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Fire Alarm Descriptions
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Firefighter Don't Reset the False Alarm -- When the alarm sounds and the firefighter arrives, even for a false alarm, the firefighter is on site for property protection and life safety. So when leaving, from the point of view of the firefighter, the ... Read More

Is the Fire Alarm Control Panel Necessary? -- Having detected a fire, a fire alarm system sounds the alarm. Other than the building wires that carry the signal from the fire detector to the fire horn, everything else in a fire alarm system ... Read More

What is a Fire Alarm Zone? -- Building zones aren't determined by where the wires are run for the fire alarm system, building zones are determined by the building's fire-control -- fire-fighting divisions and by the building's smoke-control divisions... Read More

How Does Multiplexing of the Signaling Line Circuit Work? -- Depending on what one needs to understand about a circuit, the circuit can be thought about in different ways. Take for instance a Signaling Line Circuit (SLC). A Signaling Line Circuit is a circuit that starts from the...Read More

What Makes the End of Line Resistor So Important? -- To allow the panel's internal ohmmeter to check the continuity of the wires (supervise the wires), the end-of-line resistor is at the end of the loop: the last device. Read More

What Is Fire Alarm Trouble Power? -- In the "Old School" type of fire alarm system, before the smoke detector was invented, even though the fire alarm systems used AC, all voltages were in a steady state: either on or off. Until someone ... Read More

Just What Is a Signaling Line Circuit (SLC)? -- The SLC (Signaling Line Circuit) is another way of saying Data and Power Circuit. Along with added power to run the sub-computers and their input and output circuits, it's a computer data-buss ... Read More

If It's There -- It Has To Work -- Whether its smoke detectors on the ceiling or the firefighter's telephone system, people think that if it's there, it's real and it works. Sometimes, people even stake their lives on that device or system ... Read More

What is a 4 Wire Smoke Detector? -- Even though it uses an internal protection resistor and internal alarm relay contacts, a 4 wire smoke detector is basically a 2 wire smoke detector; it detects smoke and sends an alarm ... Read More

Why Can't You Reset a Trouble on a Fire Alarm Panel? -- Often times, when going on a service call as a troubleshooter, the building manager or maintenance person says... Read More

Why Have Wire that Lasts 2 Hours in a Fire? -- The fire alarm system is used to tell people when it's their turn to evacuate a burning building. Evacuation sometimes takes time... Read More

What is a Fire Alarm System? -- Long ago, as earliest method of spreading the word of fire danger, people shouted "Fire!" Depending on the circumstances, people would run... Read More

What are those Lights and Buttons on the Fire Alarm System For? -- You're now in charge of the building, be it an apartment building, office building, business complex, or industrial complex and now you have to deal... Read More

What Should One Look For in a Fire Alarm Panel? -- The question has been asked, "Which is the best fire alarm panel?" A fire alarm system isn't: installed for the manufacturer or... Read More

What is Total, Staged, and Defend-in-Place Evacuation? -- For their own safety, when the fire alarm sounds, people want to get out of a burning building. Sometimes, though, there's a hitch ... Read More

What Makes a False Alarm so Dangerous? -- Each false fire alarm increases the severity of a real fire. The increased severity from false alarms comes from the greater chance of loss of life or a greater chance of injury. This is a progression - with no false... Read More

Why Have a Written Fire Evacuation Plan? -- One time, I had a fire inspector tell me that he requires a written evacuation plan for all buildings. The reason... Read More

How good are those Call 911 signs above pull stations? -- The Fire Marshal didn't have the authority to require the owner to upgrade the fire alarm system to use off-site monitoring. Because... Read More

I Can't Fix Fire Alarm Systems that are Reset -- Help! I service fire alarm systems. When I'm on call, I have to respond on a 24/7 basis to fix fire alarm systems . This includes those systems that... Read More

Can One Company Really Keep the Other Company In Line? -- I'd like to tell you a story about dishonesty. Not the kind where a vendor knows he is doing wrong, and... Read More

What is Mass Notification? -- When a disaster or emergency strikes, and everyone in the area is to take action now, a Mass Notification... Read More

What is an Area of Refuge? -- You hear the message "Use the Stairs, "you see the sign "In case of fire, don't take the elevator." To get out of the building from the higher floors, when the building is on fire, the stairs ... Read More

How is a Buffer Relay Wired Into a Door Holder Circuit? -- Like a door stop, a door holder keeps a fire door open. When smoke is detected, the door holder releases, allowing the door to shut. The door holder looks simple and innocuous enough... Read More

How Are Fire Alarm Loops Supervised to Make Sure They Continue to 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... Read More

Why Does the Fire Alarm Panel Supervise the Wires? -- Supervision of building wiring isn't really to make sure the wires are good, supervision of building wiring is to make sure all the devices are ... Read More

How Do You Troubleshoot Using Supervision Voltage? -- With Fire Alarm Systems , one method of troubleshooting is measuring supervision voltage . It's the voltage at the panel's IDC input terminals (Initiating Device Circuit for... Read More

How Does the Fire Panel Know Addressable Detectors are OK? -- It's assumed that fire alarm systems have to work all the time because fires happen anytime, but, then again, this is the real world. Problems with... Read More

Class B and Class A Wiring -- The Fire Alarm System is a Life Safety System - so the occupants of a building can escape quickly, the idea... Read More

What's the Difference Between Class A and Class B? -- Fire alarm people are paranoid. They're afraid everything is working against them. They're in fear that that if anything goes wrong... Read More

How Does Class A Fire Alarm Wiring Work?-- Fire alarm systems save lives and protect property. Fire alarm systems also break down because... Read More

How is an End of Line Resistor a Pull-Down Resistor? -- Sometimes when troubleshooting, the technician has to think inside the box. For instance, take... Read More

Why Use Class A to Network Fire Alarm Panels Together? -- In a tall building, should the network connecting the fire alarm panels together be Class B, or Class A? Read More

How Does Resistance Affect the Initiating Device Circuit (IDC)? -- IDC circuits (Initiating Device Circuits) are input circuits to the fire alarm control panel, and...Read More

What is a Booster Power Supply or Signal Power Expander? -- A fire alarm system consists of input devices to detect a fire (automatic detectors and manual pull stations), output devices to notify occupants of... Read More

What Is a Conventional Notification Appliance Circuit or NAC?-- NAC is the acronym for Notification Appliance Circuit. Notification: Tells people of a Fire or other Life... Read More

What is Notification Appliance Circuit (NAC) Supervision? -- In the Notification Appliance Circuit (NAC), conventional fire horns, bells, strobes, chimes, and speakers, all have the... Read More

What will a Shorted Fire Strobe Do? -- Some time ago, at a high rise business and condominium building, I inspected a fire alarm system. On arrival, the fire alarm control panel showed...Read More

Why is the Voltage on the Notification Appliance Circuit (NAC) so Weird? -- Normally, when the Notification Appliance Circuit (NAC) isn't in trouble, the NAC is in one of two states or conditions: Alarm (making noise and... Read More

Why does Fire Alarm Strobe Current Go Up as Voltage Goes Down? -- In a fire alarm system, strobes are notification appliances; the flashing strobes get people's attention. They're constant... Read More

What is a Fire Alarm Klaxon? -- Before there were DC fire horns, and as an alternative to clanging bells, klaxons were used to notify... Read More

Why Can't a 70 Volt Speaker be Used With a Fire Alarm System? -- When the fire alarm system is active and is being used for EVAC or voice, there is no difference between the speaker audio used... Read More

What is an RTU (Roof Top Unit)? -- "Help! I have an alarm on my fire alarm panel saying something about RTU, but it won't reset," so goes the cry... Read More

What is Smoke Power on a Fire Alarm Panel? -- 2 Wire Smoke Detectors are connected to the Zone Inputs of a conventional Fire Alarm Control Panel (FACP) , and so too are 4 Wire... Read More

Conventional Four Wire Air Duct Smoke Detectors -- Conventional Air Duct Smoke Detectors are assemblies that include a smoke detector, support electronics, and an internal power supply. The minimum requirements... Read More

What is Smoke Detector Verification?-- Because smoke comes in so many varieties, smoke detectors have to be sensitive... Read More

Should the Detector be Photo, Ion, or Both? -- In a smoke alarm, the smoke detector senses particles in the air from a fire and then the alarm sounds. Hearing the... Read More

Why do Fire Alarm Pull Stations Break? -- Ever wonder why a manual pull station tends to break when someone attempts to push it back after setting off the alarms ? I, too, have been wondering... Read More

Why Does a Smoke Detector Stop the Elevator? -- Back in the early '70s, the disaster movie "Towering Inferno" depicted a fire in a high rise office building. Trapping partygoers... Read More

What is a Firefighter's Telephone System? -- In a large building, so they can talk to each other while battling fires, firefighters use their two-way radios. But when the radios just don't work, the firefighter's... Read More

What is a Stair Pressurization Fan (SPF)? -- In case of fire in a high rise building, an SPF uses clean outside air to pressurize the air in stairwells. The pressurized air helps people escape... Read More

Is the NFPA Code the Law or a Recommendation? -- In the United States, the National Fire Prevention Association (NFPA) fire codes are strange. They aren't codes; they're... Read More




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