29
Fig. 20 — Disconnect Location
Step 10 — Route Field Wiring
Field power wiring is brought into the unit through the back of the
power box near the bottom. Wiring can be brought through the
roof curb through field-supplied watertight connections.
There are two 3
5
/
8
-in. holes for field power wiring in the power
box and a
7
/
8
-in. hole in the side post for 24-v control wiring pro-
vided. Field-supplied couplings must be used when routing wiring
into the control box.
See Fig. 20 for recommended disconnect location.
Step 11 — Make Field Electrical Connections
POWER WIRING
Units are factory-wired for the voltage shown on unit nameplate.
The main terminal block is suitable for use with copper wires only.
Maximum wire size varies according to disconnect size.
NOTE: Conduit used for field wiring must be sealed at the unit
end of the conduit. Failure to do so could cause the conduit to act
as a chimney in cold climates causing warm building air to con-
dense in the power box.
Units without Factory-Installed Disconnect
When installing units, provide a disconnect per NEC (National
Electrical Code) of adequate size (MOCP [maximum overcurrent
protection] of unit is on the informative plate). 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. 21 for power wiring connections to the unit power terminal
block and equipment ground. Maximum wire size is two (2) 500
MCM (maximum wire size) conductors per pole.
Units with Factory-Installed Disconnect
The factory-installed disconnect is an interlocking, door-type. The
disconnect handle locks the door when it is in the ON position.
The disconnect handle must be in the OFF position to open the
control box door. The disconnect is located in the power box be-
hind the power box door for all units. See Fig. 22.
All field wiring must comply with NEC and all local codes. Wire
must be sized based on MCA (minimum circuit amps) on the unit
informative plate. See Fig. 23 for power wiring connections to the
unit disconnect and equipment ground.
Operating Voltage
Operating voltage to the unit must be within the voltage range in-
dicated on the unit nameplate. Voltages between phases must be
balanced within 2%, and the current must be balanced within
10%. See Table 7 for motor limits.
Use the following formula to determine the percentage of voltage
imbalance.
Voltage Imbalance
Example: Supply voltage is 460-3-60.
AB = 452 v
BC = 464 v
AC = 455 v
Determine maximum deviation from average voltage:
(AB) 457 – 452 = 5 v
(BC) 464 – 457 = 7 v
(AC) 457 – 455 = 2 v
Maximum deviation is 7 v.
Determine percent voltage imbalance:
This amount of phase imbalance is satisfactory as it is below the
maximum allowable 2%.
RECOMMENDED
FIELD-SUPPLIED
DISCONNECT
LOCATION
CAUTION
Use care when drilling into corner post to avoid damage to
condenser coil.
IMPORTANT: All units have variable frequency drives (VFD)
factory installed. VFDs generate, use, 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 Stan-
dard EN 61000-2/3, which are designed to provide reasonable
protection against such interference when operated in a com-
mercial environment.
DISCONNECT SIZE QUANTITY...MAXIMUM WIRE SIZE (MCM)
400 Amps
600 Amps
800 Amps
2...500
2...500
2...500
= 100 x
max voltage deviation from average voltage
average voltage
Average Voltage =
452 + 464 + 455
3
=
1371
3
= 457
% Voltage Imbalance = 100 x
7
457
=1.53%
IMPORTANT: If the supply voltage phase imbalance is more
than 2%, contact local utility immediately.
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