CAT CAT Electrical and Wiring Fundamentals 1 — Questions and Answers
Question 1: What wire gauge is most commonly used for low-voltage alarm system wiring?
- 22 AWG (Correct answer)
- 10 AWG
- 14 AWG
- 6 AWG
Correct answer: 22 AWG
22 AWG is the standard low-voltage wire gauge used in most residential and commercial alarm system installations.
Question 2: What is the purpose of an end-of-line (EOL) resistor in a security alarm circuit?
- Supervise the circuit so the panel can detect a cut or shorted wire (Correct answer)
- Increase voltage on the detection loop
- Reduce current draw from the panel
- Protect the panel from power surges
Correct answer: Supervise the circuit so the panel can detect a cut or shorted wire
An EOL resistor allows the panel to continuously monitor the circuit integrity and distinguish between a fault, tamper, or alarm condition.
Question 3: Which type of wiring configuration is required by NFPA 72 for Class A fire alarm circuits?
- Loop/return path so the circuit survives a single open fault (Correct answer)
- Star topology from a central hub
- Daisy chain with no return
- Home run to each device
Correct answer: Loop/return path so the circuit survives a single open fault
Class A wiring provides a redundant return path so the system continues to operate even when one section of wire is broken.
Question 4: What does a supervised circuit in a security alarm system detect?
- Wire cuts and short circuits (Correct answer)
- Only motion sensor activity
- Power grid fluctuations
- Battery voltage levels
Correct answer: Wire cuts and short circuits
A supervised circuit continuously monitors wiring integrity and alerts the panel if the wire is cut (open) or shorted.
Question 5: Why is shielded cable recommended for alarm keypad wiring?
- To reduce electromagnetic interference that could cause false signals (Correct answer)
- To increase the wire's current capacity
- To comply with NEC Article 225
- To improve physical strength of the wire run
Correct answer: To reduce electromagnetic interference that could cause false signals
Shielded cable blocks EMI from nearby electrical sources, preventing corrupted data signals on sensitive alarm communication lines.
Question 6: How far must alarm low-voltage wiring be separated from high-voltage (120V+) electrical wiring when run in parallel?
- At least 2 inches (Correct answer)
- At least 12 inches
- They may touch if both are in conduit
- No separation is required
Correct answer: At least 2 inches
NEC Article 760 requires low-voltage alarm wiring to maintain at least 2 inches of separation from power conductors to prevent induced interference.
CAT CAT Electrical and Wiring Fundamentals 1
What wire gauge is most commonly used for low-voltage alarm system wiring?