Carrier 48KH - Manual (Page 7)

3. Install external, field-supplied air filterfs) in
return-air ductwork where it is easily accessible
for service. Recommended filter sizes are shown
in Table 2.
4. Size all ductwork for maximum required airflow
(either heating or cooling) for unit being installed.
Avoid abrupt duct size increases or decreases.
5. Adequately insulate and weatherproof all duct­
work located outdoors. Insulate ducts passing
thru an unconditioned space, and use a vapor
barrier in accordance with the latest issue of
SMACNA and NESCA minimum installation
standards for heating and air conditioning
systems. Secure all ducts to building structure.
6. Flash, weatherproof and vibration-isolate all
openings in building structure in accordance with
local codes and good building practices.
Step 4 — Make Wiring Connections
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CAUTION: Taabre foidSow these precaaisons
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1. Make all electrical connections m accordance
with National Electrical Code ANSI/NFPA70-
1981 and local electrical codes governing such
wiring.
2. Use only copper conductor for connections
between the field-supplied electrical disconnect
switch and the unit.
Do not use aluminum or
copper-clad aluminum wire.
3. Ensure that high-voltage power to unit is within
operating voltage range indicated on unit rating
plate. On 3-phase units, ensure that phases are
balanced
within 2%. Consult local power
company for correction of improper voltage
and/or phase balance.
4. When low-voltage control wires are run in same
conduit as high-voltage wires, insulate low-
voltage wires for highest voltage contained within
conduit.
5. Do not damage internal components when drill­
ing thru any panel to mount electrical hardware,
conduit, etc.
6. Make sure service conductors used between elec­
trical service panel and field-supplied electrical
disconnect switch do not have a current capacity
less than the copper wire specified, and do not
create a total voltage drop in excess of 2% of rated
voltage of the unit when compressor is operating.
NOTE: When using aluminum conductor from elec­
trical service to disconnect switch (where local codes
permit use of aluminum wire), make connections in
accordance with National Electrical Code. Prepare
all aluminum wire immediately before installation
by brush-scratching the wire, then coating the wire
with a corrosion inhibitor (such as Pentrox A). Be
sure entire connection is completely covered to pre­
vent an electrochemical reaction that will cause con­
nection to fail very quickly. Do not reduce effective
size of wire by cutting off strands to fit wire into a
connector. Always use properly sized connectors.
HIGH-VOLTAGE CONNECTIONS — Unit must
have a separate electrical service with a field-
supplied, waterproof, fused disconnect switch per
NEC mounted near, and within sight from, the unit.
Refer to unit rating plate for maximum fuse size and
minimum circuit amps (ampacity) for wire sizing.
Table 3 shows recommended wire sizes and lengths
based on rating plate data.
The field-supplied disconnect switch box may be
mounted on unit over the high-voltage inlet hole in
control corner panel. See Fig. 4.
WAXi-NING: Fajt No, A7455tl Ek ‘wblch Is
loosoiij bag oi psxis, mastbea^^^xedto
ibe dlsconaect sssf^tcfe box, Tbis label
«DO NOT DISCONNECT ELEC-
TRiCAL POWER TO TjgXS APPLIANCE
WITHOUT FIRST TURNING OFF THE
OASS.OPFLY.”'
Proceed as follows to complete the high-voltage
connections to unit:
1. Connect ground lead to chassis ground connec­
tion when using a separate ground wire.
2. Run high-voltage leads into unit control box and
connect to contactor. See unit wiring label and
Fig. 6 and 8.
NOTE: On 3-phase units, connect third high-voltage
lead to brown high-voltage pigtail lead. See unit
wiring label and Fig. 8.
SPECIAL PROCEDURES FOR 208-V
OPERATION
WARNING: Httko at«« jmief strppiy i,o unit
is sTwiiclied OFF before iaalaag; asy mdug
For operation on 208 vohs, disconnect orange
transformer-primary lead from contactor. See unit
wiring label and Fig. 6. Remove tape and cover from
terminal on end of red transformer-primary lead.
Save cover. Connect red lead to contactor terminal
from which orange lead was disconnected.