31
Fig. 53 — Electric Heater Control Connections - Heat Pump with CRHEATER369A00, 376A00, 383A00
Fig. 54 — Heater Wiring
Fig. 55 — Heater Wiring and Covers
UNIT POWER SUPPLY WIRING – ALL UNITS
NOTE: Installers of unit power supply wiring connecting to these
air conditioning and heat pump units must be familiar with
applicable requirements of the National Electrical Code (NFPA
Standard 70), Articles 440, 430 and 424 dealing with multiple load
systems incorporating refrigeration compressors, motors and
electric heating. Installers must also be familiar with and observe
all local codes regarding unit power supply wiring.
In most instances, adding electric heaters to these units will result
in an increase in unit power supply wire size compared to base
unit electrical loads. These changes may also impact the size
selection of the branch circuit overload protection device and the
unit safety disconnect switch. Check the unit’s informative data
label (see Fig. 2-5 for examples) for minimum wiring sizing
ampacity for full combined load (including power exhaust if also
installed), for branch circuit protection size (a maximum value)
and for unit minimum disconnect switch size.
All wiring that terminates at a unit-mounted terminal must be
selected from wiring materials under the NEC
Table 310.15(B)(16), 75 C (or higher) column only. Check
specifications for external disconnect lug sizes to determine if
60 C wiring materials may be used between branch circuit origin
and the disconnect switch.
There are four different situations that an installer can encounter
with these units. Three are for new unit installations (base unit has
not been connected to a power supply already): Unit without
factory disconnect switch, unit with factory disconnect switch and
unit with factory HACR breaker. The fourth situation is for an
existing unit already connected to a power supply and the heaters
are being retrofitted. For each situation, there is usually a without
single point box and a with single point box condition. Each
situation is discussed below.
New Unit Without Factory Disconnect or HACR
INSTALLATION WITHOUT SINGLE POINT BOX
Unit power supply wires from the external (field-supplied)
disconnect switch are connected to the base unit’s power
TRAN2
HC4
HC3
HR4
HR3
BRN
BRN
BRN
BRN
BRN
BRN
BRN
HR3
HR4
RED
RED
TB4
RED
ORN
ORN
EHR
VIO
TB4
RED
TB4
LS1
LS1
RED
HR2
BRN
HR1
BRN
ORN
ORN
VIO
Terminal Block 4
(TB4)
Heater Cover
Terminal Block 4
(TB4)
Heater Covers
Table 13 — Device Infoplates
DEVICE
INFOPLATE DESIGNATION
POWER SUPPLY WIRE
MIN CKT Amps
BRANCH CIRCUIT
PROTECTION
Fuse Or HACR Breaker
DISCONNECT SWITCH
Minimum Unit Disconnect