JOHNSON CONTROLS
33
SECTION 4: INSTALLATION
FORM 150.73-NM1
ISSUE DATE: 07/03/2024
4
Copper power wiring only should be used for supply-
ing power to the unit. This is recommended to avoid
safety and reliability issues resulting from connection
failure at the power connections to the unit. Aluminum
wiring is not recommended due to thermal character-
istics that may cause loose terminations resulting from
the contraction and expansion of the wiring. Alumi-
num oxide may also build up at the termination causing
hot spots and eventual failure. If aluminum wiring is
used to supply power to the unit, AL-CU compression
fittings should be used to transition from aluminum to
copper. This transition should be done in an external
box separate to the power panel. Copper conductors
can then be run from the box to the unit.
A 120-1-60, 15 A source must be supplied for the con-
trol panel through a fused disconnect when a control
panel transformer (optional) is not provided. See Fig-
ure 8 on page 40.
See unit wiring diagrams for eld and
power wiring connections, chilled water
pump starter contacts, alarm contacts,
compressor run status contacts, PWM
input, and load limit input. See Section 8:
Unit operation for a detailed description
of operation concerning aforementioned
contacts and inputs.
The removable conduit entry plates, lo-
cated on the bottom of the power panel
enclosure, must be removed from the
enclosure prior to using tools to cut out
the appropriate size knockouts for con-
duit entry. There are also predetermined
knockout holes located in the control sec-
tion of the power panel.
Do not make any penetrations into the en-
closure, except through the conduit entry
plates when they are removed from the
enclosure. Failure to remove the conduit
entry plates prior to cutting appropriately
sized knockouts can result in an arc ash
event which can cause damage to the
equipment or injury to personnel.
Use a tool that is designed to cut large
diameter wire to cut the incoming power
and ground wiring to length outside of the
enclosure. Do not use a grinder, recipro-
cating saw, or any similar tool to cut wires
to length. Failure to use the appropriate
tool to cut wiring can result in an arc
ash event which can cause damage to the
equipment or injury to personnel.
Compressor heaters
Compressor heaters are standard. ZP103, ZP120 and
ZP137 compressors use 90 W heaters; ZP180 compres-
sors use 70 W heaters; ZP235 compressors use 120 W
heaters. If power is OFF more than two hours, the
crankcase heaters must be energized for 18 hours to 24
hours before restarting a compressor. This ensures that
liquid slugging and oil dilution does not damage the
compressors on start.
Relief valves
Relief valves are located on both the high and low
pressure side of the piping. High side relief valve pres-
sure setting is 650 psig. Low side relief valve pressure
setting is 450 psig.
High pressure cutout
A high pressure cutout is installed in the discharge pip-
ing of each system. The cutout opens at 585 ± 10 psig
and closes at 440 ± 25 psig.
Electrical wiring
Field wiring
Power wiring must be provided through a fused dis-
connect switch to the unit terminals (or optional mold-
ed disconnect switch) in accordance with N.E.C. or
local code requirements. Minimum circuit ampacity
and maximum dual element fuse size are given in the
Electrical data on page 45.
A 120-1-60, 15 A source must be supplied for the con-
trol panel through a fused disconnect when a control
panel transformer (optional) is not provided. See Fig-
ure 4 on page 22 and Figure 10 on page 41.
See Figure 3 on page 21 and Figure 10 on page
41 and unit wiring diagrams for field and power wir-
ing connections. See Section 8: Unit operation for a
detailed description of operation concerning unit con-
tacts and inputs.
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