System Sensor DH500ACDC - Manual (Page 5)

NOTE: 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 pre-
vent 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-
inch to 1-1/4-inch 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 spec-
ified 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 appropri-
ate 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. Field Wiring
Wiring Installation Guidelines
All wiring must be installed in compliance with the
National Electrical Code and the local codes having juris-
diction, using the proper wire size(s). The conductors used
to connect smoke detectors to control panels and accesso-
ry 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 rec-
ommended that single-conductor wire be no smaller than
18 gauge. The duct detector terminals accommodate wire
sizes up to 14 gauge. The last foot or so of conduit should
be flexible steel conduit (available in electrical supply
houses) which facilitates 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 control panel being used
before wiring the detector loop.
Wiring Instructions
The DH500ACDC is designed for easy wiring. The housing
provides a terminal strip with clamping plates. Wiring con-
nections are made by stripping approximately 3/8-inch of
insulation from the end of the wire, sliding this bare end
under the plate, and tightening the clamping plate screw.
The DH500ACDC is built for 120/240 VAC or 24 VAC/DC to
operate auxiliary functions. See Figure 5A for operating and
wiring details.
Notes on Jumper Wire J5 (See Figure 5A):
1. When the detector is used in a 4-wire application (relay
circuit is being used to control fans, dampers, etc.),
jumper wire J5, located between the two terminal strips
on the printed circuit board, must be cut to insure power
supply supervision.
2. When the detector is used in a 2-wire application (relay
control is not being used for any control of fans,
dampers, etc.), jumper wire J5 must be left in place.
120/240 VAC Operation
To complete the wiring for 110/120 VAC operation, connect
the power supply wires to terminals 15 and 16 (see Figure
5A). If 220/240 VAC operation is preferred, connect the
power supply wires to terminals 16 and 17.
24 VAC/DC Operation
To complete the wiring for 24 VAC or DC, connect the
power supply wires to terminals 7 and 8. Polarity is not
important.
D500-07-00 5 I56-432-11R