Installation Techniques Flashcards

During a new commercial installation, the alarm technician discovers the specified wire run is 600 feet from the panel to a smoke detector. What concern must be addressed?

Answer: Voltage drop over the long run may prevent proper device operation

Long wire runs create voltage drop due to wire resistance; the technician must use a heavier gauge wire or add a booster to ensure adequate voltage at the end device.

What is the function of the tamper switch built into an alarm device enclosure?

Answer: It triggers a supervisory or trouble condition if the enclosure is opened or removed from the wall

The tamper switch detects unauthorized opening or removal of the device, sending a tamper signal to the panel to alert monitoring personnel.

When installing a dual-tech (PIR + microwave) motion detector, what is the main advantage over a standard single-technology PIR?

Answer: Both technologies must trip simultaneously to generate an alarm, drastically reducing false alarms

Dual-tech detectors use an AND logic — both the PIR and microwave channels must detect motion at the same time — which significantly reduces false alarm rates.

A technician installs a siren strobe on the exterior of a residence and connects it with a wire run through the brick wall. What is the proper way to seal the wall penetration?

Answer: Use an exterior-grade silicone sealant or weatherproof putty around the conduit or wire

Exterior wall penetrations must be sealed with weatherproof sealant to prevent moisture, insects, and drafts from entering the building or damaging the wiring.

When a technician programs a zone as '24-hour' on an alarm panel, what behavior does this define?

Answer: The zone is active at all times regardless of whether the system is armed or disarmed

A 24-hour zone is always active — it will trigger an alarm any time it is faulted, even when the system is disarmed, making it ideal for smoke, CO, and panic devices.

What is the correct method for splicing two alarm wires inside a wall cavity where no junction box is accessible?

Answer: Use UL-listed wire connectors (wire nuts) and place them in a listed junction box or access point

NEC requires all wire splices to be made in listed junction boxes that remain accessible for inspection and future service.

When installing a carbon monoxide (CO) detector as part of a residential alarm system, at what height should it ideally be mounted?

Answer: At the same height as light switches, approximately 48 inches from the floor

CO has nearly the same density as air and mixes uniformly, but manufacturer and NFPA 720 guidance recommends mounting CO detectors at approximately 48 inches (outlet/switch height) or per the manufacturer's instructions.