Table of Contents
Advertisement
5121817-TIM-A-0515
When installing equipment in a facility with a 3 phase
high-leg delta power supply, care must be taken to
ensure that the high-leg conductor is not attached to
either of the two legs of the (single phase, direct drive)
X13 or ECM motors. Failure to do so can result in the
motor acting erratically or not running at all.
Check for the high leg conductor by checking voltage of
each phase to ground.
Example: A or L1 phase to ground, voltage reading is
120V. B or L2 phase to ground, voltage reading is 195 to
208V. C or L3 phase to ground, voltage reading is 120V.
Therefore B or L2 phase is the high Leg. The high
should always be wired to the center or B or L2 tap.
Note: Check all three phase motors and compressors
for proper rotation after making a change. If it is
necessary to change 3 phase motor rotation, swap A or
L1 and C or L3 only.
14
Power Wiring Detail
Units are factory wired for the voltage shown on the unit
nameplate. Refer to Electrical Data Table 7 to size power
wiring, fuses, and disconnect switch.
Power wiring is brought into the unit through the side of the unit
or the basepan inside the curb.
Thermostat Wiring
The thermostat should be located on an inside wall
approximately 56 inch above the floor where it will not be
subject to drafts, sun exposure or heat from electrical fixtures or
appliances. Follow the manufacturer's instructions enclosed
with thermostat for general installation procedure. Seven (7)
color-coded, insulated wires should be used to connect the
thermostat to the unit. Refer to Table 6 for control wire sizing
and maximum length.
Table 6: Control Wire Sizes
Wire Size
18 AWG
1. From the unit to the thermostat and back to the unit.
Maximum Length
150 Feet
Johnson Controls Unitary Products
1
Advertisement
Table of Contents
