Fire Alarm Industry FAQ

Gabriel Oliveira
Fire Alarm Industry FAQ

Common Questions About Fire Alarms, Smoke Detectors, Codes, Installation, and Maintenance

1. What is the difference between a smoke detector and a fire alarm?

A smoke detector senses smoke and typically includes a local sounder.
A fire alarm system is a network of devices — detectors, pull stations, modules, notification appliances, and a control panel — that monitors a building and triggers building-wide alerts and emergency responses.

Homes usually use individual smoke alarms.
Commercial buildings require full fire alarm systems.

2. What types of smoke detection technologies exist?

The most common types are:

  • Photoelectric: Best for smoldering fires (slow-burning, heavy smoke).

  • Ionization: Best for fast-flaming fires with smaller particles.

  • Dual-sensor: Combines both technologies for broader protection.

  • Aspirating (like VESDA): Highly sensitive and used in high-risk or mission-critical areas such as server rooms, clean rooms, and warehouses.

  • Beam detectors: Used in large open spaces (gymnasiums, atriums, industrial buildings).

3. How often should smoke detectors be replaced?

Most manufacturers and NFPA guidelines recommend replacement every 10 years.
Commercial intelligent detectors may require replacement sooner depending on contamination, environment, or manufacturer specifications.

4. What is the difference between residential and commercial smoke detectors?

  • Residential units (BRK, First Alert, Kidde, etc.) are stand-alone alarms, sometimes interconnected, usually with internal sounders.

  • Commercial detectors (System Sensor, Notifier, Fire-Lite, Edwards, Kidde, Siemens, etc.) are addressable or conventional heads that report back to a fire alarm control panel.

They are not interchangeable.

5. Do commercial fire alarm systems require professional installation?

Yes.
NFPA 72 and local fire codes require that commercial fire alarm systems be installed, tested, and certified by licensed fire alarm contractors or NICET-certified technicians.

6. Can I mix brands on a fire alarm system?

Usually no.
Most fire alarm panels communicate only with devices from the same manufacturer family (Notifier with Notifier, Fire-Lite with Fire-Lite, Kidde with Kidde, etc.).
Mixing brands can lead to communication errors, non-compliance, and failed inspections.

7. What is the difference between addressable and conventional fire alarm systems?

  • Conventional systems: Identify alarm conditions by zone.

  • Addressable systems: Identify the exact device address in alarm or trouble.

Addressable systems improve troubleshooting, reduce false alarms, and provide better diagnostics.

8. Why does my fire alarm keep going into trouble mode?

Common causes include:

  • Loose wires or poor connections

  • Low or missing batteries

  • Dirty or aging smoke detectors

  • Ground faults

  • Device removed from its base

  • Communication errors on the loop

Trouble signals must be investigated immediately, even if the alarm isn't sounding.

9. How often should fire alarm systems be tested?

Per NFPA 72, fire alarm systems should be:

  • Inspected monthly (visual checks)

  • Tested annually (full alarm test)

  • Smoke detectors sensitivity tested every 2 years unless using self-monitoring sensors

Some AHJs (Authorities Having Jurisdiction) may require more.

10. Do I need carbon monoxide detectors as well?

Yes, if your building has:

  • Gas appliances

  • Attached garage

  • Fuel-burning equipment

  • Boiler rooms

  • Locations required by code

Many devices today are Smoke + CO combos (e.g., BRK SC9120LBL, First Alert Precision Detection).

11. Where should smoke detectors be installed in a home?

NFPA recommends:

  • Inside every bedroom

  • Outside every sleeping area

  • On every level of the home

  • In basements

  • In living rooms and hallways

Avoid installing directly next to kitchens or bathrooms to prevent nuisance alarms.

12. What is a duct smoke detector and when is it required?

A duct detector monitors smoke in HVAC ducts.
They are required when smoke movement through air ducts could spread fire rapidly or when shutting down HVAC systems is necessary to prevent smoke circulation.

Brands include System Sensor, Edwards, Kidde, and Siemens.

13. What is a heat detector and where should it be used?

Heat detectors respond to temperature, not smoke.
They are ideal for:

  • Garages

  • Kitchens

  • Attics

  • Mechanical rooms

  • Warehouses

  • Dusty or dirty environments where smoke detectors would false alarm

Heat detectors include fixed temperature, rate-of-rise, and combination types.

14. How long do fire alarm control panels last?

Most panels operate 10–20 years depending on:

  • Environment

  • Firmware availability

  • Code changes

  • Replacement parts availability

Panels older than 20 years often become non-serviceable and require upgrades.

15. Why do fire inspectors require UL-listed devices?

UL (Underwriters Laboratories) listing ensures:

  • The device meets national safety standards

  • Testing has been performed for fire response performance

  • Components are approved for commercial or residential use

Non-UL devices are almost always rejected by inspectors.

16. What is the difference between NFPA 72 and NFPA 70 (NEC)?

  • NFPA 72: The National Fire Alarm & Signaling Code — covers detection, notification, installation, testing, and maintenance.

  • NFPA 70 / NEC: Covers electrical wiring requirements, circuit protections, and installation practices for power-limited fire alarm wiring.

Both apply to commercial fire alarm work.

17. Do all fire alarms need backup batteries?

Yes.
Commercial systems are required to have 24 hours of standby power plus additional time in alarm.
Residential hardwired alarms typically use 9V or sealed 10-year backup batteries.

18. What causes false alarms in smoke detectors?

Most false alarms come from:

  • Cooking aerosols

  • Steam from showers

  • Dust buildup

  • Insects entering the sensing chamber

  • Expired sensors

  • Electrical issues

Regular cleaning and proper placement reduce false alarms dramatically.

19. What is interconnection and why is it important?

Interconnected alarms all sound when one unit goes into alarm.
This is critical in:

  • Multi-level homes

  • Apartments

  • Large layouts

BRK / First Alert hardwired models and wireless-enabled alarms offer full interconnect capability.

20. What brands are most trusted in the fire alarm industry?

Depending on the category:

Residential

  • BRK / First Alert

  • Kidde

  • Nest Protect

Commercial Conventional & Addressable

  • Simplex

  • Fire-Lite

  • Edwards

  • Siemens

  • Kidde

  • Potter

  • Mircom