507281-06
Page 41 of 58
Issue 1724
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 field 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 field 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.
Model
Maximum Over
Current Protection
(Amps)
045B12, 070B12, 090C12, 030B08
090C16, 090C20, 110C16
15
110C20, 135D20
20
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.
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 field
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 field 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.
