CAT Alarm Technician Wiring & Circuits 2

Question 1

A supervised zone loop measures 0 ohms resistance. What condition does this indicate?

Accepted Answer

Short circuit fault

Answer

Zero ohms across a supervised zone indicates a short circuit, which bypasses the end-of-line resistor and causes a fault condition.

Question 2

Which wire type is MOST appropriate for runs near high-voltage AC power lines to prevent interference?

Accepted Answer

Shielded twisted pair

Answer

Shielded twisted pair rejects electromagnetic interference (EMI) induced by nearby AC power conductors.

Question 3

In a Class A (Style D) initiating device circuit, what distinguishes it from a Class B circuit?

Accepted Answer

It requires a return path so the panel can detect a wire break beyond the break point

Answer

Class A wiring returns from the last device back to the panel, allowing the panel to continue supervising devices beyond an open-circuit fault.

Question 4

A technician measures 13.8 VDC at the panel but only 11.2 VDC at the last detector on a long run. What is the most likely cause?

Accepted Answer

Excessive voltage drop due to wire resistance

Answer

Voltage drop across the wire resistance (V = I × R) reduces available voltage at the end of a long loop.

Question 5

When wiring a 4-wire smoke detector, the ALARM output wires connect to:

Accepted Answer

The initiating device circuit (IDC) zone input

Answer

The two power wires supply the detector; the two alarm wires connect to the panel's IDC zone to report an alarm.

(CAT) Certified Alarm Technician Level I Practice Test