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Mounting Wiring Subbase
See Fig. 1 for the internal block diagrams of the relay
modules.
1. Mount the subbase in any position except horizontally
with the bifurcated contacts pointing down. The stan-
dard vertical position is recommended. Any other posi-
tion decreases the maximum ambient temperature
rating.
2. Select a location on a wall, burner or electrical panel.
The Q7800 can be mounted directly in the control cabi-
net. Be sure to allow adequate clearance for service,
installation, access or removal of the 7800 SERIES
Relay Module, KDM, flame amplifier, flame amplifier sig-
nal voltage probes, Run/Test Switch, electrical signal
voltage probes and electrical field connections.
3. For surface mounting, use the back of the subbase as a
template to mark the four screw locations; then drill the
pilot holes.
4. Securely mount the subbase using four no. 6 screws.
Wiring Subbase
WARNING
Electrical Shock or Equipment Damage Hazard.
Can cause personal injury or equipment and
control damage.Disconnect all power supplies
before beginning installation.
1. For proper subbase wiring, refer to Fig. 2 or 3.
2. For proper remote wiring of the KDM, refer to the Speci-
fications for the KDM (65-0090), S7810M Modbus Mod-
ule (65-0229), Data ControlBus Module™ (65-0091) or
Extension Cable Assembly (65-0131).
3. Disconnect the power supply from the main disconnect
before beginning installation to prevent electrical shock
and equipment damage. More than one disconnect may
be required.
4.
All wiring must comply with all applicable electrical
codes, ordinances and regulations. Where required, wir-
ing must comply with NEC, Class 1 (Line Voltage) wir-
ing.
5. For recommended wire size and type, see Table 1.
6. For recommended grounding practices, see Table 2.
Application
Line Voltage Terminals
a
KDM
Data ControlBus Module™
Modbus™ Module
a
The KDM, Data ControlBus Module™ (for remote mounting or communications) or Modbus™ Module must be wired in a
daisy chain configuration, (1(a)-1(a), 2(b)-2(b), 3(c)-3(c)). The order of interconnection of all the devices listed above is not
important. Be aware that modules on the closest and farthest end of the daisy chain configuration string require a 120 ohm (1/
4 watt minimum) resistor termination across terminals 1 and 2 of the electrical connectors for connections over 100 feet (30.5
meters).
Table 1. Recommended Wire Size
Recommended Wire Size
14, 16, or 18 AWG copper conductor, 600 volt insulation,
moisture-resistant wire
22 AWG two-wire twisted pair with ground, or five-wire.
Remote Reset Module 22 AWG two-wire twisted pair,
insulated for low voltage.
22 AWG two-wire twisted pair with ground.
EC7820A 7800 SERIES RELAY MODULES
7. Use recommended wire routing of lead wires:
a. Do not run high voltage ignition transformer wires in
the same conduit with the flame detector, Data Con-
trolBus Module™, Modbus Module or Remote Reset
Module wiring.
b. Do not route flame detector, Data ControlBus Mod-
ule™, Modbus Module or Remote Reset Module
lead wires in conduit with line voltage circuits.
c. Enclose flame detector lead wires without armor
cable in metal cable or conduit.
d. Follow directions in the flame detector, Data Control-
Bus Module™, Modbus Module or Remote Reset
Module Instructions.
8. KDM wiring: The KDM is powered from a low voltage,
energy limited source so it can be mounted outside of a
control panel if it is protected from mechanical damage.
NOTE: A separate 13 Vdc power supply must be used
any time more than two Data ControlBus Mod-
,
ules
Modbus Modules or KDM are used or are
placed more than 100 feet (30.5 meters) from the
relay module.
9. Maximum wire lengths:
a. 7800 SERIES Relay Module leadwires—The maxi-
mum length of leadwire is 300 feet (91.4 meters) to
terminal inputs (Control, Preignition Interlock, Run-
ning/Lockout Interlock, High Purge Switch and Low
Fire Switch).
b. Flame Detector leadwires—The maximum flame
sensor leadwire length is limited by the flame signal
strength.
c. Remote Reset leadwires—The maximum length of
wire is 1000 feet (305 meters) to a Remote Reset
push-button.
d. Data ControlBus Module and Modbus Module—The
maximum Data ControlBus Module™ or Modbus
Module cable length depends on the number of sys-
tem modules connected, the noise conditions and
the cable used. The maximum length of all intercon-
necting wire is 4000 feet (1219 meters).
10. Make sure loads do not exceed the terminal ratings.
Refer to the label on the 7800 SERIES Relay Module or
to the ratings in Table 3.
3
Recommended Part Numbers
TTW60C, THW75C, THHN90C
Belden 8723 shielded cable or
equivalent.
—
Belden 8723 shielded cable or
equivalent.
66-1091—08
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