17
Fig. 27 — NFD Enclosure Location
Fig. 28 — NFD Handle and Shaft Assembly
UNITS WITHOUT FACTORY-INSTALLED NON-FUSED
DISCONNECT
When installing units, provide a disconnect switch per NEC
(National Electrical Code) of adequate size. Disconnect sizing
data is provided on the unit informative plate. Locate on unit
cabinet or within sight of the unit per national or local codes.
Do not cover unit informative plate if mounting the disconnect
on the unit cabinet.
ALL UNITS
All field wiring must comply with NEC and all local codes.
Size wire based on MCA (Minimum Circuit Amps) on the unit
informative plate. See Fig. 25 and the unit label diagram for
power wiring connections to the unit power terminal blocks
and equipment ground. Maximum wire size is #2ga AWG
(copper only) per pole on contactors. See Fig. 25 and unit label
diagram for field power wiring connections.
Provide a ground fault and short circuit over-current protection
device (fuse or breaker) per NEC Article 440 (or local codes).
Refer to unit informative data plate for MOCP (Maximum
Over-Current Protection) device size.
All units except 208/230v units are factory wired for the volt-
age shown on the nameplate.
If the 208/230v unit is to be con-
nected to a 208v power supply, the control transformer must be
rewired by moving the black wire with the
1
/
4
-in. female spade
connector from the 230v connection and moving it to the 200v
1
/
4
-in. male terminal on the primary side of the transformer.
Refer to unit label diagram for additional information. Field
power wires will be connected at line-side pressure lugs on the
power terminal block or at factory-installed option non-fused
disconnect.
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 shown in the ex-
ample below to determine the percent of voltage imbalance.
Operation on improper line voltage or excessive phase imbal-
ance constitutes abuse and may cause damage to electrical
components. Such operation would invalidate any applicable
Carrier warranty.
% 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 SATISFAC-
TORY AS IT IS BELOW THE MAXIMUM ALLOWABLE
2%.
NOTE: CHECK ALL FACTORY AND FIELD ELECTRI-
CAL CONNECTIONS FOR TIGHTNESS.
CONVENIENCE OUTLETS
Two types of convenience outlets are offered on 48FC models:
non-powered and unit-powered. Both types provide a 125-volt
= 100 x
max voltage deviation from average voltage
average voltage
AB = 224 v
BC = 231 v
AC = 226 v
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.
WARNING
ELECTRICAL OPERATION HAZARD
Failure to follow this warning could result in personal inju-
ry or death.
Units with convenience outlet circuits may use multiple
disconnects. Check convenience outlet for power status
before opening unit for service. Locate its disconnect
switch, if appropriate, and open it. Lock-out and tag-out
this switch, if necessary.
A
B
C
MOTOR