System Sensor DH400P - Manual (Page 5)

Install the inlet tube as follows:
1. Drill a 3/4-inch hole in the duct directly opposite the
hole already drilled for the inlet tube.
2. Slide the inlet tube with the flange into the centermost
housing bushing. Position the tube so that the arrows
point into the air flow. Secure the tube flange to the
housing bushing with two #6 self-tapping screws.
3. From inside the duct, couple the other section of the in-
let tube to the section already installed using the 1/2-
inch conduit fitting supplied. Make sure that the holes
on both of the air inlet tubes are lined up and facing into
the air flow.
4. Trim the end of the tube protruding through the duct so
that 1 to 2 inches of the tube extend outside the duct.
Plug this end with the end plug and tape closed any
holes in the protruding section of the tube. Be sure to
seal the duct when the tube protrudes.
NOTE: An alternate method to using the ST-10 is to use
two ST-5 inlet tubes. Remove the flange from one
of the tubes and install as described above. After
the installation, use electrical tape to close off
some of the sampling holes so that there are a total
of 10 to 12 holes spaced as evenly as possible
across the width of the duct.
NOTE: Air currents inside the duct may cause excessive
vibration, especially when the longer sampling
tubes are used. In these cases a 3 inch floor flange
(available at most plumbing supply stores) may be
used to fasten the sampling tube to the other side
of the duct. When using the flange/connector
mounting technique, drill a 1 inch to 1-1/4 inch
hole where the flange will be used.
[5.4.3] Modifications of Inlet Sampling Tubes
There may be applications where duct widths are not what
is specified for the installation. In such cases, it is permis-
sible to modify an inlet sampling tube that is longer than
necessary to span the duct width.
Use a 0.193-inch diameter (#11) drill and add the appropri-
ate number of holes so that the total number of holes ex-
posed to the air flow in the duct is 10 to 12. Space the
additional holes as evenly as possible over the length of the
tube.
[5.5] Field Wiring
Wiring Installation Guidelines
All wiring must be installed in compliance with the Na-
tional Electrical Code and the local codes having jurisdic-
tion. Proper wire gauges should be used. The conductors
used to connect smoke detectors to control panels and ac-
cessory 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 signal wiring, (the wiring between interconnected de-
tectors or from detectors to auxiliary devices), it is usually
recommended that single conductor wire be no smaller
than 18 gauge. The duct detector terminals accommodate
wire sizes up to 14 gauge. The last foot of conduit should
be flexible steel conduit (available in electrical supply
houses), which facilitates easier installation and puts less
strain on the conduit holes in the housing. Solid conduit
connections may be used if desired.
Smoke detectors and alarm system control panels have
specifications for allowable loop resistance. Consult the
control panel manufacturer’s specifications for the total
loop resistance allowed for the particular model control
panel being used before wiring the detector loop.
Wiring Instructions
The DH400 detectors are designed for easy wiring. The
housing provides a terminal strip with clamping plates.
Wiring connections are made by stripping about 3/8-inch
of insulation from the end of the wire, sliding the bare end
under the plate, and tightening the clamping plate screw.
DH400 detectors are designed to operate with 12 or 24 VDC
UL listed 2-wire compatible control panels. Alarm current
must be limited by the control panel to 100mA or less. An
example of a UL listed compatible control panel is the Fire-
Lite model Sensiscan 1000 using zone card ANC-2 and
compatibility identification “A”. Install per installation in-
struction S1000/801. A maximum of 20 detectors may be
installed per zone.
D400-14-00 5 I56-554-05