Fire Alarm Systems -- What are Class A Loops?
In case a wire breaks, to keep more devices working, Class A uses a second path from the fire alarm panel; a redundant wire loop goes around the broken wire.
Fire Alarm Systems -- What is a Ground Fault?
Ground Faults are one of the simplest problems in a fire alarm system, an yet they're one of the hardest problems to find.
Electronics -- What is a Flyback Diode?
Manufacturers the world over spend good money installing these diodes, they must think they're important. What could be so important about a little diode?
Electicity - - Conventional Flow or Electron Flow?
Electrical Engineers and Electronic Technicians each think electricity flows the opposite direction. Why don't they agree?
Fire Alarm Systems -- What is a Waterflow Switch?
It doesn't turn on the water. It doesn't turn off the water. A waterflow just detects that water is flowing.
Fire Alarm Systems -- Wire Loop Supervision of the Fire Alarm System Helps Insure the System Will Work
Because the fire alarm system is a Life Safety System (people's lives depend on the fire alarm system working in an emergency), using supervision, the panel makes sure the field devices are always connected to the loop
Fire Alarm Systems -- What is an RTU (Roof Top Unit) and How is it Affected by Duct Detectors?
Help! I have an alarm on my fire alarm panel saying something about RTU, but it won't reset. I can't get any heat out of my furnace, either.
Because both a thick and a thin wire are under the same screw plate, when screwed down on the wires the plate cannot press against both wires evenly. One wire is always looser, and the loose wire shows up later as a trouble on the panel.
Fire Alarm Systems -- Wiring a Door Holder
The door holder looks innocent, and shouldn't be able to damage anything, so how does a door holder damage the Fire Alarm Control Relay that shuts off the current?
Fire Alarm Systems -- What Should I Do When the Fire Alarm Sounds?
When the Alarm Sounds -- I would never suggest turning off the fire alarms, or in any way delay calling the fire department -- So says Brad Sveum, fire marshal ...
Addressable Supervision of the Signaling Line Circuit (SLC)
Supervision of Addressable Fire Alarm Systems is done with Polling of the Devices. How does Polling of the Devices confirm that the wiring is intact?
Eletronics -- Ohms Law - E=IR Isn't Just a Word
If it isn't just a word, and it isn't really something to be memorized in order to pass a test, what do the letters in Ohm's Law really mean?
Fire Alarm System -- Class B Wiring
How does the Fire Alarm Control Panel detect a wiring problem somewhere else in the building? System Wiring Integrity - That's what Class B Wiring is all about
Fire Alarm Systems -- Troubleshoot Using Supervision Voltage
You've got the supervision voltage right at the terminals on the panel, use it to troubleshoot what the panel is seeing.
Notification Appliance Circuit Voltage
Horns and Strobes get turned on when proper polarity voltage is applied. Normally, it's supervision voltage that's applied. The difference between the two can cause problems unless one pays attention.