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difference between smoke detector and smoke alarm
September 10, 2018
difference between smoke detector and smoke alarm from September 1, 2018 article
    This is a good brain teaser for the industry. Thank you.
    I think you are asking the question, So I’ll attempt to provide a detailed answer and some of my thoughts on the proposed language change:
    Smoke alarms are as you’ve described them, but they are likely to be powered (in addition to a battery, for backup) from the buildings electrical circuit wiring inside a home or business. They are similar to a smoke detector (in that they detect smoke) but, also emit the alarm sound upon detection of smoke. Hence the name “Smoke Alarm”. Smoke alarms also come in a few different “flavors” photoelectric technology, ionization technology and combinations of those technologies along with the addition of detecting carbon monoxide. “Combination Smoke Alarms” are also usually powered from the buildings electrical circuitry and backed-up with a battery and include an integral alarm sounder. I suspect that this code language is being proposed to be changed because of the electrical circuitry wiring requirement. Many low voltage licensees (for fire and security systems) do not include the qualifications or continuing education requirements for installing 110vac branch circuitry to other than the security or fire alarm system. A qualified licensed electrician should do this work, typically, not an alarm systems installer.
    Smoke detectors are also as you’ve described them and, in wired versions, are connected to a low-voltage system circuit for their power with battery backup being provided in the security or fire alarm system control panel for system-wide battery backup. Most system-connected smoke detectors do not include an integral alarm sounder instead using sounders also connected to low-voltage system circuitry. These detectors are also available in a wide variety of “flavors” and combinations including photoelectric, ionization, carbon monoxide and variations and combinations of those detection technologies.
    By the way, Buehrer Alarm Systems Consulting offers Vermont state approved fire alarm TQP certification and license renewal continuing education classes. We have upcoming classes in November and December. If interested, contact me for more information.
Matt Buehrer
NICET #94701 Fire Alarm Systems Level III
Buehrer Alarm Systems Consulting, LLC.
Burlington, VT 
cell: 802.578.2733



Smoke alarms have a built-in sounder, hence smoke “alarm”.   They are either stand-alone battery powered where they are installed in existing homes. The smoke alarm sensing smoke sounds.  They all have a battery, but the interconnected ones are also powered by the buildings AC power.  They also may be the multiple-station type where they are interconnected by a third AC wire.  This wire causes them all to sound when one of them detects smoke.   These are used for new installations in new homes.    Alarm companies are not usually licensed for 110 VAC work.   Smoke alarms may optionally be connected to an alarm panel for monitoring or to provide other outputs such as bed shakers.  Smoke alarms are usually the ionization type.

Smoke detectors are always connected to a control panel.  They may also have an optional sounder, but they are always powered by the panel and have backup power.   Smoke detectors can have much more detection features and intelligent operation than its smoke alarm cousins either individually or with the help of the control panel.  Smoke detectors are usually the photoelectric type.

Greg Kessinger SET, CFPS, IMSA, CDT, ICC


 The simple answer to your brain teaser question is this;
 Smoke detectors are connected to a SYSTEM that produces sound or light when the device is actuated.
 Smoke ALARMS make noise when actuated.
 I don't know what's in your house when you say you have fire alarm. Fire alarm is a signal and not a system. You probably have a fire alarm system and it might be connected to burglary devices as well. That is the short answer to your question and I believe you have a Layman's understanding of the differences based on the narrative.
 A more comprehensive answer can be provided but the simple fact is smoke detectors do not make noise and smoke alarms do. I will prepare something more extensive addressing the differences.
Jim Mundy
AFAA Member Emeritus

    I have always been timid to get into this stew, but here goes!  
What is the difference between a SMOKE ALARM and a SMOKE DETECTOR?  It is confusing because they are the same but different.  A Smoke Alarm actually contains a Smoke Detector.  Smoke Alarms are a detector, power supply, control panel, and notification all in a single device.  Approved Smoke Alarms and Smoke Detectors are manufactured under ANSI/UL Standards.  Smoke Alarms are listed and manufactured under ANSI/UL Standard 217.  Smoke Detectors are listed and manufactured under ANSI/UL Standard 268.  Smoke Alarms are intended for residential occupancy life-safety.  
    Residential Occupancy, not just homes.
    Smoke Detectors can be installed in life safety, property protection, and other applications.  Below is a link to the Underwriters Laboratories website with more information and links:
    Buy a Smoke Alarm and a Smoke Detector and read the Manufacturers Installation Instructions for more clarification of use and application. Differences will be very apparent in these two documents.  I am sure that someone will find some fault with my attempt at clarification but it is well intended!
    Please respond in a civil manner.
Hal Lewis
Alarms Unlimited
San Diego, CA
    A smoke detector is connected and powered by a fire alarm system where the audible warning is thru the system’s audible devices. A smoke alarm is self-contained in that it has its own power supply and audible component.  
Robert Baxter, P.E., President/CEO
    One of the basic determining differences is that the Smoke Detector is connected to a control panel. The control panel sounds local alarms and supervises the devices.  A smoke detector is a self contained device that emits an alarm and is self supervised (That annoying chip in the middle of the night that says the battery is dying).  Smoke Detectors may be interconnected as is commonly done in residential homes that does not make them a Smoke Detector System. Even DIY devices that do communicate to a central station such as NEST are still considered Smoke Alarms.  A Fire Alarm consisting of of Smoke detectors can be a local system with no communication for monitoring and is still considered a Smoke Detector system. 
Mark Fischer
    Thanks for providing this informational forum.
    Smoke Alarms vs Smoke Detectors should be no brain teaser for licensed professionals in our industry.  It might sound like semantics  but the difference is significant.  So how can you tell the difference?  It is about the Listing.  To be precise, Single and Multiple Station Smoke Alarms are manufactured to comply with UL 217, Standard for Single and Multiple Station Smoke Alarms.  Smoke Detectors are manufactured to comply with UL 268, Standard for Smoke Detectors for Fire Alarm Systems.  Without checking the listing, it might be hard to tell the difference.  You will want to check the detector, the box it came in, instructions from the manufacturer or the product spec sheet.  One or more of these will confirm what you have.  The detector should also be marked with the date of manufacture.
    The next big question is: What is the significance?  For starters, NFPA 72, 2013 edition Chapter 14.4.7 indicates that Smoke Alarms installed in one and two family dwellings shall not remain in service longer than 10 years from the date of manufacture.  So how about the wireless devices that are so common in residential settings that connect to our control panels.  Some who read this post are going to be surprised to learn that some manufacturers that we use manufacture wireless smoke sensors that are listed to UL 217 while other manufacturers devices are listed to UL 268.  I wonder what the liability would be for an alarm dealer who installs Smoke Alarms that do not detect or annunciate a fire and then it is determined that the devices should have been replaced 2 years before the fire?  Would it be any different for the dealer who notifies the homeowner and that homeowner chooses not to have them replaced?
    Best Regards,
Bob Shoremount
    Here is my best shot at this (at 0'dark thirty on a Saturday morning):
Smoke Alarms:  
    These are typically for residential applications such as - Single-Family Dwellings (this includes duplexes, town homes, apartments, condos, etc...)  It can also include the "dwelling units" for hotels/motels, nursing homes, and other sleeping room applications as allowed by Code.  These devices typically have two types of primary power source:
120VAC w/integral battery back-up
Battery (often a 10-year one)
    Code requires that in dwelling unit, a smoke alarm will be on each level of the unit and in each bedroom.  The alarms will be interconnected, so that when one goes in to alarm, they all go in to alarm, i.e. the integral sounders turn on.
    Interconnection is typically accomplished via wiring, but there are smoke alarms available that interconnect through wireless means.
    Note that CO alarms apply much as the same above.
    Depending on the adopted Code, and how strictly it is enforced, there can be requirements for the smoke alarms to be "interconnected" with the fire alarm system, so that strobes can be activated in the dwelling unit(s).
Smoke Detectors:
    These devices are essentially powered from and monitored by a system panel of some type.  The panels can be basic residential security panels, Listed "combo" commercial security/fire panels, or "fire alarm control panels" that are listed for the application.  Smoke detectors can be classified as:
Conventional - basically is on a "zone" (initiating device circuit [IDC]), and can be 2-wire or 4-wire
2-wire: power and monitoring over the same power of wires
4-wire: separate pairs of conductors for power and monitoring
Addressable - each detector can be identified by location and/or its "address".  Is wired on an SLC, and typically receives its power and communications over a single pair of wires.
    Where the line can blur, is that there are now wireless smoke detectors available for commercially Listed fire alarm panels.  These use a battery for primary power.  The lines can be a bit blurred when smoke detectors are used in dwelling units such as hotel/motel guest rooms, nursing homes, memory care, etc...
    Hope this provides some clarification.
Dave Miller, SET, Principal
MCG Design Services
    Thanks to all the experts who took the time to share their knowledge

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