44
Fig. 64 — Disconnect Switch and Unit (Size 16)
FIELD WIRING FOR 50TC 16 UNITS
All field wiring must comply with the NEC and local
requirements.
All units except 208/230-v units are factory wired for the volt-
age shown on the nameplate. If the 208/230-v unit is to be con-
nected to a 208-v power supply, the control transformer must
be rewired by moving the black wire with the
1
/
4
-in. female
spade connector from the 230-v connection and moving it to
the 200-v
1
/
4
-in. male terminal on the primary side of the trans-
former. Refer to unit label diagram for additional information.
Size wire based on MCA (Minimum Circuit Amps) on the unit
informative plate. See Fig. 63 and the unit label diagram for
power wiring connections to the unit power terminal blocks
and equipment ground. Maximum wire size is 2/0 AWG per
pole.
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.
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 following formula to de-
termine the percent of voltage imbalance.
% 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 maxi-
mum allowable 2%.
NOTE: Check all factory and field electrical connections for tightness.
Units Without Factory-Installed Disconnect
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 discon-
nect sizing data 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.
Units with Factory-Installed Disconnect
The factory-installed option disconnect switch is located in a
weatherproof enclosure located under the main control box (see
Fig. 65). The manual switch handle is accessible through an open-
ing in the access panel. Discard the factory test leads (see Fig. 63
on page 43). The factory disconnect is an 80A disconnect.
Field-Install the NFD Shaft and Handle
1. Remove the Control Box access panel. The NFD enclo-
sure is located below the Control Box (see Fig. 65).
2. Remove (3) cap head screws that secure the NFD enclo-
sure front cover — (2) on the face of the cover and (1) on
the left side cover. See Fig. 66.
3. Remove the front cover of the NFD enclosure.
4. Make sure the NFD shipped from the factory is at OFF
position (the arrow on the black handle knob is at OFF).
5. Insert the shaft with the cross pin on the top of the shaft in
the horizontal position. See Fig. 66.
6. Measure from the tip of the shaft to the top surface of the
black pointer; the measurement should be 3.75 to 3.88 in.
(95 to 99 mm).
7. Tighten the locking screw to secure the shaft to the NFD.
8. Turn the handle to the OFF position with red arrow point-
ing at OFF.
9. Install the handle on to the painted cover horizontally with
the red arrow pointing to the left.
10. Secure the handle to the painted cover with (2) screws and
lock washers supplied.
11. Engaging the shaft into the handle socket, re-install (3)
hex screws on the NFD enclosure.
Re-install the unit front panel.
WARNING
FIRE HAZARD
Failure to follow this warning could result in personal inju-
ry, death, or property damage.
Do not connect aluminum wire between disconnect switch
and unit. Use only copper wire.
= 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
33
% Voltage Imbalance = 100x
4
=1.78%
227
COPPER
WIRE ONLY
ELECTRIC
DISCONNECT
SWITCH
ALUMINUM
WIRE
A
B
C
MOTOR
IMPORTANT: If the supply voltage phase imbalance is more than 2%,
contact your local electric utility company immediately.
CAUTION
UNIT DAMAGE HAZARD
Failure to follow this caution may result in equipment
damage.
Operation on improper line voltage or excessive phase im-
balance constitutes abuse and may cause damage to electri-
cal components. Such operation would invalidate any ap-
plicable Carrier warranty.
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