Douglas Krantz - Technical Writer - Describing How It Works
Get the book Make It Work - Conventional Fire Alarms

Are All Smoke Detectors Polarity Sensitive?

I have a question about something


Mr. Krantz

I have a question... Is it important for smoke detectors to be polarity correct? Are all smoke detectors polarity sensitive?

Thank you, C

Many smoke detectors are polarity sensitive; if the wires aren't landed so the positive wire is on the "+" terminal and the negative wire is on the "-" terminal, the smoke detector won't work. Some smoke detectors are not polarity sensitive; if the positive and negative wires aren't landed correctly, the smoke detector will still operate.

Of course, if a wire is connected to a third terminal on the detector for an annunciator or relay connection, or if the smoke detector is used directly on a Signaling Line Circuit (SLC), the smoke detector is still polarity sensitive.

Long term, if the service technicians have mixed and matched different detectors in the system, some of the detectors wired correctly and some wired reverse, future service on the system can be a nightmare.

Just as a matter of principle, I read the installation instructions that come with the detector, and I always connect the smoke detector as if all smoke detectors are polarity sensitive. That way I don't have to remember which make and model is polarity sensitive.

Douglas Krantz
Based on his electronics training, and his understanding of Life Safety, Douglas Krantz has compiled his knowledge of Conventional Fire Alarm Systems into the book Make It Work - Conventional Fire Alarms. The book covers the basics of the Conventional Fire Alarm System, and shows how Life Safety and internal supervision affects the fire alarm system.

Douglas Krantz -- Fire Alarm Engineering Technician, Electronic Designer, Electronic Technician, Writer

Share This With Friends:

Post this by your fire alarm panel -- It shows the in-house fire alarm system and how it calls the fire department.

Go to the Fire Alarm Description Map Page of Douglas Krantzs Technicians Corner
Go to the Residential Life Safety Map Page of Douglas Krantzs Technicians Corner
Go to the Residential Life Safety Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Alarm Description Map Page of Douglas Krantzs Technicians Corner
Go to the General Electrical Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Alarm Maintaining Map Page of Douglas Krantzs Technicians Corner
Go to the Fire Suppression Map Page of Douglas Krantzs Technicians Corner
Go to the Guest Writer's Guidelines of Douglas Krantzs Technicians Corner
See Trivia on Douglas Krantzs Technicians Corner
This website uses cookies. See Privacy for details.
Get the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Conventional Fire AlarmsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground FaultsGet the book Make It Work - Hunting Ground Faults
Reader's Favorite Articles

What is a Stair Pressurization Fan (SPF)?

Which Way Does Electricity Flow?

What's the Difference Between Class A and Class B?

What Makes the End of Line Resistor So Important?

What is a Flyback Diode?

What is a Fire Alarm System?

What is an RTU (Roof Top Unit)?

What Causes an Open NAC?

Learn about fire alarms, one article at a time -

Keep up on the latest article!




No Charge - Unsubscribe Anytime