Fire Alarm Sounders and Strobes — What They Do and Where to Place Them

When a fire alarm activates, it’s not just about detecting danger — it’s about alerting people quickly and clearly. That’s where sounders and strobes come in. These devices are the audible and visual messengers of your fire alarm system, and their correct placement can make the difference between confusion and safe evacuation.

In this guide, we’ll explain what sounders and strobes do, how they work together, and where they should be installed to meet global safety standards and accessibility needs.

What Are Fire Alarm Sounders?

Sounders are audible notification devices — sirens, bells, or horns — that emit a loud tone when the fire alarm system is triggered. Their purpose is simple: get everyone’s attention and prompt immediate evacuation.

Key features:

  • Loud, distinct tones (often 85–100 dB at 3 meters)
  • May include voice messages in larger systems
  • Can be standalone or combined with strobes (horn-strobes)

Best used in:

  • Corridors and stairwells
  • Offices and classrooms
  • Warehouses and industrial spaces
  • Anywhere people need to hear the alarm clearly

What Are Fire Alarm Strobes?

Strobes are visual notification devices — flashing lights that alert occupants, especially those who are deaf or hard of hearing. In many countries, including the U.S., strobes are required in public and common areas under the Americans with Disabilities Act (ADA) and NFPA 72 standards.

Key features:

  • Bright white or red flashes
  • Rated in candela (brightness) — common values are 15, 75, or 110 cd
  • Often combined with sounders in horn-strobe units
  • Must be visible from all occupied areas

Best used in:

  • Restrooms
  • Meeting rooms and classrooms
  • Lobbies and hallways
  • Sleeping areas in hotels or care facilities

Placement Guidelines

Correct placement ensures that everyone — regardless of hearing ability or location — receives the alert.

Sounders:

  • Mount at ear level (typically 2–2.5 meters above floor)
  • Space evenly to avoid dead zones
  • Avoid placing near noisy equipment that could mask the sound

Strobes:

  • Mount between 80–96 inches (2–2.4 meters) above floor level
  • Ensure visibility from all angles — avoid obstructions like furniture or partitions
  • Use ceiling-mounted strobes in areas with cubicles or high visual barriers
  • Follow candela spacing guidelines (e.g., 75 cd covers a 50 ft x 50 ft area)

Combined horn-strobe units:

  • Ideal for corridors, lobbies, and open-plan offices
  • Reduce installation complexity by combining audible and visual alerts

Learn How to Operate Fire Alarm Systems with Confidence

If you're responsible for a fire alarm system but unsure how to interpret panel messages, reset alarms, or run weekly tests, our How to Operate a Fire Alarm module is designed for non-technical users. It’s perfect for building managers, office staff, and anyone who needs hands-on confidence.

Want to Understand Fire Alarms from the Ground Up?

Our Fire Alarms for Beginners course is the ideal starting point for anyone looking to learn how fire alarm systems work, how to test them, and how to troubleshoot faults — no prior experience required.

Final Thoughts

Sounders and strobes are more than just accessories — they’re essential tools for life safety. By placing them correctly and understanding how they function, you’ll ensure your fire alarm system communicates clearly and inclusively during emergencies.