BRK electronic 4120B User manual

•
AC Powered Ionization Smoke Alarm
with Battery Back-Up and
Silence Feature
Cat. 4120SB
Input: 120V AC, 60Hz, 0.5A
AC Powered Ionization Smoke Alarm
with Battery Back-up
Cat. 4120B
Input: 120V AC, 60Hz, 0.5A
Model
4120B
4120SB M06-2016-007 06/00
User’s Manual
Smoke Alarms
Ionization smoke alarms are generally more effective at detecting 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 smoke alarms are generally more effective at detecting smoldering fires which 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.

INSIDE THIS MANUAL
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
Optional 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. . . . BACK COVER
IMPORTANT!
PLEASE READ CAREFULLY AND SAVE.
This user’s manual contains important information
about your smoke alarm’s operation. If you are
installing this smoke alarm for use by others, you
must leave this manual--or a copy of it--with the
end user.
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
®
Cat. 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 Chapter 2 of the National Fire
Protection Association (NFPA) Standard 72 (National Fire
Alarm Code) and NFPA 101 (Life Safety Code). National Fire
Protection Association, One Batterymarch Park, Quincy, MA
02269-9101. Local building codes may also require specific
units in new construction or in different areas of the home.

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
.
BEDROOM
BEDROOM HALL
LIVING ROOM KITCHEN
FINISHED BASEMENT
REQUIRED TO MEET
NFPA RECOMMENDATIONS
RECOMMENDED FOR
ADDITIONAL PROTECTION
BEDROOM
BEDROOM
KITCHEN
LIVING ROOM
DINING ROOM
MULTI-STORY RESIDENCE
SINGLE-STORY RESIDENCE, APARTMENT,
MOBILE HOME
KEY:
EXISTING HOMES
SMOKE ALARMS WITH SILENCE
FEATURES RECOMMENDED FOR
ADDITIONAL PROTECTION
INTERCONNECTED AC OR
AC/DC SMOKE ALARMS
BEDROOM
BEDROOM HALL
LIVING ROOM KITCHEN
FINISHED BASEMENT
REQUIRED TO MEET
NFPA RECOMMENDATIONS
RECOMMENDED FOR
ADDITIONAL PROTECTION
BEDROOM
BEDROOM LIVING ROOM
DINING ROOM
MULTI-STORY RESIDENCE
SINGLE-STORY RESIDENCE, APARTMENT,
MOBILE HOME
KEY:
NEW CONSTRUCTION
SMOKE ALARMS WITH SILENCE
FEATURES RECOMMENDED FOR
ADDITIONAL PROTECTION
KITCHEN

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 40 feet long (12
meters), install a unit at each end.
• At the top of the first-to-second floor stairway,
and at the bottom of the basement stairway.
IMPORTANT!
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) .
IMPORTANT!
This equipment should be installed in accordance
with the National Fire Protection Association’s
Standard 72.
National Fire Protection Association,
One Batterymarch Park, Quincy, MA 02269-9101.
Additional local building 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
Agency Placement Recommendations
NFPA Standard 72 Section 2-2.1.1.1
2-2.1.1.1 Smoke alarms shall be installed outside of
each separate 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
a smoke alarm shall also be installed in each sleeping
room. Chapter 2 also reads as follows: 2-2.2.1: In new
construction, where more than one smoke alarm is
required by 2-2.1, alarms shall be so arranged that
operation of any one alarm shall cause the operation of
all alarms within the dwelling. A-2.5.2.1 Smoke
Detection-Are More Smoke Alarms Desirable? The
required number of smoke alarms might not provide
RECOMMENDED STAND-ALONE
(NON-INTERCONNECTED)SMOKE ALARMS
HALLWAY
INDIVIDUAL ROOMS
LOBBY
Install stand-alone (non-interconnected)
AC powered smoke alarms with battery back-up
for maximum protection in each sleeping room.

3
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 Marshall
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, sau-
nas, 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 open-
ings to the sensing chamber and cause
unwanted alarms.
• Less than 12 inches (305 mm) away from fluo-
rescent 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
FOR PEAKED CEILINGS
(i.e. Cathedral ceilings, A-frames)
Best Location
(center of ceiling)
Acceptable
Location
Dead Air Spaces
(4" or 102 mm)
4"
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)
3 ft
Install first
smoke alarm
in this target area
If required,
install additional
smoke alarms
along the slope.
3 ft
Install first
smoke alarm
in this target area
If required,
install additional
smoke alarms
along the slope.
(0.9m)
(0.9m)

5
Important! Read Before You Install This Smoke Alarm
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. DANGER!
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.
WARNING!
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.
WARNING!
Installation of this unit must conform to the electrical
codes in your area; Article 760 of the National
Electrical Code (NFPA 70), NFPA 72, 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.
WARNING!
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
.
WARNING!
This alarm must have AC or battery power to operate. If
the AC power fails, battery back-up will allow the alarm
to sound for at least 4 minutes (if 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.
WARNING!
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.
WARNING!
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.

6
CAUTION!
Connect this unit ONLY to other compatible units.
See “How To Install and Interconnect 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.
CAUTION!
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.
CAUTION!
Do not paint over the unit. Paint may clog the
openings to the sensing chamber and prevent the
unit from operating properly.
CAUTION!
The battery door 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
Normal Operation Test Condition Alarm Condition*
(Initiating Unit)
AC Power Constant Green LED
Flashing Red LED
No Audible Alarm
Constant Green LED
Rapidly Flashing Red LED
Audible Alarm
Constant Green LED
Rapidly Flashing Red LED
Audible Alarm
DC Power Green LED Off
Flashing Red LED
No Audible Alarm
Green LED Off
Rapidly Flashing LED
Audible Alarm
Green LED Off
Rapidly Flashing LED
Audible Alarm
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.

7
Important Installation Parts
The Mounting Bracket : To
remove the mounting
bracket from the smoke
alarm base, hold the smoke
alarm base firmly and twist
the mounting bracket off.
The mounting bracket
installs onto the junction
box. It has a variety of screw
slots to fit most boxes.
The Power Connector: The power
connector plugs into a power input block
on the smoke alarm. It supplies the unit
with AC power.
•The black wire is “hot.”
•The white wire is neutral.
•The orange wire is used for interconnect.
If you need to remove the power
connector, insert a flat screwdriver blade
between the power connector and the
security tab inside the power input block.
Gently pry back the tab and pull the
connector free.
Optional Locking Features
The optional locking features are designed to
prevent unauthorized removal of the battery or
alarm. It is not necessary to activate the locks in
single-family households where unauthorized
battery or alarm removal is not a concern.
These smoke alarms have two separate locking
features: one to lock the battery compartment, and
the other to lock the smoke alarm to the mounting
bracket. You can choose to use either feature
independently, or use them both.
Tools you will need: • Needle-nose pliers or utility
knife • Standard/Flathead screwdriver.
Both locking features use
locking pins, which are
molded into the mounting
bracket. Using needle
nose pliers or a utility
knife, remove one or both
pins from the mounting
bracket, depending on
how many locking
features you want to use.
IMPORTANT!
To permanently remove either lock insert a
flathead screwdriver between the locking pin and
the lock, and pry the pin out of the lock.
Locking Pin

8
To Lock The Battery Compartment
IMPORTANT!
Do not lock the battery compartment until you have
activated the battery and tested the battery back-up.
1. Activate the battery
back-up by removing
the “Pull to Activate
Battery Back-Up” tab.
2. Push and hold test
button until the alarm
sounds: 3 beeps,
pause, 3 beeps, pause.
If the unit does not alarm during testing, DO NOT
lock the battery compartment! Install a new battery
and test again. If the smoke alarm still does not
alarm, replace it immediately.
3. Using needle-nose pliers
or a utility knife, detach
one locking pin from the
mounting bracket.
4. Push the locking pin
through the black dot on the label on the back of
the smoke alarm.
To Un-Lock The Battery Compartment
IMPORTANT!
Once the smoke alarm is installed, you must
disconnect it from the AC power before unlocking the
battery compartment.
DANGER!
ELECTRICAL SHOCK HAZARD. Turn off the power to
the area where the smoke alarm is installed before
removing it from the mounting bracket. Failure to
turn off the power first may result in serious
electrical shock, injury or death.
WARNING!
Always discharge the branch circuit before servicing
an AC or AC/DC smoke alarm. First, turn off the AC
power at the circuit breaker or fuse box. Next, remove
the battery from smoke alarms with battery back-up.
Finally, press and hold the test button for 5-10
seconds to discharge the branch circuit.
1. Remove the smoke alarm from the mounting
bracket. If the unit is locked to the bracket, see
the section “To deactivate the locking feature.”
2. Disconnect the power connector by gently prying
it away from the back of the smoke alarm.
3. Insert a flathead
screwdriver under
the head of the
locking pin, and
gently pry it out of
the battery
compartment lock.
(If you plan to relock
the battery
compartment, save
the locking pin.)

9
4. To relock the battery compartment, close the
battery door and reinsert locking pin in lock.
5. Reconnect the power connector to the back of the
smoke alarm, reattach the smoke alarm to the
mounting bracket, and restore the power.
IMPORTANT!
When replacing the battery, always test the smoke
alarm before relocking the battery compartment.
To Lock The Mounting Bracket :
1. Using needle-nose
pliers, detach one
locking pin from the
mounting bracket.
2. Insert the locking pin into the lock located on
the pivoting hinge of the battery door.
3. When you attach the smoke alarm to the
mounting bracket, the locking pin’s head will
fit into a notch on the bracket.
To Un-Lock The Mounting Bracket :
DANGER!
ELECTRICAL SHOCK HAZARD. Turn off the power
to the area where the smoke alarm is installed
before removing it from the mounting bracket.
Failure to turn off the power first may result in
serious electrical shock, injury or death.
WARNING!
Always discharge the branch circuit before
servicing an AC or AC/DC smoke alarm. First,
turn off the AC power at the circuit breaker or
fuse box. Next, remove the battery from smoke
alarms with battery back-up. Finally, press and
hold the test button for 5-10 seconds to
discharge the branch circuit
.
1. Insert a flathead
screwdriverbetweenthe
mounting bracket pin
and the mounting
bracket.
2. Pry the smoke alarm away from the bracket
by turning both the screwdriver and the
smoke alarm clockwise (right) at the same
time.

10
How To Install This Smoke Alarm
This unit is designed to be mounted on any standard
wiring junction box up to a 4-inch diagonal size, on
either the ceiling or wall. Read “Where to Install” and
“Where Not To Install” smoke alarms before you
begin installation. If a junction box is not already in
place, install one using standard #12 or #14 gauge
solid copper Appliance Wiring Material.
IMPORTANT!
Activate the battery back-up by removing the “Pull
to Activate Battery Back-Up” tab. You do not need
to open the battery compartment and reposition the
battery during installation.
When the battery is activated, the red light will
shine continuously for 5-10 seconds, then begin
to flash about once a minute.
Test the battery back-up. Press and hold the test
button on the cover until the alarm sounds.
The Parts Of This Unit
1 Mounting bracket
2 Mounting slots and screws
3 Optional locking pins
(break out of bracket)
4 Hot (black) AC wire
5 Neutral (white) AC wire
6 Interconnect wire
7 Latch to open battery compartment
8 Swing-out battery compartment
9 Quick-connect power connector
1
2
3
2
9
8
7
3
5
6
4

11
Installing a Single
(Stand-Alone) Smoke Alarm
Tools you will need: Standard/Flathead screwdriver
DANGER!
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.
To install this unit, follow these steps:
1. Remove the mounting bracket from the base,
and attach it to the junction box.
2. Using wire nuts, connect the power connector to
the household wiring.
• Connect the white wire on the power connector
to the neutral wire in the junction box.
• Connectthe blackwireon thepower connector
to the hot wire in the junction box.
• Tuck the orange wire inside the junction
box. It is used for interconnect only.
3.
Plug the power connector
into the back of the smoke
alarm.
4. Position the base of the alarm over the mounting
bracket and turn. The alarm can be positioned
over the bracket every 60°. Turn the smoke alarm
clockwise (right) until the unit is in place.
5. If you are only installing one unit, restore power
to the junction box.
6. Make sure the unit is receiving AC power. Under
normal operation, the Green power indicator light
will shine continuously.
7. If the Green power indicator light does not light,
TURN OFF POWER TO THE JUNCTION BOX
and recheck all connections. If all connections
are correct and the Green power indicator still
does not light when you restore the power, the
unit should be replaced immediately.
IMPORTANT!
Cat. 4120SB Only: During installation, if you
accidentally press the Silence button, the alarm will
“chirp” once a minute for up to 15 minutes and the
Test feature will be temporarily disabled. This is
normal. The “chirping” will stop once the alarm
returns to normal operation.
DANGER!
ELECTRICAL SHOCK HAZARD. Do not restore
power until all smoke alarms are completely
installed. Restoring power before installation is
complete may result in serious electrical
shock, injury or death.

12
Interconnecting Multiple
Smoke Alarms
Interconnected units can provide earlier warning of
fire than stand-alone units, especially if a fire starts
in a remote area of the dwelling. If any unit in the
series senses smoke, all units will alarm. To
determine which smoke alarm initiated an alarm, see
table:
All wiring must conform to all local electrical codes
and Article 760 of the National Electrical Code (NFPA
70). Refer to NFPA 72, Chapter 2 and/or your local
building code for further connection requirements.
WARNING!
AC and AC/DC smoke alarms can be
interconnected. Under AC power, all units will
alarm when one senses smoke. When power is
interrupted, only the AC/DC units in the series will
continue to send and receive signals. AC powered
smoke alarms will not operate.
IMPORTANT!
Interconnect units within a single family residence
only. Otherwise all households will experience
unwanted alarms when you test any unit in the
series.
Interconnected units will only work if they are wired
to compatible units and all requirements are met.
This unit is designed to be compatible with:
BRK Electronics
®
Smoke Alarms 100S, 2002RAC,
4120B, 4120SB, 4919, 5919, 5919TH, 86RAC;
BRK Electronics
®
Heat Alarm HD6135F; and
First Alert
®
Smoke Alarms SA4120B, SA4121B,
SA4919B, SA86B, SA100B.
Interconnected units must meet ALL of the
following requirements:
• A maximum of 18 units total may be intercon-
nected (Maximum of 12 smoke alarms).
• The same fuse or circuit breaker must power all
interconnected units.
• The total length of wire interconnecting the
units should be less than 1000 feet (300
meters). The interconnect wire should be
#18 gauge or larger, rated at least 300V.
•If an interconnect wire is not already part of your
household wiring, you will need to install one.
This type of wire is commonly available at Hard-
ware and Electrical Supply stores.
WARNING!
Failure to meet any of the above requirements
could damage the units and cause them to
malfunction, removing your protection.
On Initiating Alarm(s) Red LED(s) flashes(flash)
rapidly
On All Other Alarms Red LED is Off

13
Interconnecting Multiple Smoke Alarms
To install and interconnect multiple alarms:
1. Remove mounting bracket from the base.
Position screw slots on mounting bracket over
screws in the junction box. Tighten screws.
2. Strip off about 1/2” (12 mm) of the plastic coating
on the orange wire on the power connector.
3. Using wire nuts, connect the power connector to
the household wiring.
• Connect the white wire on the power connector
to the neutral wire in the junction box.
• Connectthe blackwireon thepower connector
to the hot wire in the junction box.
• Connect the orange wire on the power connec-
tor to the interconnect wire in the junction box.
Repeat for each unit you are interconnecting.
Never connect the hot or neutral wires in the
junction box to the orange interconnect wire.
4. Plug the power connector into the back of the
smoke alarm.
5. Position the base of the alarm over the mounting
bracket and turn. The alarm can be positioned
over the bracket every 60°. Turn the unit
clockwise (right) until the unit is in place.
DANGER!
ELECTRICAL SHOCK HAZARD. Do not restore
power until all smoke alarms are completely
installed. Restoring power before installation is
complete may result in serious electrical shock,
injury or death.
6. Make sure each unit is receiving AC power.
Under normal operation, the green power
indicator light will shine continuously.
7. Test each smoke alarm. Press and hold the test
button until the unit alarms.
When testing a series of interconnected units
you must test each unit individually. Make sure
all units alarm when each one is tested.
NOTE: When power is applied, unit(s) may alarm
momentarily.
IMPORTANT!
If any unit in the series does not alarm, TURN OFF
POWER and recheck connections. If it does not
alarm when you restore power, replace it immediately.
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A Unswitched 120V AC
60Hz source 4 Wire nut
B To additional units
Maximum = 18 (Max.
12 smoke alarms)
5 Junction box
1 Smoke alarm 6 Neutral (white) AC wir
e
2 Ceiling or wall 7 Interconnect wire
3 Power connector 8 Hot (black) AC wire

14
IMPORTANT!
Cat. 4120SB Only: During installation, if you
accidentally press the Silence button, the alarm will
“chirp” once a minute for up to 15 minutes and the
Test feature will be temporarily disabled. This is
normal. The “chirping” will stop once the alarm
returns to normal operation.
Testing and Maintenance
Weekly Testing
WARNING!
NEVER use an open flame of any kind to test this unit.
You might accidentally damage or set fire to the unit or
to your home. The built-in test switch accurately tests
the unit’s operation as required by Underwriters
Laboratories, Inc. (UL). If you choose to use an aerosol
smoke product to test the smoke alarm, be certain to
use one that has been Listed to Underwriters
Laboratories, Inc. Safety Standards, and use it only as
directed. Use of non-UL Listed products or improper
use of UL Listed products may affect the smoke alarm’s
sensitivity
.
It is important to test this unit every week to make
sure it is working properly. Using the test button is
the recommended way to test this smoke alarm.
Press and hold the test button on the cover of the unit until
the alarm sounds (the unit may continue to alarm for a few
seconds after you release the button). If it does not alarm,
make sure the unit is receiving power and test it again. If it
still does not alarm, replace it immediately.
During
testing, you will hear a loud, repeating horn
pattern: 3 beeps, pause, 3 beeps, pause.
When testing a series of interconnected units you
must test each unit individually. Make sure all units
alarm when each one is tested.
Regular Maintenance
This unit has been designed to be as maintenance-
free as possible, but there are a few simple things
you must do to keep it working properly:
• Test it at least once a week.
• Gently vacuum off any dust on the cover at
least once a month using your vacuum’s soft
brush attachment. Test the unit after vacuum-
ing the cover.
• Never use water, cleaners or solvents since
they may damage the unit.
• Relocate the unit if it sounds frequent
unwanted alarms. See “Where Not To Install
Smoke Alarms” for details.
• When the battery back-up becomes weak, the
smoke alarm will “chirp” about once a minute
(the low battery warning). This warning should
last 7 days, but you should replace the battery
immediately to continue your protection.
Choosing a replacement battery:
Your smoke alarm’s battery back-up requires one
standard 9V battery. The following batteries are
acceptable as replacements. This list supplements
the list on the smoke alarm battery door: Eveready
#216, #522 (Energizer), #1222; Duracell #MN1604,
MX1604 (Ultra); Gold Peak #1604P, #1604S;
Rayovac 1604, D1604. You may also use a Lithium
battery like the Ultralife U9VL-J for longer service life
between battery changes. These batteries are
available at many local retail stores.

15
IMPORTANT!
Most carbon zinc batteries have an average service
life of 1 year; most alkaline batteries have an average
service life of 1-2 years; most Lithium batteries have
an average service life of 6-10 years. Actual service
life depends on the smoke alarm and the
environment in which it is installed. All the batteries
specified above are acceptable replacement
batteries for this unit. Regardless of the
manufacturer’s suggested battery life, you MUST
replace the battery immediately once the unit starts
“chirping” (the “low battery warning”).
If This Smoke Alarm
Sounds
If the alarm sounds and you are not testing it, it is
warning you of a potentially dangerous situation
that requires your immediate attention.
WARNING!
NEVER ignore any alarm. Ignoring the alarm may
result in injury or death. If the unit alarms and you
are not absolutely certain of the source of the
smoke, get everyone out of the house immediately.
Responding To An Alarm
If the unit alarms and you are not absolutely certain of
the source of the smoke, get everyone out of the
dwelling immediately. Stay calm and follow your family
escape plan. Stay as low to the ground as possible,
and cover your mouth with a damp cloth. Never open
a door before testing to see if it is hot. Call the Fire
Department from outside, and give them your address
then name. Read “What To Do In Case Of Fire” at the
end of this manual for more information.
If the unit alarms and you are certain that the source
of smoke is not a fire—cooking smoke or an
extremely dusty furnace, for example—open a
nearby window or door and fan the smoke away
from the unit (Model 4120SB only: use the Silence
Feature to silence the alarm). This will silence the
alarm, and once the smoke clears the unit will reset
itself automatically.
N
OTE:
When an interconnected system of AC powered units
is in alarm, the alarm indicator light on the unit(s) that
initiated the alarm will blink rapidly. It will remain OFF
on any remaining units.
CAUTION!
Never disconnect the AC power to quiet an
unwanted alarm. Disconnecting the power disables
the alarm so it cannot sense smoke. This will
remove your protection.
DANGER!
ELECTRICAL SHOCK HAZARD: Attempting to
disconnect the power connector from the unit
when the power is on may result in electrical
shock, serious injury or death.

16
Cat. 4120SB Only—
Using The Silence Feature
The silence feature on this unit can temporarily quiet
an unwanted alarm for several minutes.
CAUTION!
The silence feature does not disable the unit—it
makes it temporarily less sensitive to smoke. For
your safety, if smoke around the unit is dense
enough to suggest a potentially dangerous
situation, the unit will stay in alarm or may re-alarm
quickly. If you do not know the source of the
smoke, do not assume it is an unwanted alarm.
Not responding to a fire can result in property loss,
injury, or death.
IMPORTANT!
While the unit is in the “silence mode,” the test
button will not operate. The alarm cannot be tested
while in the silence mode.
To silence smoke alarms
in an interconnected series:
1. To silence multiple alarms in an interconnected
series, you must press the silence button on the
unit(s) that triggered the alarm.
N
OTE:
The red light under the silence button on the initiating
alarm will flash rapidly. The red light will be off on all
other smoke alarms.
2. Once you activate the silence feature, you will
hear a reminder “chirp” on the initiating alarm
about once a minute (for up to 15 minutes).
3. While the units are in the “silence mode,” the test
buttons will not operate. The alarms cannot be
tested while in the silence mode.
4. The “chirping” on the initiating alarm will stop
once the unit returns to normal operation.
IMPORTANT!
The silence feature on these units can temporarily
quiet an unwanted alarm fo several minutes. To use
this feature, press the “Push to Silence” button on
the cover. Once you activate it, you will hear a
reminder “chirp” about once a minute (for up to 15
minutes) and the Test feature is temporarily
disabled. The “chirping” will stop once the unit
returns to normal operation. If the unit will not
silence and no heavy smoke is present, or if it
stays in silence mode continuously, it should be
replaced immediately .

17
Protecting Your Family From Fire
Putting up smoke alarms is just one step in
protecting your family from fires. You must also
reduce the chance a fire will start in your dwelling,
and have a plan for escaping safely if one does. To
have a good fire safety program, you must:
Develop a family escape plan and practice it with
everyone in your family, including small children.
1) Draw a floor plan of your residence and identify at
least two exits from each room and one way to get
out of each bedroom without opening the door; 2)
Decide on a meeting place a safe distance from
residence, and make sure everyone knows to wait
there; 3) Know where to go to call the Fire
Department from outside the residence; 4) Make
sure everyone—including all children—know what
the alarm signal means and how to react to it. Teach
them they must be prepared to leave the residence
by themselves if needed; 5) Hold fire drills every 6
months and practice how to escape safely. Show
children how to check if doors are hot before
opening them. Show them how to use an alternate
exit if a door is hot and shouldn’t be opened. Teach
them to stay close to the floor and crawl if
necessary.
Install at least one smoke alarm on every level of
your dwelling and/or dwelling unit, in every bedroom,
and in every sleeping area. Keep alarms clean, and
test them weekly. Replace smoke alarms
immediately if they are not working properly. Smoke
alarms that do not work cannot alert you
to a fire.
Keep at least one working fire extinguisher on every
floor, and an additional one in the kitchen. Have fire
escape ladders or other reliable means of escape
from an upper floor in case stairs are blocked.
Follow safety rules, and prevent hazardous
situations: 1) Use smoking materials properly. Never
smoke in bed. 2) Keep matches or lighters away
from children; 3) Store flammable materials in proper
containers; 4) Keep electrical appliances in good
condition and don’t overload electrical circuits; 5)
Keep stoves, barbecue grills, fireplaces and
chimneys free from grease and debris; 6) Never
leave anything cooking on the stove unattended; 7)
Keep portable heaters and open flames, like
candles, away from flammable materials; 8) Don’t
allow rubbish to accumulate.

18
What To Do
In Case Of Fire
• Don’t panic; stay calm. Follow your escape
plan.Yoursafe escapemay depend onthinking
clearly and remembering what you have prac-
ticed.
• Get out of the dwelling as quickly as possible.
Don’t stop to get dressed or collect anything.
• Feel doors with the back of your hand before
opening them to see if they are hot. If a door is
cool, open it slowly. Don’t open a hot door—
use an alternate escape route.
• Cover your nose and mouth with a cloth (pref-
erably wet). Take short, shallow breaths.
• Keep doors and windows closed, unless you
need to escape through them.
• Meet at your planned meeting place outside
your home, and do a head count to make sure
everyone got out safely.
• Call the Fire Department as soon as possible
from outside. Give your address, then your
name.
• Never go back inside a burning building for any
reason.
Contact your Fire Department for more ideas on
making your home safer, and on creating your own
family escape plan.
If Your Smoke Alarm
Needs Service
CAUTION!
Always discharge the branch circuit before servicing
an AC or AC/DC smoke alarm. First, turn off the AC
power at the circuit breaker or fuse box. Next,
remove the battery from smoke alarms with battery
back-up. Finally, press and hold the test button for 5-
10 seconds to discharge the branch circuit.
If this unit is not working properly, there are a few
simple things you should check before returning or
replacing the unit.
• Make sure it is clean as described in ”Regular
Maintenance.” A build-up of dirt, dust or
grease can affect the units performance.
• Make sure the unit is installed in a proper loca-
tion. If you experience frequent unwanted
alarms, try relocating it. See “Where To Install
Smoke Alarms” for details.
• Make sure it is receiving AC power from the
household current. Check that the back-up
battery is fresh and still providing back-up
protection.
If the unit is still not operating properly, and it is
still under warranty, send it, shipping prepaid to:
BRK Brands, Inc., Attn: Consumer Affairs, 3920
Enterprise Court, Aurora, IL 60504-8132. Enclose a
note in the package describing what’s wrong with
the unit. See warranty information at the end of this
manual.
CAUTION!
Do not try to fix the unit yourself—this will void your
warranty!