Carrier 50HT-A07 Installation Instructions Manual page 19

Single Point Boxes and Supplementary Fuses — When
the unit MOCP device value exceeds 60- - A, unit- - mounted
supplementary fuses are required for each heater circuit.
These fuses are included in accessory Single Point Boxes,
with power distribution and fuse blocks. The single point
box will be installed directly under the unit control box,
just to the left of the partition separating the indoor
section (with electric heaters) from the outdoor section.
The Single Point Box has a hinged access cover. See
Fig. 31. The Single Point Box also includes a set of
power taps and pigtails to complete the wiring between
the Single Point Box and the unit's main control box
terminals. Refer to the accessory heater and Single Point
Box installation instructions
connections.
All fuses on 50HT units are 60- - A. (Note that all heaters
are qualified for use with a 60- - A fuse, regardless of actual
heater ampacity, so only 60- - A fuses are necessary.)
Single Point Boxes without Fuses — Unit heater
applications not requiring supplemental fuses require a
special Single Point Box without any fuses. The accessory
Single Point Boxes contain a set of power taps and pigtails
to complete the wiring between the Single Point Box and
the unit's main control box terminals. Refer to accessory
heater and Single Point Box installation instructions for
details on tap connections.
CONTROL
BOX
BUSHING
SINGLE
POINT BOX
MOUNTING
SCREWS
DRIP BOOT
BRACKET
MOUNTING
SCREWS
POWER
WIRES
FOAM
BUSHING
HEATER
RELAYS
HEATER
MOUNTING
SCREWS
Fig. 31 - - Typical Single Point Installation
Low- - Voltage Control
low- - voltage control leads from the heater module(s) - -
VIO and BRN (two of each if two modules are installed;
identify for Module #1) - - to the 4- - pole terminal board
TB4 located on the heater bulkhead to the left of Heater
#1. Connect the VIO lead from Heater #1 to terminal
TB4- - 1. For 2 stage heating, connect the VIO lead from
Heater #2 to terminal TB4- - 2. For 1 stage heating with 2
heater modules connect the VIO lead from both Heater #1
and #2 to terminal TB4- - 1. Connect both BRN leads to
terminal TB4- - 3. See Fig. 32.
for details on
C08136
Connections —
Pull
CTB
CONTL
BOARD
2
VIO
3
ORN
12
BRN
tap TB4
Field
Connections
Fig. 32 - - Accessory Electric Heater Control
Smoke Detectors —
Smoke detectors are available as factory- - installed options
on 50HT models. Smoke detectors may be specified for
Supply Air only or for Return Air without or with
economizer or in combination of Supply Air and Return
Air. Return Air smoke detectors are arranged for vertical
return configurations only. All components necessary for
operation are factory- - provided and mounted. The unit is
factory- - configured
shutdown operation; additional wiring or modifications to
unit terminal board may be necessary to complete the unit
and smoke detector configuration to meet project
requirements.
Units equipped with factory- - optional Return Air smoke
detectors require a relocation of the sensor module at unit
installation. See "Completing Installation of Return Air
Smoke Sensor:" for details.
System
the
The smoke detector system consists of a four- - wire
controller and one or two sensors. Its primary function is
to shut down the rooftop unit in order to prevent smoke
from circulating throughout the building. It is not to be
used as a life saving device.
Controller
The controller (see Fig. 33) includes a controller housing,
a printed circuit board, and a clear plastic cover. The
controller can be connected to one or two compatible duct
smoke sensors. The clear plastic cover is secured to the
housing with a single captive screw for easy access to the
wiring terminals. The controller has three LEDs (for
Power, Trouble and Alarm) and a manual test/reset button
(on the cover face).
19
BRN
ORN VIO
1 2 3
VIO VIO
BRN BRN
Elec Htr
VIO BRN
HR2
VIO
HR1 BRN
HR1: On Heater 1 in Position #1
HR2: On Heater 2 in Position #2 (if installed)
Connections
for immediate smoke
C08331
detector