507581-04 Page 41 of 60Issue 2128
Electrical
ELECTROSTATIC DISCHARGE (ESD)
Precautions and Procedures
Electrostatic discharge can affect electronic components.
Take precautions during furnace installation and service
to protect the furnace’s electronic controls. Precautions
will help to avoid control exposure to electrostatic
discharge by putting the furnace, the control and the
technician at the same electrostatic potential. Neutralize
electrostatic charge by touching hand and all tools on
an unpainted unit surface, such as the gas valve or
blower deck, before performing any service procedure.
CAUTION
Figure 63. Interior Make-Up Box Installation
Figure 64. Interior Make-Up Box Installation
The unit is equipped with a eld makeup box. The makeup
box may be moved to the right side of the furnace to
facilitate installation. Seal unused openings on left side
with plugs removed from right side. Secure the excess wire
to the existing harness to protect it from damage.
Refer to Figure 66 for eld wiring diagram and
troubleshooting.
1. The power supply wiring must meet Class I restrictions.
Protected by either a fuse or circuit breaker, select
circuit protection and wire size according to unit
nameplate.
NOTE: Unit nameplate states maximum current draw.
Maximum over current protection allowed is shown in
Table 9.
2. Holes are on both sides of the furnace cabinet to
facilitate wiring.
3. Install a separate (properly sized) disconnect switch
near the furnace so that power can be turned off for
servicing.
Table 9.
Model
Maximum Over-Current
Protection (Amps)
030B08, 045B12, 070B12,
090C12, 090C16, 090C20, 110C16
15
110C20 20
4. Before connecting the thermostat, check to make sure
the wires will be long enough for servicing at a later
date. Make sure that thermostat wire is long enough to
facilitate future removal of blower for service.
5. Complete the wiring connections to the equipment.
Use the provided unit wiring diagram and the eld
wiring diagram shown in Figure 66. Use 18 gauge
wire or larger that is suitable for Class II rating for
thermostat connections.
6. Electrically ground the unit according to local codes or,
in the absence of local codes, according to the current
National Electric Code (ANSI/NFPA No. 70). A green
ground wire is provided in the eld make-up box.
NOTE: This furnace contains electronic components
that are polarity sensitive. Make sure that the furnace
is wired correctly and is properly grounded.
7. One line voltage “ACC” 1/4” spade terminal is provided
on the furnace integrated control. See Figure 65
for integrated control conguration. This terminal is
energized when the indoor blower is operating. Any
accessory rated up to one amp can be connected to
this terminal with the neutral leg of the circuit being
connected to one of the provided neutral terminals.
If an accessory rated at greater than one amp is
connected to this terminal, it is necessary to use an
external relay.
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