Assembly - Honeywell 7800 Series Manual

RM7885A
WIRING • ASSEMBLY
5. Recommended grounding practices:
a. Use the earth ground to provide a connection be-
tween the subbase and the control panel or 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
RM7885A requires a low impedance ground con-
nection to the equipment frame which, in turn,
requires a low impedance connection to earth
ground. For a ground path to be low impedance at
RF frequencies, the connection must be made with
minimum length conductors that have a maximum
surface area. Wide straps or brackets are preferred
rather than leadwires. Be careful to verify that
mechanically tightened joints along the ground
path, such as pipe or conduit threads or surfaces
held together with fasteners, are free of nonconduc-
tive coatings and have protected against corrosion
on mating surfaces.
b. Ground the earth ground terminal for each
RM7885A 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
(20A). A number 14 copper conductor is adequate
but wide straps or brackets are preferred rather than
leadwires.
6. Recommended wire routing for flame detector
MOUNTING RM7885A
NOTE: For installation dimensions, see Fig. 1 or 2.
RELAY MODULE MOUNTING
1. Mount the RM7885A vertically, see Fig. 12 or 13 or
mount horizontally with the knife blade terminals pointing
downward. When mounted on the Q7800A, the RM7885A
must be in an electrical enclosure.
2. Select the location in the electrical enclosure. Be sure
to allow adequate clearance for servicing, installation and
removal of the RM7885A, Dust Cover, flame amplifier,
flame amplifier signal voltage probes, electrical signal volt-
age probes and electrical connections.
a. Allow an additional two inches below the RM7885A
for the flame amplifier mounting.
b. Allow an optional three inches minimum to both sides
of the RM7885A for electrical signal voltage probes.
3. Make sure no subbase wiring is projecting beyond the
terminal blocks. Tuck wiring in against the back of the
subbase so it does not interfere with the knife blade terminals
or bifurcated contacts.
4. Mount the RM7885A by aligning the four L shaped
corner guides and knife blade terminals with the bifurcated
contacts on the wiring subbase and tightening the two screws
securely without deforming the plastic.
IMPORTANT: Use plug in action to install the RM7885
rather than hinge action.
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 a conduit with line
voltage circuits.
3. Enclose scanner wires without armor cable in metal
cable or conduit.
4. Follow directions given in the flame detector In-
structions.
7. Maximum wire lengths:
a. For the RM7885A, the maximum length of
leadwire to the terminal inputs (Control) is 300 feet.
b. For the Flame Detector leadwires, the maximum
flame sensor leadwire length is limited by the flame
signal strength.
8. Make sure loads do not exceed the terminal ratings.
Refer to the label on the RM7885A or to the ratings of the
applicable Specification, see Table 1.
9. Check the power supply circuit. The voltage and
frequency tolerance must match those of the RM7885A. Do
not connect the RM7885A to a power supply circuit that can
have line voltage variations, such as on-off switching of
heavy loads. A separate power supply circuit may be required
for the RM7885A with the required disconnect means and
overload protection added.
10. Check all wiring circuits and complete Static Check-
out, Table 4, before installing the RM7885A on the subbase.
11. Install all electrical connectors.
12. Restore power to the panel.
Fig. 12—Electrical panel installation.
16

Assembly