Carrier WeatherMaster 48HC14 Installation Instructions Manual page 18

ELECTRIC
DISCONNECT
SWITCH
WIRE ONLY
Fig. 31 — Disconnect Switch and Unit
ALL UNITS — All field wiring must comply with NEC and
all local requirements.
Size wire based on MCA (Minimum Circuit Amps) on the
unit informative plate. See Fig. 32 and the unit label diagram
for power wiring connections to the unit power terminal blocks
and equipment ground. Refer to Table 6 for maximum wire
size at connection lugs.
Provide a ground-fault and short-circuit over-current protec-
tion device (fuse or breaker) per NEC Article 440 (or local
codes). Refer to unit informative data plate for MOCP (Maxi-
mum Over-current Protection) device size.
NOTE: Units ordered with factory installed HACR do not
need an additional ground-fault and short-circuit over-current
protection device unless local codes require.
Voltage to compressor terminals during operation must be
within voltage range indicated on unit nameplate. On 3-phase
units, voltages between phases must be balanced within 2%
and the current within 10%. Use the formula below to deter-
mine the percent of voltage imbalance.
IMPORTANT: Never operate a motor where a phase
imbalance in supply voltage is greater than 2%. Use the
following formula to determine the percentage of volt-
age imbalance:
% Voltage Imbalance:
max voltage deviation from average voltage
= 100 x
average voltage
Example: Supply voltage is 230-3-60.
AB = 224 v
BC = 231 v
AC = 226 v
COPPER
ALUMINUM
WIRE
Average Voltage =
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.
% Voltage Imbalance= 100 x
= 1.76%
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
IMPORTANT: If the supply voltage phase imbalance
is more than 2%, contact your local electric utility
company immediately.
All units except 208/230-v units are factory wired for the
voltage shown on the nameplate. If the 208/230-v unit is to be
connected to a 208-v power supply, the control transformer
must be rewired by moving the black wire with the
male spade connector from the 230-v connection and moving it
to the 200-v 1 / -in. male terminal on the primary side of the
4
transformer. Refer to unit label diagram for additional informa-
tion.
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Operation on improper line voltage or excessive phase
imbalance constitutes abuse and may cause damage to
electrical components. Such operation would invalidate
any applicable Carrier warranty.
NOTE: Check all factory and field electrical connections for
tightness.
UNITS WITHOUT
FUSED DISCONNECT
BREAKER — When installing units, provide a disconnect
switch of adequate size per NEC (National Electrical Code).
Disconnect sizing data is provided on the unit informative
plate. Locate on unit cabinet or within sight of the unit per na-
tional or local codes. Do not cover unit informative plate if
mounting the disconnect on the unit cabinet.
18
224 + 231 + 226
3
681
=
3
= 227
4
226
1
CAUTION
FACTORY-INSTALLED
OR HACR CIRCUIT
/ -in. fe-
4
NON-