Honeywell 7800 Series Manual page 12

RM7840E,G,L,M
WIRING
5. Recommended grounding practices:
a. Use the earth ground to provide a connection
between the subbase and the control panel or the
equipment. The earth ground wire must be ca-
pable of conducting the current to blow the
20A fuse (or breaker) in event of an internal
short circuit. The RM7840 needs a low imped-
ance ground connection to the equipment frame
which, in turn, needs a low impedance connec-
tion 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.
Fig. 7—Wiring RM7840E.
120V ALARM
BURNER MOTOR
(BLOWER)
BURNER
CONTROLLER/LIMITS
LOCKOUT INTERLOCKS
(INC. AIR FLOW SWITCH)
10 SEC. INTERRUPTED
PILOT/IGNITION
MAIN FUEL
VALVE(S)
5 SECOND IGNITION
(EARLY SPARK
TERMINATION)
RECTIFYING FLAME
ROD, RECTIFYING
PHOTOCELL, OR INFRA-
RED (LEAD SULFIDE)
FLAME DETECTOR
OR
C7027A, C7035A, OR
BLUE
WHITE
C7044A ULTRAVIOLET
FLAME DETECTOR
OR
C7012A,C,E,F OR
YELLOW
BLUE
C7076A,D ULTRAVIOLET
FLAME DETECTOR
WHITE
WHITE
BLACK
BLACK
1 120V, 60 Hz POWER SUPPLY. PROVIDE DISCONNECT MEANS AND OVERLOAD PROTECTION AS REQUIRED.
2 DO NOT WIRE TO ANY UNUSED TERMINALS.
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 coatings and
are protected against mating surface corrosion.
b. Each RM7840 has 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 (20A). A number 14
copper conductor is adequate but wide straps or
brackets are preferred rather than leadwires.
6. Recommended wire routing:
a. Flame detector leadwires:
SERIES 90
FIRING RATE
Q7800 MOTOR
HIGH FIRE
G 1 B
2
COMMON
L 1 R
2 3
LOW FIRE
1 W
3
4
MODULATE
4 (L1
1
)
5
5
1
6
6
1
7
LOW FIRE
7
1
START SWITCH
8
HIGH FIRE
8
1
PURGE SWITCH
9
PREIGNITION
2
9
INTERLOCK
0
15 SECOND
1
2
INTERRUPTED
0
1
PILOT VALVE
F
2
2
MASTER
SWITCH
FOR DIRECT SPARK IGNITION (OIL
OR GAS)
1
0
8
9
L2
L1
L2
12
SERIES 90
CONTROLLER
B
R
W
2
L1
(HOT)
1
L2
IGNITION
TRANSFORMER
L
2
MAIN VALVE
M1977A