Electric Heaters; Single Point Boxes And Supplementary Fuses; Single Point Boxes Without Fuses - Carrier 50KC04 Installation Instructions Manual

Electric Heaters

The 50KC units may be equipped with field-installed accessory
electric heaters. The heaters are modular in design, with heater
frames holding open coil resistance wires strung through ceramic
insulators, line-break limit switches and a control contactor. One
or two heater modules may be used in a unit.
Heater modules are installed in the compartment below the indoor
(supply) fan outlet. Access is through the indoor access panel.
Heater modules slide into the compartment on tracks along the
bottom of the heater opening. See Fig. 34-36.
Not all available heater modules may be used in every unit. Use
only those heater modules that are UL listed for use in a specific
size unit. Refer to the label on the unit cabinet for the list of ap-
proved heaters.
DISCONNECT MOUNTING
LOCATION
UNIT BLOCK-OFF
PANEL
Fig. 34 — Typical Access Panel Location (3-5 Ton)
DISCONNECT EMT OR RIGID CONDUIT
MOUNTING (FIELD-SUPPLIED)
LOCATION
SINGLE POINT
MAIN BRACKET AND BOX
CONTROL CONDUIT MOUNTING
BOX DRIP BOOT SCREW
CONTROL WIRE TERMINAL BLOCK
Fig. 35 — Typical Component Location
INDOOR
OUTDOOR ACCESS
ACCESS PANEL PANEL
SINGLE CENTER MANUAL RESET
POINT BOX POST LIMIT SWITCH
HEATER
COVERS
HEATER HEATER HEATER
MODULE MODULE MOUNTING
(LOCATION 1) (LOCATION 2) BRACKET
Fig. 36 — Typical Module Installation

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 dis-
tribution and fuse blocks. The single point box will be installed di-
rectly under the unit control box, just to the left of the partition
separating the indoor section (with electric heaters) from the out-
door section. The single point box has a hinged access cover. See
Fig. 37. 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 for details on tap con-
nections.
All fuses on 50KC units are 60-A. (Note that all heaters are quali-
fied 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 in-
stallation 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. 37 — Typical Single Point Installation
20
TRACK
FLANGE