As a fire alarm installer or technician, you’re seeking answers to how an Initiating Device Circuit, or IDC, works.
You know it’s an input circuit, but the answers in the equipment maintenance manuals only show how to connect the wires, they really don’t answer the question about how the IDC circuit gets the job done.
Answering questions from installers and technicians, the book “Make It Work – Conventional Initiating Device Circuits” provides insights to many of your questions about how an IDC works.
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Frequently Asked Questions
Supervision and the EOL Resistor
- 1 - Why Does the Fire Alarm Panel Supervise the Wires?
Signal and Power Flow
- 2 - What is a Fire Alarm Signal?
- 3 - What is the Difference Between Electricity Flow and Signal or Power Flow?
- 4 - How Are Fire Alarm Loops Supervised?
- 5 - Why is Supervised Wiring So Important?
- 6 - What is the End of Line Resistor For?
- 7 - What Makes the EOL Resistor so Important?
- 8 - The End of Line Resistor Pulls the Voltage Down?
- 9 - Why Use Pigtails or a UL Listed End-of-Line Resistor?
- 10 - Why Isn't an End of Line Resistor Used the Same Way as a Terminating Resistor?
- 11 - NFPA's Classes of Fire Alarm Paths
- 12 - How to Classify a Signal Pathway
- 13 - What is Conventional Class B Wiring?
- 14 - How Does Conventional Class A Fire Alarm Wiring Work?
- 15 - Can More Than One Class A Circuit be in a Conduit?
- 16 – What is the Quadruple Use of the Initiating Device Circuit (IDC)?
- 17 - How Does Resistance Affect the Initiating Device Circuit (IDC)?
- 18 - Why Install Service Loops on Ceiling Smoke Detectors?
- 19 - Why is There an EOL Resistor on a Pressure Switch?
- 20 - How Do You Troubleshoot Using Supervision Voltage?
- 21 - Why Would a Smoke Detector be Wired Incorrectly?
- 22 - Is the Sense of Time Important in Troubleshooting?
- 23 - What is a Four-Wire Smoke Detector?
- 24 - What is Smoke Power on a Fire Alarm Panel?
- 25 - How do I Connect a Tamper Switch?
- 26 - How do I Wire a 10-Wire Tamper Switch?
- 27 - Why Does Closing Some Sprinkler Valves Show Trouble?
- 28 - What Does Listed Mean?
- 29 - Is Compatibility an Issue with Smoke Detectors?
- 30 - Can I Use a New Panel with Old Detectors?
- 31 - Is this New Control Panel Compatible with the Old System?
- 32 - Can I use Conventional Detectors on Addressable Systems?