Single Point Boxes And Supplementary Fuses; Safety Devices; Completing Heater Installation - Carrier WeatherMaster 50HCQ04-12 Service And Maintenance Instructions

Single Point Boxes and Supplementary Fuses

When the unit MOCP device value exceeds 60A, 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 in-
stalled 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 ac-
cess cover. See Fig. 40.
SINGLE
POINT
BOX
FIELD POWER
CONNECTIONS
HINGED
COVER
Fig. 40 — Typical Single Point Installation
On 50HCQ units, all fuses are 60A. Single point boxes con-
taining fuses for 208/230V applications use UL Class RK5
250V fuses (Bussmann FRNR 60 or Shawmut TR 60R). Single
point boxes for 460V and 575V applications use UL Class T
600V fuses (Bussmann JJS 60 or Shawmut A6T 60). (Note that
all heaters are qualified for use with a 60A fuse, regardless of
actual heater ampacity, so only 60A fuses are necessary.)
On 07-09 size units, unit heater applications not requiring sup-
plemental fuses require a special Single Point Box without any
fuses. Connect power supply conductors to heater conductors
and field-supplied base unit power tap leads (see "Completing
Heater Installation") inside the empty Single Point Box using
UL-approved connectors.

Safety Devices

Electric heater applications other than CRHEATER113B00-
116B00, 128B00, and 129B00 use a combination of 24v con-
trol side break/auto-reset or line-break/auto-reset limit switch-
es and a pilot-circuit/manual reset limit switch to protect the
unit against over-temperature situations.
CRHEATER113B00-116B00, 128B00, and 129B00 electric
heater applications use a combination of 24v control side
break/auto-reset, line-break/non-resettable "one shot" limit
switches, and a pilot-circuit/manual reset limit switch to pro-
tect the unit against over-temperature situations.
Line-break/auto-reset limit switches, 24v control side break/
auto-reset and line-break/non-resettable "one shot" limit
switches are mounted on the base plate of each heater module.
See Fig. 41. These are accessed through the indoor access pan-
el. 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. 38 and Fig 41.

Completing Heater Installation

FIELD POWER CONNECTIONS
Tap conductors must be installed between the base unit's field
power connection lugs and the Single Point Box (with or with-
out fuses). See Fig. 40. Refer to unit wiring schematic. Use
copper wire only. For connection using the single point box
A L LI ED PA
C O R P .
MO D E L N O.
O D
E RI A L N O.
22 .2
ISTED AIR
UIP NDITIONING ACCESS 2 3 1
346N.
3
P / N 2 - - 5610 - - 4
REV
25
without fuses, connect the field power supply conductors to the
heater power leads and the field-supplied tap conductors inside
the Single Point Box. Use UL approved pressure connectors
(field-supplied) for these splice joints.
A L LI E DPA
C O R P .
M O D E LN O.
O D
E R IA L N O.
2 2.2
ISTED AIR
NDITIONING 1
UIP ACCESS 2 3
346N.
3
P/ N 2- - 5610 4 - - REV
Fig. 41 — Typical Location of Heater Limit Switches
(3-phase heater shown)
LOW-VOLTAGE CONTROL
EXCEPT CRHEATER128B00-129B00)
Pull the low-voltage control leads from the heater module(s) —
VIO and BRN (two of each if two modules are installed; iden-
tify for Module #1) — to the 4-pole terminal board TB4 locat-
ed on the heater bulkhead to the left of Heater #1. Connect the
VIO leads from both Heater #1 and #2 to terminal TB4-1. Con-
nect both BRN leads to terminal TB4-3. See Fig. 42.
Fig. 42 — Accessory Electric Heater Control
Connections (HP-2, Size 06, 575V Only)
LOW-VOLTAGE CONTROL
(CRHEATER128B00-129B00)
Pull the low-voltage control leads from the heater module(s) —
ORN, VIO and BRN — to the 4-pole terminal board TB4 lo-
cated on the heater bulkhead to the left of Heater #1. Connect
both the ORN and VIO lead to terminal TB4-1. Connect the
BRN lead to terminal TB4-3. See Fig. 43.
PILOT--- CIRCUIT/MANUAL
RESET LIMIT SWITCH
LINE--- BREAK
LIMIT SWITCHES
CONNECTIONS (ALL
CONNECTIONS