Single Point Boxes And Supplementary Fuses; Safety Devices; Completing Heater Installation - Bryant 547K 04-07 Series 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
installed directly under the unit control box, just to the left of
the partition separating the indoor section (with electric heat-
ers) from the outdoor section. The single point box has a
hinged access cover. See Fig. 38.
Control Wiring
Foam Power
Wiring
Fig. 38 — Typical Single Point Installation
On 547K units, all fuses are 60A. Single point boxes contain-
ing fuses for 208/230-v applications use UL Class RK5 250-v
fuses (Bussmann FRNR 60 or Ferraz Shawmut TR 60R).
™1
Single point boxes for 460-v and 575-v applications use UL
Class T 600-v fuses (Bussmann
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.)

Safety Devices

CRHEATERS323A00-341A00 electric heater applications use
a combination of 24-v control side break/auto-reset, line-
break/non-resettable "one shot" limit switches and a fan sta-
tor/manual reset limit switch to protect the unit against over-
temperature situations.
Line-break/auto-reset limit switches, 24-v 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. 39. These are accessed through the indoor access
panel. Remove the switch by removing 2 screws into the base
plate and extracting the existing switch.
Fan stator/manual reset limit switch is located in the side plate
of the indoor (supply) fan housing. See Fig. 39.
1. Third-party trademarks and logos are the property of their respective
owners.
Heater Heater
Relay Mounting Screws
JJS 60 or Ferraz Shawmut
™1
Control Side
Automatic Reset
Limit Switches
Fig. 39 — Typical Location of Heater Limit Switches (3-
phase heater shown)

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
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.
LOW-VOLTAGE CONTROL CONNECTIONS
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 the
ORN lead to terminal TB4-1. Connect the VIO lead to terminal
TB4-2. Connect the BRN lead to terminal TB4-3. See Fig. 40.
T
UCB
2 PNK
3 ORN
TRAN 1
C
ORN
1
TB4
VIO
Field
Connections
Fig. 40 — Accessory Electric Heater Control Connections
24
Stator Manual
Reset Limit
Switch
Line Break
"One Shot"
Limit Switches
PNK BRN
2 3
VIO BRN BRN
Elec Htr
VIO HR2 BRN
VIO HR1 BRN
HR1: Heater Circuit 1
HR2: Heater Circuit 2
(if two-circuit module installed)