MA Smoke Detector Rules And Ionization Vs. Photoelectric Smoke Detectors

Single family and 2-family homes sold in MA must be inspected by the fire department to verify the proper installation of smoke detectors and carbon monoxide detectors. They then provide a smoke certificate required for the closing. It is prudent for property owners to know the MA smoke detector rules and ionization vs. photoelectric smoke detectors and to be in compliance (regardless of whether they are selling their property).

Ionization Vs. Photoelectric Smoke Detectors

There are two primary kinds of smoke detectors, ionization and photoelectric. Each one has different strengths and weaknesses relating to recognizing smoke and fire.

Ionization Detectors

Ionization smoke detectors have two electrodes and a constant current that runs between them. Smoke interferes with this constant current and sets off the alarm. This kind of smoke detector is good at detecting flames but does not differentiate between smoke and steam. Therefore, they are likely to issue false alarms if placed near kitchens and bathrooms.

Photoelectric Smoke Detectors

Photoelectric smoke detectors have a beam of light. Smoke or fire can break up the beam and activate the alarm. It is more accurate at recognizing smoldering fire and is less sensitive to false alarms from cooking smoke or shower steam.

MA Smoke Detector Rules

MA regulations determine the types and placement of smoke detectors in residential properties. The rules differ based on when a property was built or significantly improved. Below is an overview of the location of smoke detectors inside a residence.

Location before 1975 1975 to Aug. 27, 1997 after Aug. 27, 1997 on or after Jan. 1, 2008 on or after Feb. 4, 2011
Power Supply Hardwired
Battery Backup
Battery Backup
Battery Backup
Every Finished Level Yes Yes Yes Yes Yes
Base of Every Stairway Yes Yes Yes Yes
Outside Each Sleeping Space Yes Yes Yes Yes Yes
Minimum 1 for Every 1,200 sq.ft. Finished Space per Floor Yes Yes Yes Yes
Inside All Bedrooms Yes Yes Yes
In Basement Yes
Bottom of Every Stairway to an Occupied Floor Yes
Within 20ft. of Kitchens/Baths Photoelectric Photoelectric Photoelectric Photoelectric
Outside of 20ft. of Kitchens/Baths Both Ionization & Photoelectric Photoelectric OR Dual Photoelectric

Additional Information

Additional details on MA smoke detector rules may be viewed at Note that this information is just an introduction, should not be interpreted as legal advice and may change without notice. Additionally, cities and towns may impose stricter rules beyond state mandated ones. Contact your local fire department for comprehensive and current information for your home.

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About Editor-John P. Wells

I am a resident of Newburyport and have worked in education, high tech and urban development. My interests in architecture and construction are invaluable to my clients. For more information please visit the Wellsco website.