CAT Alarm Technician Wiring & Circuits 3 — Questions and Answers
Question 1: A normally closed (NC) contact connected across a zone loop WITHOUT an end-of-line resistor would cause the panel to:
- Show a normal supervisory state
- Report a trouble condition (Correct answer)
- Report an alarm condition
- Report a ground fault
Correct answer: Report a trouble condition
Without the EOL resistor the panel cannot distinguish between a resting NC contact and a shorted wire, triggering a trouble indication.
Question 2: What is the MAXIMUM recommended total loop resistance for most conventional initiating device circuits?
- 10 ohms
- 25 ohms
- 50 ohms (Correct answer)
- 100 ohms
Correct answer: 50 ohms
Most panels specify a maximum zone loop resistance of 50 ohms; exceeding this can prevent reliable alarm detection.
Question 3: Which cable listing is required for alarm wiring run in a plenum air-handling space?
- CM (Communications)
- CL2 (Class 2 general)
- FPL (Fire Power Limited)
- FPLP (Fire Power Limited Plenum) (Correct answer)
Correct answer: FPLP (Fire Power Limited Plenum)
FPLP-rated cable has low-smoke, low-flame characteristics required for installation in air-handling plenums per NFPA 72 and NEC Article 760.
Question 4: When daisy-chaining motion detectors on a single zone, the technician should wire the alarm outputs in:
- Parallel (NO contacts in parallel)
- Series (NC contacts in series) (Correct answer)
- A star topology with individual home runs
- Alternating NO and NC configuration
Correct answer: Series (NC contacts in series)
NC contacts wired in series form a continuous loop; any detector opening the contact breaks the loop and triggers an alarm.
Question 5: The purpose of a double-end-of-line (DEOL) resistor configuration is to:
- Increase zone current draw
- Allow the panel to distinguish between an open, a short, and a normal alarm (Correct answer)
- Replace Class A return wiring
- Reduce wire resistance
Correct answer: Allow the panel to distinguish between an open, a short, and a normal alarm
DEOL uses two resistors of different values so the panel can identify three distinct states: normal, alarm (contact change), open, and short.
Question 6: A technician is pulling wire through an existing metallic conduit. Which wiring consideration is MOST important?
- Ensuring the conduit is PVC-coated
- Verifying fill capacity (conduit fill percentage) is not exceeded (Correct answer)
- Using only solid conductors
- Grounding the conduit to the detector housing
Correct answer: Verifying fill capacity (conduit fill percentage) is not exceeded
NEC Article 760 and conduit fill tables limit how many conductors can share a conduit to prevent heat buildup and installation damage.
Question 7: Stranded wire is preferred over solid wire for alarm installations primarily because it:
- Has lower resistance per foot
- Is easier to route through conduit and more flexible in terminal connections (Correct answer)
- Carries higher voltage ratings
- Has a thicker insulation jacket
Correct answer: Is easier to route through conduit and more flexible in terminal connections
Stranded wire's flexibility reduces insulation cracking during installation and makes reliable terminations easier at device terminals.
CAT Alarm Technician Wiring & Circuits 3
A normally closed (NC) contact connected across a zone loop WITHOUT an end-of-line resistor would cause the panel to: