58SB0B/58SB1B: Installation, Start–Up, Operating and Service and Maintenance Instructions
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
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3. Remove the desired electrical box hole knockout and position the
hole in the electrical box over the hole in the furnace casing. 
4. Fasten  the  electrical  box  to  casing  by  driving  two  field  supplied
screws from inside electrical box into casing steel. 
A190278
Fig. 27 – Field-Supplied Electrical Box on Furnace Casing
5. Remove and save two screws holding J-Box.
6. Pull furnace power  wires out  of 1/2-in. (12 mm) diameter hole in
J-Box. Do not loosen wires from strain-relief wire-tie on outside of
J-Box.
7. Route furnace  power  wires through  holes  in  casing  and  electrical
box and into electrical box.
8. Pull field power wires into electrical box.
9. Remove cover from furnace J-Box.
10. Route field ground wire through holes in electrical box and casing,
and into furnace J-Box.
11. Reattach furnace J-Box  to furnace casing with screws removed in
Step 4.
12. Secure field ground wire to J-Box green ground screw. 
13. Complete  electrical  box  wiring  and  installation.  Connect  line
voltage  leads  (see  Fig. 24).  Use  best  practices  (NEC  in  U.S.  for
wire bushings, strain relief, etc.)
14. Reinstall  cover  to  J-Box.  Do  not  pinch  wires  between  cover  and
bracket. 
Power Cord Installation in Furnace J-Box
NOTE: Power cords must be able to handle the electrical requirements
listed in Table 6. Refer to power cord manufacturer’s listings.
1. Remove cover from J-Box.
2. Route listed power cord through 7/8-in. (22 mm) diameter hole in
J-Box.
3. Secure power cord to J-Box bracket with a strain relief bushing or a
connector approved for the type of cord used.
4. Secure field ground wire to green ground screw on J-Box bracket.
5. Connect line voltage leads (see Fig. 24).
6. Reinstall  cover  to  J-Box.  Do  not  pinch  wires  between  cover  and
bracket. 
BX Cable Installation in Furnace J-Box 
1. Remove cover from J-Box.
2. Route BX cable into 7/8-inch diameter hole in J-Box. 
3. Secure BX cable to J-Box bracket with connectors approved for the
type of cable used.
4. Secure field ground wire to green ground screw on J-Box bracket.
5. Connect line voltage leads (see Fig. 24).
6. Reinstall  cover  to  J-Box.  Do  not  pinch  wires  between  cover  and
bracket. 
24-V Wiring 
Make  field  24-V  connections  at  the  24-V  terminal  strip  (see  Fig. 20).
Connect terminal Y for proper cooling operation (see Fig. 28). Use only
AWG No. 18, color-coded, copper thermostat 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.
ACCESSORIES
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 115 VAC, 1.0 amps maximum
and are energized during blower motor operation (see Fig. 28).
2. Humidifier (HUM)
Connect  an accessory 24 VAC, 0.5 amp.  maximum humidifier (if
used)  to  the  1/4-in  male  quick-connect  HUM  terminal  and
COM-24V  screw  terminal  on  the  control  board  thermostat  strip.
The  HUM  terminal  is  energized  when  the  pressure  switch  closes
during a call for heat (see Fig. 28).
NOTE:  DO  NOT  connect  furnace  control  HUM  terminal  to  HUM
(humidifier)  terminal  on  Thermidistatt,  Zone  Controller  or  similar
device.  See  Thermidistat,  Zone  Controller,  thermostat,  or  controller
manufacturer’s instructions for proper connection. 
NOTE:  For 24-V & 115-V  EAC or  Humidifier Accessory details, see
Accessory instructions.
A210192
Fig. 28 – Furnace Control