22
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 insta lled directly under the unit control box,
just to the left of the partition separating t he indoor
section (with electric heaters) from the outdoor section.
The Single Point Box has a hinged access cover. See Fig
30.
A
L
LIE
D
P
A
M
O
DE
L
N
O
.
ERI
A
L
N
O
.
C
O
R
P
.
11
13
21
23
O
D
2
2
.
2
3
1
2
3
ISTED
AIR
NDITIONING
UIP
ACCESS
346N
.
P
/ N
2-
5
6
1
0
-
4
REV
1
1
13
2
1
2
3
CONTROL
BOX
BUSHING
SINGLE
POINT BOX
MOUNTING
SCREWS
FOAM
BUSHING
DRIP BOOT
BRACKET
MOUNTING
SCREWS
HEATER
RELAYS
POWER
WIRES
HEATER
MOUNTING
SCREWS
C08136
Fig. 30 -- Typical Single Point Installation
On 50TC units, all fuses are 60--A. Single point boxe s
conta ining fuses for 208/230--V applications use UL Class
RK5 250--V fuses (Bussman FRNR 60 or Shawmut TR
60R). Single point boxes for 460--V and 575--V
applications use UL Class T 600--V fuses (Bussman JJS
60 or Shawmut A6T 60). (Note that all heaters are
qualified for use with a 60--A fuse, re gardless of actual
heater ampacity, so only 60--A fuses are necessary.)
Unit heater applications not re quiring supplemental fuses
do not require a Single Point Box. Connect power supply
conductors to heater conductors and field--supplied base
unit power tap leads (see text below re: “Completing
Heate r Installation”) below the unit’s main control box
using UL--approved connectors.
Safety Devices — Electric heater applications use a
combination of line--break/auto--reset limit switches and a
pilot--circuit/manual reset limit switch to protect the unit
against over--tempe rature situations.
Line --break/auto--reset limit switches are mounted on the
base plate of each heater module. See Fig. 31. These are
accessed through the indoor access panel. Remove the
switch by removing two screws into the base plate and
extracting the existing switch.
Pilot--circuit/manual reset limit switch is located in the
side plate of the indoor (supply) fan housing. See Fig. 28.
Completing Heater Installation
Field Power Connections — Field--supplied tap
conductors must be installed bet ween the base unit’s field
power connection lugs and the splice connection between
field power supply conductors and the conductors to t he
electric heater(s). Refer to unit wiring schematic. Use
copper wire only. Siz e these conductors based on the
MCA (Minimum Circuit Ampacity) value marked on the
50TC unit’s info plate for the base unit less electric heater
load. Use UL--approved pressure connectors
(field--supplied) for these splice joints.
ALLIED P
A
MODE
L
NO.
ERIAL
NO.
11
13
21
23
OD
3
1
23
ISTED
AIR
NDITIONING
U
I
P
ACCESS
34
6
N
.
P
/ N
2
-
5610-4
RE
V
Line-Break
Limit Switches
C08330
Fig. 31 -- Typical Location of Heater Limit Switches
(3--phase heater shown)
Low--Voltage Control Connections — Pull the
low--volta ge control leads from the he ater 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. Connect the VIO lead from Heater #2 to terminal
TB4--2. Connect both BRN leads to terminal TB4--3. See
Fig. 32.
LCTB
CONTL
BOARD
ORN
BRN
Field
Connections
HR1: On Heater 1 in Position #1
HR2: On Heater 2 in Position #2 (if installed)
2
3
12
13
VIO
ORN
VIO
BRN
VIO
BRN
BRN
VIO
2
TB4
VIO
HR2
HR1
BRN
VIO
BRN
Elec Htr
C08331
Fig. 32 -- Accessory Electric Heater Control
Connections
50TC
