Editing Smoke detector (section)

==Residential==
Smoke alarm systems used in a home or residential environment are typically smaller and less expensive than commercial units. The system may include one or more individual standalone units, or multiple, interconnected units. They typically generate a loud acoustic warning signal as their only action. Several detectors (whether standalone or interconnected) are normally used in the rooms of a dwelling. There are inexpensive smoke alarms that may be interconnected so that any detector triggers all alarms. They are powered by mains electricity, with disposable or rechargeable battery backup. They may be interconnected by wires, or wirelessly. They are required in new installations in some jurisdictions.<ref>{{cite web |url=https://nest.com/support/article/Why-are-interconnected-smoke-alarms-better-than-standalone-smoke-alarms |title=Why are interconnected smoke alarms better than standalone smoke alarms? |newspaper=Nest Web site |date=17 June 2015 |author=Nest Labs |access-date=7 January 2016 |url-status=live |archive-url=https://web.archive.org/web/20160304110902/https://nest.com/support/article/Why-are-interconnected-smoke-alarms-better-than-standalone-smoke-alarms |archive-date=4 March 2016 }}</ref>

Several smoke detection methods are used and documented in industry specifications published by [[Underwriters Laboratories]].<ref>{{Cite document |publisher=Underwriters Laboratories 217 | title = Single and Multiple Station Smoke Alarms, UL 1971: Signaling Devices for the Hearing Impaired, UL 268: Smoke Detectors for Fire Alarm Signaling Systems }}</ref> Alerting methods include:

* Audible tones
** Varies between 2,900 and 3,500 [[Hertz|Hz]] depending on brand and model name
** 95 [[decibel|dB]] loudness at 3 ft, can vary between brands and models.
* Spoken voice alert
* Visual [[strobe light]]s
** 177 [[candela]] output
* [[Emergency light]] for illumination
* Tactile stimulation (e.g. bed or pillow shaker), although no standards existed as of 2008 for tactile stimulation alarm devices

Some models have a hush or temporary silence feature that allows silencing, typically by pressing a button on the housing, without removing the battery. This is especially useful in locations where false alarms can be relatively common (e.g. near a kitchen), or situations where users might remove the battery permanently to avoid the annoyance of false alarms, preventing the alarm from detecting a fire should one break out.

While current technology is very effective at detecting smoke and fire conditions, the deaf and hard-of-hearing community has raised concerns about the effectiveness of the alerting function in awakening sleeping individuals in certain high-risk groups. People part of groups like the elderly, those with hearing loss, and those who are intoxicated, may have a more difficult time using sound-based detectors.<ref>{{cite web|url=http://www.hearingloss.org/advocacy/pressrelease080207.asp|title=Alarm concern from the Hearing Loss Association of America|website=hearingloss.org|access-date=8 May 2018|archive-url=https://web.archive.org/web/20070927051359/http://www.hearingloss.org/advocacy/pressrelease080207.asp|archive-date=27 September 2007}}</ref> Between 2005 and 2007, research sponsored by the United States [[National Fire Protection Association]] (NFPA) focused on understanding the cause of the higher number of deaths in such high-risk groups. Initial research into the effectiveness of the various alerting methods is sparse. Research findings suggest that a mid-frequency (520 Hz) square wave output is significantly more effective at awakening high-risk individuals. Wireless smoke and carbon monoxide detectors linked to alert mechanisms such as vibrating pillow pads for the hearing impaired, strobes, and remote warning handsets are more effective at waking people with serious hearing loss than other alarms.<ref>{{cite web|url=http://www.hearinglossweb.com/tech/alrt/smoke/low.htm|title=All about Hearing Loss|website=www.hearinglossweb.com|access-date=8 May 2018|archive-url=https://web.archive.org/web/20100618073004/http://www.hearinglossweb.com/tech/alrt/smoke/low.htm|archive-date=18 June 2010}}</ref>

=== Batteries ===
[[File:Smoke detector alarm battery beep.webm|thumb|Audio of a smoke detector with low power]]
Batteries are used either as sole or as backup power for residential smoke detectors. Mains-operated detectors have disposable or rechargeable batteries as a backup. Purely battery-powered detectors typically use either a 9-volt disposable battery that must be replaced every one to two years, or non-replaceable batteries that last about 10 years, meaning the detector must be replaced when the battery runs low.<ref>{{Cite web |title=What is a 10-Year Sealed Battery Smoke Detector? |url=https://www.firstalert.com/us/en/safetycorner/what-is-a-10-year-smoke-alarm/ |access-date=2025-05-18 |website=www.firstalert.com |language=en}}</ref>

When the battery is exhausted, a battery-only smoke detector becomes inactive; most smoke detectors chirp repeatedly if the battery is low in power. It has been found that battery-powered smoke detectors in many houses have dead batteries. It has been estimated{{When|date=January 2016}} that in the UK, over 30% of smoke alarms have dead or removed batteries. In response public information campaigns have been created to remind people to change smoke detector batteries regularly. In Australia, for example, a public information campaign suggests that smoke alarm batteries should be replaced on [[April Fools' Day]] every year.<ref>{{cite web|last=Beacham|first=Janine|title=Don't be a fool: change alarm batteries|url=http://www.margaretrivermail.com.au/news/local/news/general/dont-be-a-fool-shange-alarm-batteries/2119255.aspx|publisher=Augusta Margaret River Mail|access-date=19 April 2011|archive-url=https://web.archive.org/web/20110403140053/http://www.margaretrivermail.com.au/news/local/news/general/dont-be-a-fool-shange-alarm-batteries/2119255.aspx|archive-date=3 April 2011}}</ref> In regions using [[daylight saving time]], campaigns may suggest that people change their batteries when they change their clocks or on a birthday.

Some mains-powered detectors are fitted with a non-rechargeable [[lithium battery]] for backup with a life of typically ten years. After this, it is recommended that the detector be replaced. User-replaceable disposable [[Nine-volt battery#Lithium 9V/PP3|9-volt lithium batteries]], which last at least twice as long as alkaline batteries, are also available for smoke detectors.

The US National Fire Protection Association (NFPA) recommends that homeowners replace smoke detector batteries at least once per year, or sooner if they start chirping (a signal that the battery is low on power output). Batteries should also be replaced when or if they fail a test, which the NFPA recommends to be carried out at least once per month by pressing the "test" button on the alarm.<ref>{{cite web
 |url         = http://www.nfpa.org/itemDetail.asp?categoryID=1647&itemID=39905&URL=Research%20&%20Reports/Fact%20sheets/Smoke%20alarms/Smoke%20alarm%20safety%20tips&cookie_test=1
 |title       = SMOKE ALARM SAFETY TIPS
 |publisher   = National Fire Protection Association
 |work        = Safety Information.
 |access-date  = 2009-05-17
 |url-status     = live
 |archive-url  = https://web.archive.org/web/20090821222032/http://www.nfpa.org/itemDetail.asp?categoryID=1647&itemID=39905&URL=Research%20&%20Reports%2FFact%20sheets%2FSmoke%20alarms%2FSmoke%20alarm%20safety%20tips&cookie_test=1
 |archive-date = 2009-08-21
}}</ref>

=== Reliability ===
A 2004 [[NIST]] report concluded that "Smoke alarms of either the ionization type or the photoelectric type consistently provided time for occupants to escape from most residential fires," and, "Consistent with prior findings, ionization type alarms provided somewhat better response to flaming fires than photoelectric alarms (57 to 62 seconds faster response), and photoelectric alarms provided (often) considerably faster response to smoldering fires than ionization type alarms (47 to 53 minutes faster response)."<ref name="NIST" />

Regular cleaning can prevent false alarms caused by the build-up of dust and insects, particularly on optical-type alarms as they are more susceptible to these factors. A vacuum cleaner can be used to clean domestic smoke detectors to remove detrimental dust. Optical detectors are less susceptible to false alarms in locations such as near a kitchen producing cooking fumes.<ref>{{Cite web|title=Cleaning Smoke and Heat Alarms|url=http://www.sdfirealarms.co.uk/cleaning-smoke-and-heat-alarms|website=SDFireAlarms.co.uk|publisher=Hav Direct|date=2011|access-date=2015-07-31|url-status=live|archive-url=https://web.archive.org/web/20150925103532/http://www.sdfirealarms.co.uk/cleaning-smoke-and-heat-alarms|archive-date=2015-09-25}}</ref>

On the night of May 31, 2001, Bill Hackert and his daughter Christine of [[Rotterdam (town), New York|Rotterdam, New York]], died when their house caught fire and a [[First Alert]] brand ionization smoke detector failed to sound.<ref name="hackert">{{cite web | title = Federal appeals court upholds $2.8M award for faulty smoke alarm | url = http://www.wthr.com/global/story.asp?s=8109077 | date = April 2, 2008 | first = Bob | last = Segall | website = WTHR.com | publisher = [[WTHR]] | access-date = 2008-10-28 | archive-url = https://web.archive.org/web/20081207064422/http://www.wthr.com/global/story.asp?s=8109077 | archive-date = December 7, 2008 }}</ref> The cause of the fire was a frayed electrical cord behind a couch that smoldered for hours before engulfing the house with flames and smoke.<ref name="hackert" /> The ionization smoke detector was found to be defectively designed, and in 2006 a jury in the United States District Court for the Northern District of New York decided that First Alert, and its then parent company, [[BRK Brands]], was liable for millions of dollars in damages.<ref name="hackert" />

=== Installation and placement ===
[[File:SmokeAlarmPlacement.svg|thumb|A 2007 U.S. guide to placing smoke detectors, suggesting that one be placed on every floor of a building, and in each bedroom]]

In the United States most [[U.S. state|state]] and [[Local government|local]] [[laws]] regarding the required number and placement of smoke detectors are based upon standards established in [[National Fire Protection Association|NFPA]] 72, National Fire Alarm and Signaling Code.<ref name=nfpa72>{{cite act|title=NFPA 72|number=72-2013|language=en|year=2013|url=http://www.nfpa.org/Assets/files/AboutTheCodes/72/72-13ROPDraft.pdf|access-date=6 August 2014|url-status=live|archive-url=https://web.archive.org/web/20140922234529/http://www.nfpa.org/Assets/files/AboutTheCodes/72/72-13ROPDraft.pdf|archive-date=22 September 2014}}</ref> Laws governing the installation of smoke detectors vary depending on the locality. However, some rules and guidelines for existing homes are relatively consistent throughout the developed world. For example, Canada and Australia require a building to have a working smoke detector on every level. The United States NFPA code, cited earlier, requires smoke detectors on every habitable level and within the vicinity of all bedrooms. Habitable levels include attics that are tall enough to allow access.<ref name=nfpa72/> Many other countries have comparable requirements.

In new construction, minimum requirements are typically more stringent. For example, all smoke detectors must be hooked directly to the [[electrical wiring]], be interconnected and have a [[battery backup]]. In addition, typically, smoke detectors are required either inside or outside every [[bedroom]], depending on local codes. Smoke detectors on the outside will detect fires more quickly, assuming the fire does not begin in the bedroom, but the sound of the alarm will be reduced and may not wake some people. Some areas also require smoke detectors in [[stairway]]s, main [[hallway]]s and [[garage (house)|garages]].<ref name="rcahw">{{cite book|last=Fletcher|first=Gregory|date=18 May 2011|title=Residential Construction Academy: House Wiring|url=https://books.google.com/books?id=ugOkSeJlfisC&q=placing+smoke+detectors|publisher=Technology & Engineering|isbn=978-1-111-30621-2|access-date=24 November 2014|url-status=live|archive-url=https://web.archive.org/web/20180508184806/https://books.google.com/books?id=ugOkSeJlfisC&dq=placing+smoke+detectors&source=gbs_navlinks_s|archive-date=8 May 2018}}</ref>

A dozen or more detectors may be connected via wiring or wirelessly such that if one detects smoke, the alarms will sound on all the detectors in the network, improving the likelihood that occupants will be alerted even if smoke is detected far from their location. Wired interconnection is more practical in new construction than for existing buildings.

In the UK, the installation of smoke alarms in new builds must comply with British Standard BS5839 pt6. BS 5839: Pt.6: 2004, which recommends that a new-build property consisting of no more than 3 floors (less than 200 square metres per floor) should be fitted with a Grade D, LD2 system. Building Regulations in England, Wales and Scotland recommend that BS 5839: Pt.6 should be followed, but as a minimum a Grade D, LD3 system should be installed. Building Regulations in Northern Ireland require a Grade D, LD2 system to be installed, with smoke alarms fitted in the escape routes and the main living room and a heat alarm in the kitchen; this standard also requires all detectors to have a mains supply and a battery backup.<ref>{{cite act|title=BS 5839-6:2013 Fire detection and fire alarm systems for buildings - Code of practice for the design, installation, commissioning and maintenance of fire detection and fire alarm systems in domestic premises|number=5839-6|language=en-GB|year=2013|url=http://www.safelincs.co.uk/pages/bs5839-6.html|access-date=24 November 2014|url-status=live|archive-url=https://web.archive.org/web/20141202161054/http://www.safelincs.co.uk/pages/bs5839-6.html|archive-date=2 December 2014}}</ref>