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WARNING: In no case should more than 2 air inlet holes be cut off the tube. There must be a minimum of 10 holes in
the tube exposed to the air stream.
B. INSTALLATION FOR DUCTS MORE THAN 8 (2.4 M) FEET WIDE
NOTE: To install inlet tubes in ducts more than 8 feet wide, work must be performed inside the air duct. Sampling of air
in ducts wider than 8 feet is accomplished by using the SSDST-10 inlet sampling tube.
Install the inlet tube as follows:
1. Drill a 3/4-in (19 mm) hole in the duct directly opposite the hole already drilled for the inlet tube.
2. Slide the inlet tube into the bushing located in the center of the duct housing. Position the tube so that the arrows
point into the air flow. Secure the tube flange to the housing bushing with the two #6 self-tapping screws.
3. From inside the duct, couple the other section of the inlet tube to the section already installed using the 1/2-inch con-
duit fitting supplied. Make sure that the holes in both air inlet tubes are lined up facing the direction of air flow.
4. Trim the end of the tube protruding through the duct so that 1 to 2 in (25 to 51 mm) of the tube extends outside the
duct. Plug this end with the tube end plug and tape closed any holes in the protruding section of the tube. Be sure to
seal the duct when the tube protrudes.
5. Any tube (over 3 ft - 91 cm long) that doesn't protrude through the duct (on the side opposite the housing) must be
supported by other means.
NOTES: – An alternate method to using the SSDST-10 is to use two SSDST-5 inlet tubes. Remove the flange from
one of the tubes and install as described above. After the installation, use electrician's tape to close off
some of the sampling holes so that there is a total of 12 holes spaced as evenly as possible across the
width of the duct.
– Air currents inside the duct may cause excessive vibration. This vibration can slowly open the seal
around the tube and permit air to escape. To prevent this from occurring, a 3-inch floor flange, available
at most plumbing supply houses, may be used. This flange/connector mounting technique makes the
initial installation easier because a 1-in to 1-1/4-in (25 to 32 mm) hole may be drilled where the flange/
connector will be used. It is easier to push the inlet tube through the larger hole.
MODIFICATION OF INLET SAMPLING TUBES
There may be situations where duct widths are not as specified for the installation. In such cases, it is permissible 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 appropriate number of holes so that the total number of holes exposed
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.
STEP 5. COMPLETE FIELD WIRING
Wiring Installation Guidelines
All wiring must be installed in compliance with the National Electrical Code and the local codes having jurisdiction using
the proper wire size. 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.
For signal wiring, (the wiring between interconnected detectors or from detectors to auxiliary devices), it is recommend-
ed that single-conductor wire be no smaller than 18 gauge (0.812 sq. mm). The duct detector terminals accommodate
wire sizes up to 14 gauge (2.087 sq mm). The last foot (30 mm) or so of conduit should be flexible steel conduit (avail-
able in electrical supply houses) which facilitates easier installation and puts less strain on the conduit holes in the hous-
ing. Solid conduit connections may be used, if desired.
To insure stable communications, the loop resistance of the communication line must not exceed 40 ohms.
H500-03-00
5
I56-475-09R
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