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912SD: Installation, Start-up, Operating and Service and Maintenance Instructions
are secured to the bracket grounding screw. If the J-Box cover is not
used, the field and factory spliced connections must be located inside the
external electrical box. Do not leave splice connections unprotected
inside the furnace.
Fig. 35 – Installing J-Box (When Used)
The J-Box cover, mounting bracket and screws are shipped in the loose
parts bag included with the furnace. See
locations.
The J-Box mounting bracket and green ground screw is used as a
grounding point for all line voltage wiring options. The J-Box cover may
be omitted when electrical connections are made inside an external
electrical box mounted external to the casing.
External Electrical Box on Furnace Casing
NOTE: Check to ensure that external electrical box does not interfere
with duct work, gas piping or the indoor coil drain. See
alternate electric entry through top panel.
1. Select and remove 7/8-in. (22 mm) knock-out on the desired side of
the casing. Remove the knock-out from the casing.
NOTE: If electrical entry through the furnace top panel is used, a 7/8-in.
(22 mm) hole must be drilled through the top panel.
2. Drill two (2) 1/8-in. (3 mm) pilot holes through the dimples in the
furnace casing near the 7/8-in. knock-out.
Manufacturer reserves the right to change, at any time, specifications and designs without notice and without obligations.
A12226
Fig. 35
for J-Box mounting
Fig. 31
for
26
GROUND
NEUTRAL
LINE VOLTAGE
Fig. 36 – Field-Supplied External Electrical Box on Furnace Casing
NOTE: If electrical entry through the furnace top panel is used, mark
the screw hole locations using the mounting holes in the external
electrical box as a template.
For a side-mounted external electrical box, complete
the following:
1. Align the J-Box bracket with the knock-out inside the furnace
casing.
2. Install the threaded end of a strain-relief bushing through the J-Box
bracket and the furnace casing. Strain-relief bushing should be
installed so that the bushing can be tightened around the wiring
harness inside the furnace casing.
3. Align the external electrical box with the 7/8-in. (22 mm)
knock-out.
4. Install and tighten the lock-nut on the strain-relief bushing inside
the external electrical box.
5. Fasten the external electrical box to the furnace casing using two
(2) sheet metal screws.
6. Route field power wiring into external electrical box.
7. Pull furnace line voltage power wires through strain-relief bushing
of the external electrical box.
8. Pull the ground wire of the field line voltage wiring through the
strain-relief bushing into the furnace casing.
9. Install the green ground screw to the J-Box bracket and attach both
ground wires to the green ground screw.
10. Connect any code required external disconnect(s) to field power
wiring.
11. Connect field power and neutral leads to furnace power leads inside
the external electrical box as shown in
For a top panel-mounted external electrical box,
complete the following:
1. Drill two (2) 1/8-in. (3 mm) pilot holes through the dimples in the
furnace casing near the 7/8-in. knock-out on the side of the casing.
Do not remove the knock-out in the side of the casing.
2. Align the J-Box bracket with the pilot holes inside the furnace
casing.
3. Install 2 screws through the outside of the casing to secure the
J-Box bracket to the furnace casing.
4. Route field power wiring into external electrical box.
5. Pull furnace line voltage power wires through strain-relief bushing
of the external electrical box.
A190278
Fig.
32.
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