McQuay IM 987 51
Electrical Installation
Field Control Wiring
Units are available with several control arrangements which
may require low voltage field wiring. Detailed descriptions of
various field control wiring options and requirements are
included in the “Field Wiring” section of IM 919, “MicroTech
III® Unit Controller for Applied Rooftop and Self-Contained
Systems.” Refer to the unit wiring diagrams for additional
installation information.
Wiring must comply with applicable codes and ordinances.
The warranty is voided if wiring is not in accordance with
these specifications.
All field control wiring connections are made at the class II
terminal block TB2, which is located in the main control panel.
Field wiring connections to the 115-volt receptacle and lights
are made at terminal block TB7, which is also located in the
main control panel. Refer to Figure 59 and "Control Panel"‚
page 5. Two 7/8" knockouts are provided for wire entry.
Figure 59: Field Control Wiring Connections
Interconnecting wiring enters the air handler unit through 7/8"
knockouts in the bottom of the main control panel. The
interconnecting wiring is connected to TB4 in the air handler
unit. Refer to Figure 60. A 7/8" knockout is also available in
the end of the unit base as shown in Figure 59.
Note: If a single conduit containing 24V and 115V wiring is run
above the roof line between the air handler and
condensing units, install the 24V wiring as a NEC Class I
wiring system.
Figure 60: Interconnecting Control Wiring
Main control panel
24V field terminal
block (TB2)
Control wiring raceway
cover (remove for access
to harness from main control
box to unit-mounted
control devices)
WARNING
Electrical shock hazard. Can cause severe injury or death.
Connect only low voltage NEC Class II circuits to terminal block
TB2.
Reinstall and secure all protective deadfront panels when the
wiring installation is complete.
DS2
PB1/DS1
TB4
Main
ontrol
panel
To
condensi
unit
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