Wiring - Honeywell 7800 SERIES Manual

MOUNTING WIRING SUBBASE
NOTE: For installation dimensions, see Figs. 1 or 2.
1. Mount the subbase in any position except horizontally
with the bifurcated contacts pointing down. The standard
vertical position is recommended. Any other position de-
creases the maximum ambient temperature rating.
2. Select a location on a wall, burner or electrical panel.
1. a. For proper subbase wiring, refer to Fig. 7.
b. For proper remote wiring of the Keyboard Display
Module; refer to the Specifications for the Key-
board Display Module (65-0090), Communi-
cation Interface Base Unit (63-2278), DATA
CONTROLBUS MODULE™ (65-0091) or
Extension Cable Assembly (65-0131).
2. Disconnect the power supply from the main discon-
nect before beginning installation to prevent electrical shock
and equipment damage. More than one disconnect may be
involved.
3. All wiring must comply with all appropriate electrical
codes, ordinances and regulations. Wiring, where required,
must comply with NEC Class 1 (Line Voltage) wiring.
4. Recommended wire size and type: Use no. 14, 16, or
18 copper conductor (TTW60C or THW75C or THHN90C)
600 volt insulation wire for all line voltage terminals. For
high temperature installations, use wire selected for a tem-
perature rating above the maximum operating temperature.
All leadwires must be moisture resistant.
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
RM7890 needs a low impedance ground connec-
tion 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 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 nonconductive coatings and
are protected against mating surface corrosion.
The Q7800 can be mounted directly in the control cabinet. Be
sure to allow adequate clearance for servicing, installation,
access and removal of the RM7890, Dust Cover, flame
amplifier, flame amplifier signal voltage probes, 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. Drill the pilot
holes.
4. Securley mount the subbase using four no. 6 screws.
b. The earth ground terminal for each RM7890 must
be grounded to the metal control panel with wire as
short as practical. Each ground wire must be ca-
pable 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
leadwires:
• Do not run high voltage ignition transformer wires
in the same conduit with the flame detection wiring.
• Do not route scanner wires in a conduit with line
voltage circuits.
• Enclose scanner wires without armor cable in metal
cable or conduit.
• Follow directions given in the flame detector In-
structions.
7. Maximum wire lengths:
a. For the RM7890, the maximum length of leadwire
to the control terminal input 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 RM7890 or to the ratings in the
Specifications, see Table 1.
9. Check the power supply circuit. The voltage and
frequency tolerance must match those of the RM7890. A
separate power supply circuit may be required for the RM7890
with the required disconnect means and overload protection
added.
10. Check all wiring circuits and complete the Static
Checkout, see Table 4, before installing the RM7890 on the
subbase.
11. Install all electrical connectors.
12. Restore power to the panel.
11
RM7890A,B,C
INSTALLATION • WIRING

Wiring

65-0126—2