BRK electronic 4120 AC, 4120SB User Manual

USER’S MANUAL

SMOKE ALARMS

M06-2016-008 08/01

Models
4120SB, 4120B, 4120

AC Powered Ionization Smoke Alarm with

Battery Back-Up and Silence Feature

Cats. 4120SB, 4120SAB

Input: 120V AC, 60Hz, 0.05A

AC Powered Ionization Smoke Alarm

Cat. 4120

Input: 120V AC, 60Hz, 0.05A

Smoke particles of varying number and size are
produced in all fires.

Ionization technology is generally more
sensitive than photoelectric technology at
detecting small particles, which tend to be
produced in greater amounts by flaming fires,
which consume combustible materials rapidly
and spread quickly. Sources of these fires
may include paper burning in a wastebasket,
or a grease fire in the kitchen.

Photoelectric technology is generally more
sensitive than ionization technology at detect­ing large particles, which tend to be produced
in greater amounts by smoldering fires, which
may smolder for hours before bursting into
flame. Sources of these fires may include
cigarettes burning in couches or bedding.

For maximum protection, use both types of smoke
alarms on each level of your home.

AC Powered Ionization Smoke Alarm

with Battery Back-Up

Cats. 4120B, 4120AB

Input: 120V AC, 60Hz, 0.05A

OTHER FEATURES OF SMOKE ALARMS

Battery (DC) operated Smoke Alarms: Provide pro­tection even when electricity fails, provided the batter­ies are fresh and correctly installed. Units are easy to
install, and do not require professional installation.

AC powered Smoke Alarms: Can be interconnected
so if one unit senses smoke, all units alarm. They do
not operate if electricity fails. Units must be installed
by a qualified electrician.

AC/DC powered Smoke Alarms: (AC with battery
back-up): Can be interconnected so if one unit senses

smoke, all units alarm. They will operate if electricity fails,
provided the batteries are fresh and correctly installed.
Units must be installed by a qualified electrician.

Smoke alarms for the hearing impaired:

Special
purpose Smoke Alarms should be installed for the
hearing impaired. They include a visual alarm and an
audible alarm horn, and meet the requirements of the
Americans With Disabilities Act. These units can be
interconnected so if one unit senses smoke, all units
alarm. They do not operate if electricity fails. Units
must be installed by a qualified electrician. BRK
Electronics® Model 100S is an AC powered unit that
has an 85 decibel alarm and a 177 candela strobe
light, which flashes rapidly when the unit is in alarm.

All these units are designed to provide early warning
of fires if located, installed and cared for as described
in the user’s manual, and if smoke reaches them. If you
are unsure which type of unit to install, refer to NFPA
(National Fire Protection Association) 72 (National Fire
Alarm Code) and NFPA 101 (Life Safety Code). National
Fire Protection Association, One Batterymarch Park,
Quincy, MA 02269-9101. Also check your local building
codes which may also require specific units in new
construction or in different areas of the home.

TABLE OF CONTENTS

Where To Install Smoke Alarms . . . . . . . . . . . . . .1

Where Not To Install Smoke Alarms . . . . . . . . . . .3

Important! Read Before You Install

This Smoke Alarm . . . . . . . . . . . . . . . . . . . . . . . . .5

Understanding the Indicator Lights

and Alarm Horn Patterns . . . . . . . . . . . . . . . . . .6

Locking Features . . . . . . . . . . . . . . . . . . . . . . . . . .7

How To Install This Smoke Alarm . . . . . . . . . . . .10

Installing a Single (Stand Alone)

Smoke Alarm . . . . . . . . . . . . . . . . . . . . . . . . .11

Interconnecting Multiple Smoke Alarms . . . . .12

Testing and Maintenance . . . . . . . . . . . . . . . . . .14

If This Smoke Alarm Sounds . . . . . . . . . . . . . . .15

Using the Silence Feature

(Cat. 4120SB Only) . . . . . . . . . . . . . . . . . . . . . . . .16

Protecting Your Family From Fire . . . . . . . . . . . .17

What To Do In Case Of Fire . . . . . . . . . . . . . . . .18

If Your Smoke Alarm Needs Service . . . . . . . . .18

Troubleshooting . . . . . . . . . . . . . . . . . . . . . . . . . .19

Special Compliance Considerations . . . . . . . . .20

Limitations of Smoke Alarms . . . . . . . . . . . . . . .21

10-Year Limited Warranty . . . . . . . . . . . . . . . . . .22

IMPORTANT!

PLEASE READ CAREFULLY AND SAVE:

This user’s manual contains important
information about your Smoke Alarm’s
operation. If you are installing this unit for use
by others, you must leave this manual—or a
copy of it—with the user.

1

WHERE TO INSTALL SMOKE ALARMS

INSTALLING SMOKE ALARMS IN SINGLE-FAMILY AND MULTI-FAMILY RESIDENCES

The National Fire Protection Association (NFPA), recommends one Smoke Alarm on every floor, in every sleeping
area, and in every bedroom. In new construction, the Smoke Alarms must be AC powered and interconnected. See
“Agency Placement Recommendations” for details. For additional coverage, it is recommended that you install a
Smoke Alarm in all rooms, halls, storage areas, finished attics, and basements, where temperatures normally
remain between 40˚F (4˚C) and 100˚F (38˚C). Make sure no door or other obstruction could keep smoke from reach­ing the Smoke Alarms.

KEY:

BEDROOM

HALL

LIVING ROOM KITCHEN

NEW CONSTRUCTION

MULTI-STORY RESIDENCE

BEDROOM

LIVING ROOM KITCHEN

HALL

EXISTING HOMES

MULTI-STORY RESIDENCE

BEDROOM

FINISHED BASEMENT

BEDROOM

FINISHED BASEMENT

BEDROOM

BEDROOM

SINGLE-STORY RESIDENCE, APARTMENT,
MOBILE HOME

SINGLE-STORY RESIDENCE, APARTMENT,
MOBILE HOME

KITCHEN

BEDROOM

KITCHEN

BEDROOM

DINING ROOM

LIVING ROOM

DINING ROOM

LIVING ROOM

REQUIRED TO MEET
NFPA RECOMMENDATIONS

RECOMMENDED FOR
ADDITIONAL PROTECTION

SMOKE ALARMS WITH SILENCE
FEATURES RECOMMENDED FOR
ADDITIONAL PROTECTION

INTERCONNECTED AC OR
AC/DC SMOKE ALARMS

KEY:

REQUIRED TO MEET
NFPA RECOMMENDATIONS

RECOMMENDED FOR
ADDITIONAL PROTECTION

SMOKE ALARMS WITH SILENCE
FEATURES RECOMMENDED FOR
ADDITIONAL PROTECTION

2

More specifically, install Smoke Alarms:

• On every level of your home, including finished
attics and basements.

• Inside every bedroom, especially if people sleep
with the door partly or completely closed.

• In the hall near every sleeping area. If your home
has multiple sleeping areas, install a unit in
each. If a hall is more than 12 meters long
(40 feet), install a unit at each end.

• At the top of the first-to-second floor stairway,
and at the bottom of the basement stairway.

Specific requirements for Smoke Alarm installation
vary from state to state and from region to region.
Check with your local Building Inspector and/or Fire
Department for current requirements in your area. If
you install AC or AC/DC units, it is recommended
(and may be required) they be interconnected for
added protection.

Installing Smoke Alarms in Mobile Homes

For minimum security install one Smoke Alarm as close
to each sleeping area as possible. For more security,
put one unit in each room. Many older mobile homes
(especially those built before 1978) have little or no
insulation. If your mobile home is not well insulated, or
if you are unsure of the amount of insulation, it is
important to install units on inside walls only. Smoke
Alarms should be installed where temperatures normal­ly remain between 40˚F (4˚C) and 100˚F (38˚C).

This equipment should be installed in accordance with
NFPA (National Fire Protection Association) 72 and

101.

National Fire Protection Association, One Batterymarch
Park, Quincy, MA 02269-9101. Additional local build-

ing and regulatory codes may apply in your area.
Always check compliance requirements before
beginning any installation.

Smoke Alarms Recommended In Hotels, Motels,
Hospitals, Extended Care Facilities

Install stand-alone (non-interconnected) AC powered
Smoke Alarms with battery back-up for maximum
protection in each sleeping room.

AGENCY PLACEMENT
RECOMMENDATIONS

NFPA 72 (National Fire Code)

Smoke Alarms shall be installed in each separate sleep­ing room, outside each sleeping area in the immediate
vicinity of the bedrooms and on each additional story of
the family living unit, including basements and exclud­ing crawl spaces and unfinished attics.

In new construction, Alarms shall be so arranged that
operation of any one Alarm shall cause the operation of
all Alarms within the dwelling.

Smoke Detection-Are More Smoke Alarms Desirable?
The required number of Smoke Alarms might not pro-

INDIVIDUAL ROOMS

HALLWAY

RECOMMENDED STAND-ALONE
(NON-INTERCONNECTED)SMOKE ALARMS

LOBBY

3

vide reliable early warning protection for those areas
separated by a door from the areas protected by
the required Smoke Alarms. For this reason, it is
recommended that the householder consider the use of
additional Smoke Alarms for those areas for increased
protection. The additional areas include the basement,
bedrooms, dining room, furnace room, utility room, and
hallways not protected by the required smoke alarms.
The installation of Smoke Alarms in kitchens, attics
(finished or unfinished), or garages is not normally
recommended, as these locations occasionally experi­ence conditions that can result in improper operation.

California State Fire Marshal (CSFM)

Early warning detection is best achieved by the
installation of fire detection equipment in all rooms and
areas of the household as follows: A Smoke Alarm
installed in each separate sleeping area (in the vicinity,
but outside bedrooms), and Heat or Smoke Alarms in
the living rooms, dining rooms, bedrooms, kitchens,
hallways, finished attics, furnace rooms, closets, utility
and storage rooms, basements, and attached garages.

WHERE NOT TO INSTALL SMOKE ALARMS

For best performance, do not install the unit:

• Where combustion particles are produced.
Combustion particles form when something
burns. Areas to avoid include poorly ventilated
kitchens, garages, and furnace rooms. Keep
units at least 20 feet (6 meters) from the sources
of combustion particles (stove, furnace, water
heater, space heater) if possible. Ventilate these
areas as much as possible.

• In air streams near kitchens. Air currents can
draw cooking smoke into the sensing chamber
of a smoke alarm near the kitchen.

• In very damp, humid or steamy areas, or directly
near bathrooms with showers. Keep units at
least 10 feet (3 meters) away from showers,
saunas, dishwashers, etc.

• Where the temperatures are regularly below 40˚F
(4˚ C) or above 100˚ F (38˚ C) including unheated
buildings, outdoor rooms, porches, or unfinished
attics or basements.

• In very dusty, dirty, or greasy areas. Do not
install a smoke alarm directly over the stove or
range. Clean a laundry room unit frequently to
keep it free of dust or lint.

• Near fresh air vents, ceiling fans, or in very
drafty areas. Drafts can blow smoke away
from the unit, preventing it from reaching the
sensing chamber.

• In insect infested areas. Insects can clog
openings to the sensing chamber and cause
unwanted alarms.

• Less than 12 inches (305 mm) away from
fluorescent lights. Electrical “noise” can interfere
with the sensor.

• In “dead air” spaces. “Dead air” spaces may
prevent smoke from reaching the smoke alarm.

4

AVOIDING DEAD AIR SPACES

“Dead air” spaces may prevent smoke from reach­ing the Smoke Alarm. To avoid dead air spaces,
follow the installation recommendations below.

On ceilings,

install Smoke Alarms as close to the
center of the ceiling as possible. If this is not possible,
install the Smoke Alarm at least 4 inches (102 mm)
from the wall or corner.

For wall mounting (if allowed by building codes), the
top edge of Smoke Alarms should be placed between
4 inches (102 mm) and 12 inches (305 mm) from the
wall/ceiling line, below typical “dead air” spaces.

On a peaked, gabled, or cathedral ceiling, install
the first Smoke Alarm within 3 feet (0.9 meters) of the
peak of the ceiling, measured horizontally. Additional
Smoke Alarms may be required depending on the
length, angle, etc. of the ceiling's slope. Refer to
NFPA 72 for details on requirements for sloped or
peaked ceilings.

FOR STANDARD, FLAT CEILINGS

Best Location 

3 ft

(0.9m)

3 ft

(0.9m)

4"

(center of ceiling)
Acceptable 

Location

Dead Air Spaces
(4" or 102 mm)



Install first 
smoke alarm 
in this target area

If required, 
install additional 
smoke alarms 
along the slope.

Install first 
smoke alarm 
in this target area

If required, 
install additional 
smoke alarms 
along the slope.

4"

Do not install top of 

smoke alarm lower than 

12" (305 mm) from the 

wall/ceiling line

FOR SLOPED CEILINGS

(i.e. great rooms, condominiums, dormers)

FOR PEAKED CEILINGS

(i.e. Cathedral ceilings, A-frames)



5

Read “Where To Install Smoke Alarms” and “Where
Not To Install Smoke Alarms” before beginning. This
unit monitors the air, and when smoke reaches its
sensing chamber, it alarms. It can give you more time
to escape before fire spreads. This unit can ONLY
give an early warning of developing fires if it is
installed, maintained and located where smoke can
reach it, and where all residents can hear it, as
described in this manual. This unit will not sense gas,
heat, or flame. It cannot prevent or extinguish fires.

ELECTRICAL SHOCK HAZARD. Turn off power to
the area where you will install this unit at the circuit
breaker or fuse box before beginning installation.
Failure to turn off the power before installation may
result in serious electrical shock, injury or death.

This unit will not alert hearing impaired residents. It
is recommended that you install special units which
use devices like flashing strobe lights to alert hear­ing impaired residents.

Installation of this unit must conform to the electri­cal codes in your area; Article 760 of NFPA 70 (NEC),
NFPA 72, NFPA 101; SBC (SBCCI); UBC (ICBO); NBC
(BOCA); OTFDC (CABO), and any other local or
building codes that may apply. Wiring and installa­tion must be performed by a licensed electrician.
Failure to follow these guidelines may result in injury
or property damage.

This unit must be powered by a 24-hour, 120VAC
60Hz circuit. Be sure the circuit cannot be turned
off by a switch, dimmer, or ground fault circuit inter­rupter. Failure to connect this unit to a 24-hour circuit
may prevent it from providing constant protection.

This Smoke Alarm must have AC or battery power
to operate.

On Models 4120SB and 4120B Only:
If the AC power fails, battery back-up will allow the
alarm to sound for at least 4 minutes. If AC power
fails and the battery is weak, protection should last
for up to 7 days. If AC power fails and the battery is
dead or missing, the alarm cannot operate.

It is possible an electrical fire could occur on the
circuit powering this unit. If this happened, the power
to the unit could be cut off and it may fail to alarm.
Some safety experts recommend wiring warning
devices like this unit on separate circuits from other
appliances, since these circuits are not as likely to be
overloaded. Other safety experts recommend wiring
these units on the same circuits as appliances so it is
more readily apparent if the circuit fails. Whichever
circuit you choose, it is recommended you also install
battery powered units as back-ups in case of fire on
the circuit powering the AC powered units.

IMPORTANT! READ BEFORE YOU INSTALL THIS SMOKE ALARM

Continued...

6

Read Before You Install This Smoke Alarm (continued)...

Never disconnect the power from an AC powered
unit to stop an unwanted alarm. Doing so will disable
the unit and remove your protection. In the case of a
true unwanted alarm open a window or fan the
smoke away from the unit. The alarm will reset auto­matically when it returns to normal operation. Never
remove the batteries from a battery operated unit to
stop an unwanted alarm (caused by cooking smoke,
etc.). Instead open a window or fan the smoke away
from the unit. The alarm will reset automatically.

Connect this unit ONLY to other compatible units.
See “How To Install This Smoke Alarm” for details.
Do not connect it to any other type of alarm or auxil­iary device. Connecting anything else to this unit
may damage it or prevent it from operating properly.

Do not stand too close to the unit when the alarm
is

sounding. It is loud to wake you in an emergency.
Exposure to the horn at close range may harm your
hearing. When testing the unit, step back when the
horn starts sounding.

Do not paint over the unit. Paint may clog the
openings to the sensing chamber and prevent the
unit from operating properly.

On Models 4120SB and 4120B Only:
The battery compartment will not close unless a
battery is installed. This warns you the unit will not
operate under DC power without a battery.

UNDERSTANDING THE INDICATOR LIGHTS AND ALARM HORN PATTERNS

NOTE: When power is applied, unit(s) may alarm momentarily.

*When any Smoke Alarm in an interconnected series triggers an alarm, its red LED will flash rapidly. The red LEDs will
remain OFF on any remaining alarms in the series. This feature helps responders identify which unit(s) triggered the alarm.

AC Power
4120SB, 4120B, 4120

DC Power
4120SB, 4120B

Normal Operation

Constant Green LED
Flashing Red LED
No Audible Alarm

Green LED Off
Flashing Red LED
No Audible Alarm

Test Condition

Constant Green LED
Rapidly Flashing LED
Audible Alarm

Green LED Off
Rapidly Flashing LED
Audible Alarm

Alarm Condition*
(Initiating Unit)

Constant Green LED
Rapidly Flashing Red LED
Audible Alarm

Green LED Off
Rapidly Flashing LED
Audible Alarm