RM7895A,B,C,D/EC7895A,C; RM7896A,C,D 7800 SERIES RELAY MODULES
732-00156—01
Table 1. Recommended Wire Sizes and Part Numbers.
aThe KDM, Data ControlBus™ Module (for remote mounting or communications) or Communication Interface Control-
Bus™ Module must be wired in 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 electri-
cal connectors for connections over 100 feet (31 meters).
Table 2. Recommended Grounding Practices.
7. Recommended wire routing of leadwires:
a. Do not run high voltage ignition transformer
wires in the same conduit with the flame
detector, Data ControlBus Module™, or Remote
Reset Module wiring.
b. Do not route flame detector, Data ControlBus™
Module, or Remote Reset Module leadwires in
conduit with line voltage circuits.
c. Enclose flame detector leadwires without armor
cable in metal cable or conduit.
d. Follow directions in flame detector, Data
ControlBus™ Module, or Remote Reset Module
Instructions.
8. The KDM is powered from a low voltage, energy lim-
ited source. It can be mounted outside of a control
panel if it is protected from mechanical damage.
NOTE: A 13 Vdc power supply must be used any time
more than one KDM is used.
9. Maximum wire lengths:
a. RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D
leadwires: The maximum leadwire length is 300
feet to terminal inputs (Control,
Running/Lockout Interlock).
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
pushbutton.
d. Data ControlBus Module™: The maximum Data
ControlBus™ Module cable length depends on
the number of system modules connected, the
noise conditions and the cable used. The
maximum length of all Data ControlBus™
Module interconnecting wire is 4000 feet (1219
meters).
10. Be sure loads do not exceed the terminal ratings.
Refer to the label on the
RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D or to
the terminal ratings in Table 3.
Final Wiring Check
1. Check the power supply circuit. The voltage and
frequency tolerance must match those of the
RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D. A
separate power supply circuit can be required for the
RM7895A,B,C,D/EC7895A,C; RM7896A,B,C,D. Add
the required disconnect means and overload
protection.
2. Check all wiring circuits and complete Static Check-
out in Table 6 before installing the RM7895A,B,C,D/
EC7895A,C; RM7896A,B,C,D on the subbase.
3. Install all electrical connectors.
4. Restore power to the panel.
Application Recommended Wire Size Recommended Part Numbers
Line voltage terminals. 14, 16 or 18 AWG copper conductor, 600 volt insulation,
moisture-resistant wire.
TTW60C, THW75C, THHN90C.
Keyboard Display Module 22 AWG two-wire twisted pair with ground, or five-wire. Belden 8723 shielded cable or
equivalent.
Data ControlBus™
Modulea
22 AWG two-wire twisted pair with ground, or five-wire. Belden 8723 shielded cable or
equivalent.
Remote Reset Module 22 AWG two-wire twisted pair, insulated for low voltage. —
Communications Interface
ControlBus™ Modulea
22 AWG two-wire twisted pair with ground. Belden 8723 shielded cable or
equivalent.
13 Vdc full-wave rectified
transformer power input.
18 AWG wire insulated for voltages and temperatures for
given application.
TTW60C, THW75C, THHN90C.
Ground Type Recommended Practice
Earth ground (subbase and relay
module).
1. Use to provide a connection between the subbase and the control panel of the
equipment. Earth ground must be capable of conducting enough current to
blow the 20A fuse (or breaker) in the event of an internal short circuit.
2. Use wide straps or brackets to provide minimum length, maximum surface area
ground conductors. If a leadwire is required, use 14 AWG copper wire.
3. Make sure that mechanically tightened joints along the ground path are free of
nonconductive coatings and protected against corrosion on mating surfaces.
Signal ground (Keyboard Display
Module, Data ControlBus™ Module,
Communications Interface
ControlBus™ Module.
Use the shield of the signal wire to ground the device to the signal ground terminal
3(c) of each device. Connect the shield at both ends of the daisy chain to earth
ground.
