User's Manual

2
DESIGN CONSIDERATIONS
The system design and installation must follow accepted
principles of fire protection engineering, as well as comply
with applicable codes and standards:
• NFPA-72, National Fire Alarm Code
• NEC 760, National Electric Code
• Any local installation requirements
• Requirements of the Authority Having Jurisdiction
(AHJ)
1. Selection of the appropriate part number for a specific
application must take into consideration the tempera-
ture of the hazard, the ambient temperature, and the
environment where the sensor is installed.
2. For open area protection, LHS must be mounted at the
ceiling, using the FM Approved spacing between paral-
lel runs. Distances from walls are half the spacing
shown. The thermal path to the LHS sensor must not
be obstructed. Maintain a 1” (25 mm) distance from the
ceiling for fastest detection.
3. For proximity detection, the LHS sensor must be tight
against the object being protected, to insure good ther-
mal transfer. Exercise care to insure that vibration and
sharp edges do not cause abrasions to the cable, which
could result in a false activation.
4. Outdoor applications may need to be shielded from di-
rect sunlight to prevent the LHS sensor’s operating tem-
perature and/or maximum ambient temperature from
being exceeded, which may cause a false activation.
5. To use LHS sensor in hazardous locations (Class 1
Groups A,B,C,D; and Class 2 Groups E,F,G), FM Ap-
proved intrinsic safety barriers must be used to isolate
the sensor from the control panel.
INITIATING CIRCUIT WIRING
The LHS sensor connects to any Fire Control Panel (FCP)
as a dry-contact initiating device. Follow the installation in-
structions of the FCP for specific electrical requirements of
the initiating circuit (see figure 2).
1. The LHS sensor can be run as a Class B or Class A
circuit loop, with no T-taps.
2. The maximum LHS sensor zone length is determined
by the electrical characteristics of the FCP initiating cir-
cuit. Use the LHS resistance and capacitance as shown
in Table 1 to calculate the maximum length. For ex-
ample, a FCP with input loop resistance of 50 ohms will
allow 820 feet (=50/(2 x 0.03048)) of LHS sensor.
3. If the FCP is some distance away from the protected
space, install LHS sensor only in the protected space,
and use lead-in cable to connect the LHS sensor to the
FCP. The lead-in cable can be any copper wiring ap-
proved for fire alarm use.
4. The LHS sensor in the protected space does not need
to be contiguous. Copper wiring approved for fire alarm
use may be used to connect the separate lengths of
LHS sensor.
5. If the initiating circuit is run as Class B (2 wire), then an
end-of-line device compatible with the FCP must be
installed at the end of the LHS sensor cable.
6. If allowed by the AHJ, other initiating devices (smoke
detectors, manual stations, etc.) may be installed on
the same zone as the LHS sensor. The LHS sensor
cable can be wired directly between these other devices.
Initiating
Circuit
Fire
Control
Panel
Junction
Box
LHS Sensor
Cable
Junction
Box
End-of-Line
Device
Lead-In
Cable
Figure 2. FCP with LHS Sensor Cable
SENSOR CABLE MOUNTING
The LHS sensor cable must be mounted in a professional
manner, in accordance with any applicable codes and re-
quirements. The recommended mounting techniques de-
scribed below do not preclude the use of alternate means
that are more suitable for a specific installation so long as
such means are acceptable to the local AHJ.
CAUTION
!
Where subject to mechanical damage, the
sensor cable should be protected to prevent
damage which could result in false activation.
> When designing the LHS layout, sensor cables
should be located where they will not be subject
to physical damage.
> If metal fasteners are used, non-metallic
bushings must be used to prevent chafing or
crushing of the sensor cables.
1. The cable should be adequately supported to prevent
sagging. It is not necessary to tension the cable, how-
ever on straight runs it is recommended that the cable
is supported every 3 feet (1 m). Reduced spacing may
be employed to suit local codes or conditions such as
around corners and transition points. Tension on the
sensor cable cannot exceed 50 Newtons. The sensor
cable can be bent around a radius no smaller than 2”
(50 mm)
2. Wherever possible, the sensor cable should be installed
in a continuous run with as few splices as possible.
3. The sensor cable should be the last item installed on a
project. If not installed last, it should be temporarily sup-
ported by cable ties to minimize the risk of damage.
Care should be taken to prevent damage due to foot
traffic, mechanical impact, kinking or any external heat
sources.