuits, requiring protection not to exceed the ampacity of the conductors.
Question 7: Which of the following is a common example of a Class 2 low-voltage circuit typically installed by journeyman electricians?
- Fire alarm initiating device circuits
- Residential doorbell and chime systems (Correct answer)
- Emergency lighting branch circuits
- 120-volt landscape lighting circuits
Correct answer: Residential doorbell and chime systems
Residential doorbell and chime systems operate at 16-24V AC with limited power from a listed transformer, classifying them as Class 2 circuits under NEC Article 725.
