Carrier 48NLT - Manual (Page 8)

3. Use flexible transition between rigid ductwork and unit
to prevent transmission of vibration. The transition may
be screwed or bolted to duct flanges. Use suitable gas­
kets to ensure weather- and airtight seal.
4. Install external, field-supplied air filter(s) in return-air
ductwork where it is easily accessible for service. Rec­
ommended filter sizes are shown in Table 1,
5. Size all ductwork for maximum required airflow (either
heating or cooling) for unit being installed. Avoid abrupt
duct size increases or decreases.
6. Adequately insulate and weatherproof all ductwork lo­
cated outdoors. Insulate ducts passing through uncondi­
tioned space, and use vapor barrier in accordance with
latest issue of SMACNA (Sheet Metal and Air Condi­
tioning Contractors National Association) and ACCA (Air
Conditioning Contractors of America) minimum instal­
lation standards for heating and air conditioning sys­
tems. Secure all ducts to building structure,
7. Flash, weatherproof and vibration-isolate all openings
in building structure in accordance with local codes and
good building practices.
Step 9 — Install Electrical Connections
A WARNING
The unit cabinet must have an uninterrupted, unbroken
electrical ground to minimize the possibility of per­
sonal injury if an electrical fault should occur. This ground
may consist of an electrical wire connected to the unit
ground lug in the control compartment, or conduit ap­
proved for electrical ground when installed in accor­
dance with NEC (National Electrical Code) ANSI/
NFPA (latest edition) (in Canada, Canadian Electrical
Code CSA C22.1) and local electrical codes.
Do not
use gas piping as an electrical ground. Failure to ad­
here to this warning could result in personal injury or
death.
A CAUTION
Failure to follow these precautions could result in dam­
age to the unit being installed:
1. Make all electrical connections in accordance with NEC
ANSI/NFPA (latest edition) and local electrical codes
governing such wiring. In Canada, all electrical connec­
tions must be in accordance with CSA Standard C22.1
Canadian Electrical Code Part 1 and applicable local codes.
Refer to unit wiring diagram.
2. Use only copper conductor for connections between field-
supplied electrical disconnect switch and unit. DO NOT
USE ALUMINUM WIRE.
3. Be sure that high-voltage power to unit is within oper­
ating 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 im­
proper voltage and/or phase balance.
4. Insulate low-voltage wires for highest voltage contained
within conduit when low-voltage control wires are run
in same conduit as high-voltage wires.
5. Do not damage internal components when drilling through
any panel to mount electrical hardware, conduit, etc.
HIGH-VOLTAGE CONNECTIONS - The unit must have
a separate electrical service with a field-supplied, water­
proof, fused disconnect switch mounted at, or within sight
from, the unit. Refer to the unit rating plate for maximum
fuse/circuit breaker size and minimum circuit amps (ampac­
ity) for wire sizing. See Table 3 for electrical data.
The field-supplied disconnect switch box may be mounted
on the unit over the high-voltage inlet hole in the control
corner panel. See Fig. 2 and 3.
Proceed as follows to complete the high-voltage connec­
tions to the unit;
1. Connect ground lead to chassis ground connection when
using separate ground wire.
2. Run high-voltage leads into unit control box and con­
nect to contactor. See unit wiring label, and Fig. 9.
A CAUTION
TRANSFORMER CONTAINS AUTO
RESET OVERCURRENT PROTECTOR.
IT MAY RESET WITHOUT WARNING
STARTING HEATING OR COOLING
SECTION OF THIS PRODUCT.
DISCONNECT POWER PRIOR TO
SERVICING.
THIS COMPARTMENT MUST BE
CLOSED EXCEPT WHEN SERVICING.
316056-201 REV A
Fig. 9 — Transformer Label