System Sensor 1112/24D Installation And Maintenance Instructions Manual

INSTALLATION AND MAINTENANCE INSTRUCTIONS

3825 Ohio Avenue, St. Charles, Illinois 60174

1112/24D Ionization Smoke Detector

1-800-SENSOR2, FAX: [phone]

IMPORTANT: OBSERVE POLARITY

This detector requires that you observe polarity when wiring. If wiring polarity is not observed on the
initiating loop, the unit will send an alarm signal to the control panel to signify incorrect wiring.

Figure 1. Wiring diagram for the 1112/24D detector:

+

POWER

TO

DETECTORS

UL LISTED
CONTROL

PANEL

–

+
+

N.O.

C

–

+

–

+
+

N.O.

C

–

+

–

EOL POWER
SUPERVISION
RELAY (SHOWN
ENERGIZED)
A77-716B 12/24V

EOL RESISTOR
SPECIFIED BY
PANEL
MANUFACTURER

LOOP

+
–

OPTIONAL CLASS A WIRING

NOTE

: Observe polarity in power and initiating loops when wiring.

INITIATING

Before Installing

Please thoroughly read System Sensor Manual I56-407,
Guide for Proper Use of System Smoke Detectors, which
provides detailed information on detector spacing,
placement, zoning, wiring, and special applications.
Copies of this manual are available at no charge from
System Sensor.

NOTICE: This manual should be left with the owner/user
of this equipment.

IMPORTANT: This detector must be tested and maintained
following NFPA 72 requirements. The detector should be
cleaned at least once a year.

General Description

The 1112/24D is a 4-wire ionization smoke detector that
uses a state-of-the-art sensing chamber. This detector is
designed to provide open area protection.

A78-2336-05

Installation of this detector is simplified by the use of an
adapter bracket and a plug-in screw terminal block that
can be prewired to the system, allowing the detector to
be easily installed or removed for cleaning. The detector
sensitivity can be tested in place using the MOD400R
Test Module.

An LED on the detector provides local visual indication of
the detector status. If power is applied to the detector, and
it is functioning normally in standby, the status LED blinks
every five seconds. The LED also latches on in alarm.

The 1112/24D also features visual indication that mainte­nance is required; if the sensing chamber drifts out of its
sensitivity limits, the LED ceases to blink.

D200-63-00 1 I56-931-06

Specifications

Diameter: 5.5 inches (140 mm)
Height (including adapter bracket): 1.7 inches (43 mm)
Weight: 5.3 oz. (150 g)
Operating Temperature Range: 32° to 120° F (0° to 50°C)
Operating Humidity Range: 10% to 93% Relative Humidity, Noncondensing
Latching Alarm: Reset by momentary power interruption
Relay Contact Rating–
Resistive Load: 0.1A @ 35VDC

Electrical Ratings

System Voltage nominal: 12 or 24 VDC; 8.5 VDC minimum; 35 VDC maximum
Maximum Ripple Voltage: 30% of nominal voltage (peak to peak)
Reset Voltage: 0.8 VDC minimum
Standby Current: 50 µA maximum
Alarm Current: 17 mA typical, 23 mA maximum @ 12V; 19 mA typical, 25 mA maximum @ 24V
Reset Time: 0.3 seconds maximum
Start-up Time: 30 seconds maximum (after 60 second reset)

Figure 2. Surface mounting 1112/24D detector on 31/2
inch and 4 inch octagonal box:

A78-2563-00

Figure 3. 1112/24D detector mounting bracket:

TAMPER RESISTANT TAB
(CUT OFF SMALL TAB TO
ACTIVATE TAMPER-RESIST
FEATURE)

ALIGNMENT ARROWS

A78-2333-02

Mounting

Each 1112/24D detector is supplied with a mounting
bracket that permits the detector to be mounted:

pair may be used to provide additional protection against
electrical interference.

1. To a single gang box, or

2. Directly to a 31/2-inch or 4-inch octagonal box, or

3. To a 4-inch square electrical box by using a plaster ring.

Smoke detectors and alarm system control panels have
specifications for allowable loop resistance. Consult the
control panel specifications for the total loop resistance al-

Wiring Installation Guidelines

lowed for the control panel being used before wiring the
detector loops.

CAUTION

Be certain to observe polarity when wiring.

All wiring must be installed in compliance with the Na­tional Electrical Code, applicable local codes, and any spe­cial requirements of the local authority having jurisdiction.
Proper wire gauges should be used. The conductors used to
connect smoke detectors to control panels and accessory
devices should be color-coded to reduce the likelihood of
wiring errors. Improper connections can prevent a system
from responding properly in the event of a fire.

The screw terminal block accepts 14 – 22 gauge wire. For
best system performance, all wiring should be installed in
separate grounded conduit. Do not mix fire system wiring
in the same conduit as any other electrical wiring. Twisted

D200-63-00 2 I56-931-06

Wire connections are made by stripping about 1/4 inch of
insulation from the end of the feed wire, inserting the wire
into the appropriate terminal, and tightening the screw to
secure the wire in place.

Tamper-Resist Feature

This detector includes a tamper-resist feature that prevents
its removal from the bracket without the use of a tool. To
make the detector tamper-resistant, remove the smaller tab
by breaking it at the scribed line on the tamper resistant tab
on the detector mounting bracket (see Figure 3), then in­stall the detector. To remove the detector from the bracket
once it has been made tamper resistant, use a small screw­driver to depress the tamper-resistant tab, located in the