Does it matter if the smoke detector's four-wire (power and signal wires) touched?

Ask your question such as how to install home security systems, where to place the motion sensor, what type of smoke detector to choose for my case etc. Professional security system technician will answer the questions.
Post Reply
Jim
Posts: 51
Joined: Sat Oct 31, 2020 1:01 pm

Does it matter if the smoke detector's four-wire (power and signal wires) touched?

Post by Jim »

Question:
The four wires of GND, NO NC 12V touched each other when they were disassembled, and the display light did not turn on after they were connected. What is wrong?
Answer:
1. This should be a security linkage smoke detector with alarm output.
2. The 12V and GND marked by the detector are the power lines of the detector as well as the signal lines, and the working voltage is DC12V (the working power range is usually 9~28V).NO and NC are the output contacts of the detector relay and it actives when the detector alarms. Generally it can be set to normally open or normally closed.
3. If the output contact of relay is used, it can be used as the automatic switch of other circuits with different voltages, generally DC24V. If the contact relay output circuit is not disconnected and the 4 wires touches, it is possible to damage the detector circuit (if the power line is not untied), even if the power line is untied, it is possible to break the electronic component of the detector.
4. If the output contact of the relay is not in use, the detector will not be affected if the power line is only touched and not short-circuited.
5. The indicator light of the detector flashes under normal conditions. After the alarm of the detector, the indicator light is always on; after the alarm is lifted, the indicator light returns to normal.
6. Fault detection: If the output contact of the relay is connected to the DC24V circuit, the power circuit is most likely to fail, and the detector is relatively less likely to be damaged.Therefore, first check whether other detectors in the detector circuit are normal. If other detector indicator lights are not on, the detector power circuit may fail. Check whether the short-circuit isolator or the host's insurance is normal and whether the power cord is broken.If the power circuit is normal, check for damage to other detectors;If the other detector indicator light is normal, change the normal detector to access the disassembly detector position to determine whether the disassembled detector is damaged.
7. To remove the detector, NO and NC loop should be removed firstly, and then the power line should be removed.

vedard
Posts: 532
Joined: Wed Dec 05, 2018 12:27 am

Should I turn off the alarm panel when I move the smoke detector

Post by vedard »

Question:
There is an addressable fire alarm smoke detector which should be moved to another place. So, my question is: Should I need to turn off the fire alarm panel when I move the smoke detector?
Answer:
In the fire alarm system, smoke detector and heat detector adopt multi-point linkage. That is, all detectors are connected in parallel to the circuit. If there is only one smoke detector alarm, the host will not trigger the linkage even if it receives the signal. If there is only one smoke detector alarm, the host will not trigger the linkage even if it receives the signal, start the sound and light alarm and broadcast system, land the fire shutter door, crash landing elevator, etc.
Therefore, when move the smoke detector (or heat detector), the accurate position of the new smoke detector should be determined firstly, and then thread the wire through the pipe to connect with the original detector. According to the principle and careful wire it, avoid short circuit to trigger false alarm.
You can switch the fire alarm panel automatic linkage to manual linkage before the moving of the detector. So, not need to turn off the alarm panel.
move smoke detector.jpg
move smoke detector.jpg (84.33 KiB) Viewed 318 times
Shop Focus brand wireless alarm, HB solar power alarm, HST fire alarm at https://www.vedardalarm.com

Jim
Posts: 51
Joined: Sat Oct 31, 2020 1:01 pm

How to test smoke detector with multimeter?

Post by Jim »

Smoke detectors prevent fires by detecting the concentration of smoke.The commonly used smoke detectors are ionic type and photoelectric type. Under normal circumstances, the smoke detector will check itself every once in a while, and the indicator light will flash with an interval of about 4-5 seconds. The newly installed smoke detector may have duplicate code, missing code, etc. Failure of the smoke detector in use may be due to poor contact between the base and the smoke detector, or caused by dust or water fog. The smoke detector can be disassembled and tested again after cleaning the dust. The normal flashing light indicates that the detector is working normally. If it still does not work properly, a backup smoke detector or adjacent smoke detector can be used to replace and test.
Multimeter can be used for further inspection. The main device of smoke detector is gas sensor, and the commonly used gas sensor is MQK-2A. We can use a multimeter to measure the resistance at both ends of the pin and the resistance to earth. Normally its resistance is tens of thousands of ohms and its resistance to earth is 2M ohms. And then you can measure its voltage, if the supply voltage is 6V, it should be 2.5-6V. If both the resistance and voltage are correct, there is nothing wrong with the smoke detector itself.
Attachments
smoke detectors.jpg
smoke detectors.jpg (45.45 KiB) Viewed 292 times
smoke alarm diagram.jpg
smoke alarm diagram.jpg (65.99 KiB) Viewed 292 times
smoke alarm circuit.jpg
smoke alarm circuit.jpg (38.24 KiB) Viewed 292 times

vedard
Posts: 532
Joined: Wed Dec 05, 2018 12:27 am

Fire alarm system open pipe requirement

Post by vedard »

Question: Open pipe laying is adopted in the renovation of fire protection alarm system.What are the requirements for the laid pipe?
Answer: The transmission lines of the automatic fire alarm system shall be protected by metal pipes, flexible (metal) electrical conduits, rigid plastic pipes of Class B1 or above, or enclosed groove. Mineral insulated non-flammable cables can be laid directly.
The power supply line and fire linkage control line of the automatic fire alarm system should adopt refractory copper core wire and cable.Transmission lines such as alarm bus, fire emergency broadcast and special fire telephone shall be flame retardant or fire retardant wire and cable.
Attachments
fire alarm system cable laying.JPG
fire alarm system cable laying.JPG (40.08 KiB) Viewed 287 times
Shop Focus brand wireless alarm, HB solar power alarm, HST fire alarm at https://www.vedardalarm.com

Post Reply