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Will a Signaling Device Work if It is Wired Backward?

By Douglas Krantz | Descriptions

Will a Signaling Device Work if It is Wired Backward?


Will a Signaling Device Work if It is Wired Backward?


Greetings Douglas,

What would be the result if the correct polarity was not observed during the installation of a Signaling Device in a fire alarm system?

I am in the process of preparing for the industrial electrician exam.

Thank You, xx

Short Answer

Short Answer

The short answer for the test is that the signaling device would fail to operate.

Long Answer

A "Signaling Device" in this context is engineering-speak for a fire alarm device that is used to "Signal" the occupants of the building that a fire has been detected. The most common devices would be horns and strobes. Included in the signaling device category would be chimes, bells, and speakers.

Another way of describing these devices is "Notification Appliances". Notification appliances are connected to a Notification Appliance Circuit (NAC).

All of the conventional devices except the speakers have a diode inside them to block (prevent) electrical current from passing through them in the wrong direction. Conventional speakers have a capacitor inside them to prevent DC electricity from ever passing through them, while the capacitor allows audio to pass through.

Addressable notification appliances are always polarity sensitive. They will not work at all if the polarity is not observed.



Douglas Krantz

facpdoug@gmail.com
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