8 Conventional Products—2412AT, 2424AT, and 2424AIT Direct 4-Wire Smoke Detectors
NFPA-72-National Fire Alarm Code defines the spacing requirements for
smoke detectors. Typically, this is a maximum of 30 feet when the
detectors are installed on a smooth ceiling. However, all installations must
comply NFPA-72-National Fire Alarm Code and/or special requirements
of the authority having jurisdiction.
All wiring must be in compliance with the National Electrical Code, the
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 prevent wiring mistakes. Improper connections
can prevent a system from responding properly in the event of a fire.
For IDC wiring (the wiring between interconnected detectors as well as
the control panel), it is recommended that the wire be no smaller than
No. 18 American Wire Gauge (AWG) (1.0 square mm). However, the
screws and clamping plate in the base can accommodate wire sizes up to
No. 12 AWG (3.3 square mm).
For best system performance, the power (+) and (–) wires should be a
twisted pair and installed in a separate grounded conduit or shielded cable
to protect the IDC from extraneous electrical interference. If a cable shield
is provided, the shield connection to and from the detector must be
continuous by using wire nuts, crimping, or soldering as appropriate for a
reliable connection.
To make wire connections:
1.
Strip about 3/8 inch of insulation from the end of the wire (use strip
gauge molded in base).
2.
Slide the bare end of the wire under the clamping plate.
3.
Tighten the clamping plate screw.
Note: Do not loop the wire under the clamping plate.
Figure 3: Class A or Class B Wiring Diagram for 2412AT and
2424AT Detectors used with 4-Wire Control Panels
Spacing
Wiring
Installation
Guidelines
2
7 8
2
1
3
7 8
sm kw ire 5
C la ss A R e tu rn L o o p
E O L P o w e r
S u p e rvisio n
R e la y M o du le
S u g g e sted
E O L
R e sisto r
R e m o te
A n nu n ciato r
1
3
P o w e r to
D e te cto rs
U L Listed
C o n tro l
P a n el
Initia tin g
L o o p
(ID C )
