Field Installed Control Wiring - Trane CAUC-C80 Installation Operation & Maintenance

Power Wire Sizing and Protection Device Equations
To correctly size the main power wiring for the unit, use the appropriate calculation(s) listed below. Read the load definitions
that follow and use Calculation #1 for determining the MCA (Minimum Circuit Ampacity), MOP (Maximum Over current Pro-
tection), and RDE (Recommended Dual Element fuse size) for each unit. Use Calculation #2 to determine the DSS (Discon-
nect Switch Size) for each unit.
Load Definitions: LOAD 1 = CURRENT OF THE LARGEST MOTOR (COMPRESSOR OR FAN MOTOR)
LOAD 2 = SUM OF THE CURRENTS OF ALL REMAINING MOTORS
LOAD 4 = CONTROL POWER TRANSFORMER
Calculation #1
(MCA, MOP, and RDE)
MCA = (1.25 x LOAD 1) + LOAD 2 + LOAD 4
Select a fuse rating equal to the MOP value. If the MOP value does not equal a standard fuse size as listed in NEC 240 - 6,
select the next lower standard fuse rating.
Note: If selected MOP is less than the MCA, then select the lowest standard maximum fuse size which is equal
to or larger than the MCA, provided the selected fuse size does not exceed 800 amps.
Select a fuse rating equal to the RDE value. If the RDE value does not equal a standard fuse size as listed in NEC 240 - 6
select the next higher standard fuse rating.
Note: If the selected RDE is greater than the selected MOP value, then select the RDE value to equal the MOP
value.
Calculation #2
Disconnect Switch Sizing (DSS)

Field Installed Control Wiring

Before installing any connecting wiring, refer to Figure 3-2
for the electrical access locations provided on the unit. In-
stall appropriately sized control wiring for the 115 volt elec-
trical components as required by the application.
H A Z A R D O U S V O LTA G E !
DISCONNECT ALL ELECTRIC POWER INCLUDING
REMOTE DISCONNECTS BEFORE SERVICING.
Failure to disconnect power before servicing can
cause severe personal injury or death.
Since the unit-mounted 115V control power transformer
(1T1) is provided on all units, it is not necessary to run a
separate 115 volt control power source to the unit.
= AND ANY OTHER LOAD RATED AT 1 AMP OR MORE
RDE = (1.5 x LOAD 1) + LOAD 2 + LOAD 4
DSS = 1.15 X (LOAD 1 + LOAD 2 + LOAD 4)
20
Installation (Continued)
MOP = (2.25 x LOAD 1) + LOAD 2 + LOAD 4
Note: 200/230 Volt units are shipped with
transformer 1T1 wired for 200 volt operation. If the
unit is to be operated on a 230 volt power supply,
rewire the transformer as shown on the unit
schematic.
When the 115 volt control circuit is properly connected to
the field provided interlock contacts 6K1 for circuit #1 and
6K2 for circuit #2 (if applicable), proper condenser fan cy-
cling and ambient control for the remaining fans is achieved
with corresponding compressor operation.
Note: All field wiring must conform to NEC
guidelines as well as state and local codes.