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Final Wiring Check - Honeywell 7800 Series Installation Instructions Manual

Relay modules
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RM7897A1002, RM7897C1000 7800 SERIES RELAY MODULES
Line voltage terminals.
Keyboard Display Module
Data ControlBus™ Module
Remote Reset Module
Communications Interface
ControlBus™ Module
13 Vdc full-wave rectified
transformer power input.
The KDM, Data ControlBus™ Module (for remote mounting or communications) or Communication Interface ControlBus™
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 electrical connectors for connections
over 100 feet (31 meters).
Ground Type
Earth ground (subbase and relay
Signal ground (Keyboard Display
Module, Data ControlBus™ Module,
Communications Interface
ControlBus™ Module.
Maximum wire lengths:
a. RM7897A,C 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
c. Remote Reset leadwires: The maximum length of
wire is 1000 feet (305 meters) to a Remote Reset
push button.
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).
Table 1. Recommended Wire Sizes and Part Numbers.
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. Belden 8723 shielded cable or equivalent.
22 AWG two-wire twisted pair with ground, or five-wire. Belden 8723 shielded cable or equivalent.
22 AWG two-wire twisted pair, insulated for low voltage. —
22 AWG two-wire twisted pair with ground.
18 AWG wire insulated for voltages and temperatures
for given application.
Table 2. Recommended Grounding Practices.
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
15A, type SC,. fast blow 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.
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.
Recommended Practice
10. Be sure loads do not exceed the terminal ratings. Refer
to the label on the RM7897A,C 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
RM7897A,C. A separate power supply circuit can be
required for the RM7897A,C. Add the required
disconnect means and overload protection.
2. Check all wiring circuits and complete Static Checkout
in Table 6 before installing the RM7897A,C on the
3. Install all electrical connectors.
4. Restore power to the panel.
Recommended Part Numbers
Belden 8723 shielded cable or equivalent.

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