25
Do not route control wiring in the same conduit as power wiring.
If disconnect box is mounted to corner post, be careful not to drill
or screw into the condenser coil.
Routing Through Bottom of Unit
If wiring is brought in through bottom of unit, use field-supplied
watertight conduit to route power wiring through the 3
1
/
2
-in.
diameter hole provided in the unit basepan. Install conduit connec
-
tor in unit basepan as shown in Fig. 5-12. Route power and ground
lines through connector to terminal connections in unit control box
as shown on unit wiring diagram and Fig. 23.
Use strain relief going into control box through 3
5
/
8
-in. diameter
hole provided. After wires are in unit control box, connect to
power terminal block. See “POWER WIRING” on page 24.
Low-voltage wiring must be run in watertight conduit from the
basepan to control box and through
7
/
8
-in. diameter hole provided
in bottom of unit control box. Field-supplied strain relief must be
used going into the box. After wiring is in control box, make con
-
nections to proper terminals on terminal blocks (see Field Control
Wiring section).
Routing Through Side of Unit
Route power wiring in field-supplied watertight conduit into unit
through 2
1
/
2
-in. (sizes 020-035) or 3-in. (sizes 040-060) hole.
Use field-supplied strain relief going into control box through
3
5
⁄
8
-in. diameter hole provided. After wires are in unit control
box, connect to power terminal block. See “POWER WIRING”
Bring low-voltage control wiring through the
7
/
8
-in. diameter hole
provided in the condenser section side post. Use strain relief going
into
7
/
8
-in. diameter hole in bottom of unit control box.
After wiring is in control box, make connection to proper termi
-
nals on terminal blocks. See “FIELD CONTROL WIRING” on
this page.
Affix crankcase heater sticker (located in the installer’s packet) to
unit disconnect switch.
Voltage to compressor terminals during compressor operation
must be within the voltage range indicated on the unit nameplate.
Phases must be balanced within 2%.
Use the following formula to determine the percent of voltage
imbalance.
Example: Supply voltage is 230-3-60
Determine maximum deviation from average voltage.
(AB) 227-224 = 3 v
(BC) 231-227 = 4 v
(AC) 227-226 = 1 v
Maximum deviation is 4 v.
Determine percent of voltage imbalance.
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
NOTE: Check all factory and field electrical connections for
tightness.
Unit failure as a result of operation on improper line voltage or ex
-
cessive phase imbalance constitutes abuse and may cause damage
to electrical components.
On 208/230-v units, transformers 1-5 are wired for 230-v. If 208/
230-v unit is to be run with 208-v power supply, the transformers
must be rewired as follows:
For transformer 1 move the black wire connected to terminal H2
and connect it to terminal H3.
For transformers 2-4, used for the 24-volt control circuits, connect
as follows:
1. Remove cap from red (208 v) wire.
2. Remove cap from spliced orange (230 v) wire. Disconnect
orange wire from black unit power wire.
3. Cap orange wire.
4. Splice red wire and black unit power wire. Cap wires.
If the unit is equipped with the optional convenience outlet con
-
nect the yellow wire to H2 on transformer 5.
FIELD CONTROL WIRING
The 48A Series units support a large number of control options
that can impact the field control wiring.
The control options that the unit can provide relate to the follow
-
ing parameters:
• CV (constant volume), VAV (variable air volume), SAV™
(staged air volume), VVT
®
(variable volume variable tem
-
perature) or Carrier TEMP system control operation.
• Standalone with a thermostat (CV) or with a space sensor
(CV and VAV)
• Network application with CCN (Carrier Comfort Net
-
work
®
) or other networks
• Demand controlled ventilation with CO
2
sensor
• Economizer and economizer with changeover control
• Staged gas heat
• Building and duct static pressure control
• Fire shutdown and smoke control
• Diagnostics and monitoring
For constant volume applications a thermostat (T-Stat) or space
temperature sensor (SPT) will be required.
IMPORTANT: The VAV (variable air volume) units use vari
-
able frequency drives, which generate and can radiate radio
frequency energy. If units are not installed and used in accor
-
dance with these instructions, they may cause radio interfer
-
ence. They have been tested and found to comply with limits of
a Class A computing device pursuant to International Standard
in North American EN 61000-2/3, which are designed to pro
-
vide reasonable protection against such interference when op
-
erated in a commercial environment.
WARNING
The unit must be electrically grounded in accordance with
local codes and NEC ANSI/NFPA 70 (National Fire Protec
-
tion Association). Personal injury may result.
% Voltage
Imbalance = 100 x
max voltage deviation from average voltage
average voltage
AB = 224 v
BC = 231 v
AC = 226 v
A
B
C
MOTOR
Average Voltage =
(224 + 231 + 226)
=
681
=
227
3
3
% Voltage Imbalance = 100x
4
= 1.78%
227
IMPORTANT: If the supply voltage phase imbalance is more than 2%,
contact your local electric utility company immediately.
IMPORTANT: BE CERTAIN UNUSED WIRES ARE
CAPPED. Failure to do so may damage the transformers.