Operating instructions

34 IMM AGSB-60
Electrical Data
Field Wiring
General
Wiring must comply with all applicable codes and ordinances. Damage to the equipment caused
by wiring not complying with specifications is not covered under warranty.
An open fuse or circuit breaker indicates a short, ground, or overload. Before replacing a fuse or
restarting a compressor or fan motor, the trouble must be found and corrected.
Copper wire is required for all power lead terminations at the unit and copper must be used for all
other wiring to the unit.
AGS units can be ordered with main power wiring for either multiple-point power (standard) or
single-point connection (optional).
If the standard multiple-point power wiring is ordered, power connections are made to the
individual circuit power blocks in power panels located between the condenser sections. Two
connections are required for models AGS 230 through 320 and three are required for models AGS
340 through 475. See the dimension drawings on pages 30 and 31 for detailed locations. Separate
disconnects are required for each electrical circuit if McQuay factory-mounted disconnects with
through-the-door handles are not ordered.
If the optional single-point power connection is ordered, a single large power connection point is
provided and located in a box on the base of the unit. See the dimension drawings on pages 30
and 31 for the location. Factory wiring from the box to the individual compressor power panels
on the unit is sized in accordance with the National Electrical Code. A disconnect is required and
can be furnished as a factory option. Each circuit has a factory wired compressor isolation circuit
breaker. The 115-volt control transformer is factory mounted and wired.
It can be desirable to have the unit evaporator heaters on a separate disconnect switch from the
main unit power supply so that the unit power can be shut down without defeating the freeze
protection provided by the cooler heaters. See page 21 for details.
CAUTION
The heaters come from the factory connected to the control power circuit. If desired, the 3 KVA
control transformer can be unwired and a field 115-volt power source wired to terminals TB1-1 and
TB1-2 in the control panel for circuit #1 (do not wire directly to the heater). If this is done, the
disconnect switch should be clearly marked to avoid accidental deactivation of the heater during
freezing temperatures. Exposed chilled water piping also requires protection.
Power blocks are standard on all size units. Multi-point power connections can have circuit
breakers as an option. The single-point circuit breaker option has a main circuit breaker and
individual breakers in each panel.
CAUTION
AGS unit compressors are single-direction rotation compressors and can be damaged if rotated in the
wrong direction. For this reason proper phasing of electrical power is important. Electrical phasing
must be A, B, C for electrical phases 1, 2 and 3 (A=L1, B=L2, C=L3) for single or multiple point wiring
arrangements. The solid-state starters contain phase reversal protection.
DO NOT ALTER THE WIRING TO THE STARTERS.