36
7. Install the green ground screw to the J−Box bracket and
attach both ground wires to the green ground screw.
8. Connect any code required external disconnect(s) to field
power wiring.
9. Connect field power and neutral leads to furnace power
leads inside the external electrical box as shown in Fig. 34.
Power Cord Installation in Furnace J−Box
NOTE: Power cords must be able to handle the electrical
requirements listed in Table 12. Refer to power cord
manufacturer’s listings.
1. Install J−Box mounting bracket to inside of furnace casing.
See Fig. 36.
2. Route listed power cord through 7/8−in. (22 mm) diameter
hole in casing and J−Box bracket.
3. Secure power cord to J−Box bracket with a strain relief
bushing or a connector approved for the type of cord used.
4. Pull furnace power wires through 1/2−in. (12 mm) diameter
hole in J−Box. If necessary, loosen power wires from
strain—relief wire−tie on furnace wiring harness.
5. Connect field ground wire and factory ground wire to green
ground screw on J−Box mounting bracket as shown in Fig.
36.
6. Connect power cord power and neutral leads to furnace
power leads as shown in Fig. 39.
7. Attach furnace J−Box cover to mounting bracket with
screws supplied in loose parts bag. Do not pinch wires be-
tween cover and bracket. See Fig. 36.
BX Cable Installation in Furnace J−Box
1. Install J−Box mounting bracket to inside of furnace casing.
See Fig. 36.
2. Route BX connector through 7/8−in. (22 mm) diameter
hole in casing and J−Box bracket.
3. Secure BX cable to J−Box bracket with connectors ap-
proved for the type of cable used.
4. Connect field ground wire and factory ground wire to green
ground screw on J−Box mounting bracket as shown in Fig.
36.
5. Connect field power and neutral leads to furnace power
leads. as shown in Fig. 39.
6. Attach furnace J−Box cover to mounting bracket with
screws supplied in loose parts bag. Do not pinch wires be-
tween cover and bracket.
FIRE, EXPLOSION, ELECTRICAL SHOCK, AND
CARBON MONOXIDE POISONING HAZARD
Failure to follow this warning could result in dangerous
operation, personal injury, death, or property damage.
Do not drill into blower shelf of furnace to route control
wiring. Route any control or accessory wiring to the blower
compartment through external knockouts on the casing.
!
WARNING
24−V Wiring
Make field 24−v connections at the 24−v terminal strip. See Fig.
40. Connect terminal Y as shown in Fig. 39 for proper cooling
operation. Use only AWG No. 18, color−coded, copper thermostat
wire.
NOTE: Use AWG No. 18 color-coded copper thermostat wire for
lengths up to 100 ft. (30 M). For wire lengths over 100 ft., use
AWG No. 16 wire.
The 24−v circuit contains an automotive−type, 3−amp. fuse located
on the control. Any direct shorts during installation, service, or
maintenance could cause this fuse to blow. If fuse replacement is
required, use ONLY a 3−amp. fuse of identical size. See Fig. 40.
Accessories (See Fig. 38 and 40.)
1. Electronic Air Cleaner (EAC)
Connect an accessory Electronic Air Cleaner (if used) using
1/4−in. female quick connect terminals to the two male
1/4−in. quick−connect terminals on the control board
marked EAC−1 and EAC−2. The terminals are rated for
115VAC, 1.0 amps maximum and are energized during
blower motor operation.
2. Humidifier (HUM)
The HUM terminal is a 24 VAC output, energized when the LPS
closes during a call for heat.
Connect an accessory 24 VAC, 0.5 amp. maximum humidifier (if
used) to the ¼−in. male quick−connect HUM terminal and
COM−24V screw terminal on the control board thermostat strip.
NOTE: If the humidifier has its own 24 VAC power supply, an
isolation relay may be required. Connect the 24 VAC coil of the
isolation relay to the HUM and COM/24V screw terminal on the
control board thermostat strip. See Fig. 38.
Alternate Power Supplies
This furnace is designed to operate on utility generated power
which has a smooth sinusoidal waveform. If the furnace is to be
operated on a generator or other alternate power supply, the
alternate power supply must produce a smooth sinusoidal
waveform for compatibility with the furnace electronics. The
alternate power supply must generate the same voltage, phase, and
frequency (Hz) as shown in Table 12 or the furnace rating plate.
Power from an alternate power supply that is non-sinusoidal may
damage the furnace electronics or cause erratic operation.
Contact the alternate power supply manufacturer for specifications
and details.
912S
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