Filter
Top Products
1
Foreword
Studies have shown that in the United States the use of early warning fire and smoke detection systems has resulted in a significant reduction overall
in fire deaths. The sooner a fire is detected, the better the chances are for survival.
A potential problem with smoke detectors is unwanted alarms that often result in people being desensitized to the alarm system or in severe cases dis-
connecting the system. This is an industry-wide problem that in most cases is caused by improper application, installation and maintenance of smoke
detectors. It is hoped that the information in this guide will be used by those involved with the application, installation and maintenance of fire alarm
systems to minimize these problems.
APPLICATIONS GUIDE
System
Smoke Detectors
Contents
Foreword. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Section 1 – Standards that Apply. . . . . . . . . . . . . . . . . . . . . . . . . 2
NFPA Codes and Standards . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Building and Fire Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Testing Laboratories. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Industry Publications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Manufacturer’s Publications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Section 2 – How Smoke Detectors Work . . . . . . . . . . . . . . . . . . 3
Ionization Smoke Detector Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
Photoelectric Smoke Detector Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Smoke Detector Design Consideration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Considerations in Selecting Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Smoke Detectors Have Limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Section 3 – Typical System Layout. . . . . . . . . . . . . . . . . . . . . . . . 5
Electrical Supervision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Class B Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
Class A Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Wireless Circuits . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
General Zoning Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Fire Safety Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Smoke Detector Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Wiring Installation Guidelines. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Typical Wiring Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Wireless Systems. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Installation Do’s and Don’ts. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Wiring and System Checkout . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Section 4 – Proper Detector Applications,
Placement and Spacing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Where To Place Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Where Not To Place Detectors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Special Application Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Standards for Smoke Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Detector Spacing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
General Spacing Guidelines . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Special Spacing Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
Detectors in Air Handling and Air Conditioning Systems. . . . . . . . . . . . . . . . . 12
Detectors in Above-Ceiling Plenum Areas Including Plenums
Utilized as Part of the HVAC System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Section 5 – Testing, Maintenance and
Service of Detectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Typical Inspection, Test and Maintenance Practices . . . . . . . . . . . . . . . . . . . 13
Section 6 – Troubleshooting Techniques. . . . . . . . . . . . . . . . . . 14
What to Do About Unwanted Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Reasons for Unwanted Alarms. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Maintain an Alarm Log. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Effects of Location or Environment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14
Inspect Detector for Dirt and Review Maintenance. . . . . . . . . . . . . . . . . . . . . 14
Effects of other Systems on Alarm System Wiring. . . . . . . . . . . . . . . . . . . . . . 15
Miscellaneous Causes of Unwanted Alarms . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Responsibilities of Detector Owners and Installers . . . . . . . . . . . . . . . . . . . . 15
Where to Get Help if the Source of Unwanted Alarms Can’t be Found . . . . . 16
Appendix 1 – Glossary of Terms . . . . . . . . . . . . . . . . . . . . . . . . . 17
Appendix 2 – Alarm Log. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19