76 RT-SVX36G-EN
Installation
PLUS
DSS = 1.15 X (LOAD 1 + LOAD 2 + LOAD 4)
Use the larger value of the two calculations to size the electrical service.
• Calculation #3 - SEHL (200/230 Volt) 20 - 75 Ton Dual Power Source Units
DSS = 1.15 X LOAD3 for the Electric heater AND Calculation #1 for the Refrigeration Components
Field Installed Control Wiring
The Rooftop Module (RTM) must have a mode input in order to operate the rooftop unit. The
flexibility of having several system modes depends upon the type of sensor and/or remote panel
selected to interface with the RTM. An overall layout of the various control options available for a
Constant Volume application, with the required number of conductors for each device, is illustrated
in Figure 34, p. 69. Figure 37, p. 85 illustrates the various control options with the required number
of conductors for a Variable Air Volume application.
Note: All field wiring must conform to NEC guidelines as well as state and local codes.
The various field installed control panels, sensors, switches, and contacts discussed in this section
require both AC and DC consideration. These diagrams are representative of standard applications
and are provided for general reference only. Always refer to the wiring diagram that shipped with
the unit for specific electrical schematic and connection information.
Controls Using 24 VAC
Before installing any connecting wiring, refer to Figure 9, p. 34 and Figure 10, p. 36 for the electrical
access locations provided on the unit and Ta b le 2 8 for AC conductor sizing guidelines, and;
1. Use copper conductors unless otherwise specified.
2. Ensure that the AC control wiring between the controls and the unit's termination point does
not exceed three (3) ohms/conductor for the length of the run.
Note: Resistance in excess of 3 ohms per conductor may cause component failure due to
insufficient AC voltage supply.
3. Be sure to check all loads and conductors for grounds, shorts, and mis-wiring.
WARNING
Hazardous Voltage!
Disconnect all electric power, including remote disconnects before servicing. Follow proper
lockout/tagout procedures to ensure the power can not be inadvertently energized. Failure to
disconnect power before servicing could result in death or serious injury.
WARNING
Proper Field Wiring and Grounding Required!
All field wiring MUST be performed by qualified personnel. Improperly installed and grounded
field wiring poses FIRE and ELECTROCUTION hazards. To avoid these hazards, you MUST
follow requirements for field wiring installation and grounding as described in NEC and your
local/state electrical codes. Failure to follow code could result in death or serious injury.
Table 28. AC Conductors
Distance from unit to control Recommended wire size
000-460 feet 18 gauge
461-732 feet 16 gauge
733-1000 feet 14 gauge
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