CB780E/CB784E RELAY MODULES WITH VALVE PROVING
32-00150—03
12
750-234
minimum) resistor termination across terminals
1 and 2 of the electrical connectors, for connec-
tions over 100 feet, see Fig. 11–13.
f.
Use the recommended wire size for the 13 Vdc
full wave rectified transformer power input of no.
18 AWG wire insulated for voltages and tempera-
tures encountered in the application. Suggested
wire types include TTW(60C), THW(75C) and
THHN(90C).
5.
Recommended grounding practices:
a. The earth ground provides for a connection
between the subbase and the control panel of
the equipment. The earth ground wire must be
capable of conducting the current to blow the
20A fuse (or breaker) in event of an internal short
circuit. The CB780E/CB784E needs a low
impedance ground connection to the equipment
frame which, in turn, needs a low impedance
connection to earth ground. For a ground path to
be low impedance at RF frequencies, the connec-
tion must be made with minimum length con-
ductors that have a maximum surface area. Wide
straps or brackets are preferred rather than lead-
wires. Be careful to ensure that mechanically
tightened joints along the ground path, such as
pipe or conduit threads or surfaces held together
with fasteners, are free of nonconductive coat-
ings and are protected against corrosion on mat-
ing surfaces.
b. Keyboard Display Module, DATA CONTROL-BUS
MODULE™ or Communication Interface Control-
Bus Module—The shield, if used, should be con-
nected to the signal ground terminal 3(c)
provided as part of the CB780E/CB784E device
ControlBus connection. Connect the shield at
both ends to earth ground.
c. CB780E/CB784E—Each CB780E/CB784E will
have an earth ground terminal that must be
grounded to the metal control panel with wire as
short as practical. Each ground wire must be
capable of carrying a fault current equal to the
rating of the protective fuse (15A maximum, Type
SC or equivalent). A number 14 copper conduc-
tor is adequate, but wide straps or brackets are
preferred rather than leadwires.
6.
Recommended wire routing:
a. Flame detector leadwires:
(1) Do not run high voltage ignition transformer
wires in the same conduit with the flame
detection wiring.
(2) Do not route scanner wires in conduit with
line voltage circuits.
(3) Enclose scanner wires without armor cable in
metal cable or conduit.
(4) Follow directions in flame detector Instruc-
tions.
b. DATA CONTROLBUS MODULE™:
(1) Do not run high voltage ignition transformer
wires in the same conduit or close proximity
with the DATA CONTROLBUS MODULE™ wir-
ing.
(2) Do not route DATA CONTROLBUS MODULE™
wires in conduit with line voltage circuits.
c. Keyboard Display Module (VFD): Because the
VFD is powered from a low voltage, energy lim-
ited source, it can be mounted outside of a con-
trol panel if it is protected from mechanical
damage.
d. Remote Reset:
(1) Do not run high voltage ignition transformer
wires in the same conduit with the Remote
Reset wiring.
(2) Do not route Remote Reset wires in conduit
with line voltage circuits.
NOTE:
A 13 Vdc power supply must be used any time
more than one Keyboard Display Module is used.
7.
Maximum wire lengths:
a. CB780E/CB784E leadwires—The maximum
length of leadwire is 300 feet to terminal inputs
(Control, Preignition Interlock, Running/Lock-
out Interlock, High Fire 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 to a Remote Reset pushbut-
ton.
d. DATA CONTROLBUS MODULE™—The maximum
DATA CONTROLBUS MODULE™ cable length
depends on the number of system modules con-
nected, the noise conditions and the cable used.
The maximum length of all interconnecting wire
is 1000 feet.
8.
Make sure loads do not exceed the terminal ratings.
Refer to the label on the CB780E/CB784E or to the
ratings in Specifications; see Table 1.
9.
Check the power supply circuit. The voltage and fre-
quency tolerance must match those of the
CB780E/CB784E. A separate power supply circuit
may be required for the CB780E/CB784E. Add the
required disconnect means and overload protection.
10.
Check all wiring circuits and complete the Static
Checkout, see Table 8, before installing the
CB780E/CB784E on the subbase.
11.
Install all electrical connectors.
12.
Restore power to the panel.
