Routing Through Bottom of Unit — If wiring is brought in through bottom of unit, use field-supplied watertight conduit to route power wiring through the 31/2-in. diameter hole provided in the unit basepan.
Install conduit connector in unit basepan as shown in Fig. 4-9. Route power and ground lines through connector to terminal connections in unit control box as shown on unit wiring diagram and Fig. 19.
Use strain relief going into control box through 35/8-in. diameter hole provided. After wires are in unit control box, connect to power terminal block (see Power Wiring section on page 20).
Low-voltage wiring must be run in watertight conduit from the basepan to control box and through 7/8-in. diameter hole provided in bottom of unit control box. Field-supplied strain relief must be used going into the box. After wiring is in control box, make connections to proper terminals on terminal blocks (see Field Control Wiring section on this page).
Routing Through Side of Unit — Route power wiring in field-supplied watertight conduit into unit through 21/2-in. (siz- es 020-035) or 3-in. (sizes 036-060) hole.
Use field-supplied strain relief going into control box through 35/8-in. diameter hole provided. After wires are in unit control box, connect to power terminal block (see Power Wir- ing section on page 20).
Bring low-voltage control wiring through the 7/8-in. diame- ter hole provided in the condenser section side post. Use strain relief going into 7/8-in. diameter hole in bottom of unit control box.
After wiring is in control box, make connection to proper terminals on terminal blocks (see Field Control Wiring section below).
IMPORTANT: The VAV (variable air volume) units use variable frequency drives, which generate and can radiate radio frequency energy. If units are not installed and used in accordance with these instructions, they may cause radio interference. They have been tested and found to comply with limits of a Class A computing device as defined by FCC (Federal Communications Commission) regulations, Subpart J of Part 15, which are designed to provide reason- able protection against such interference when operated in a commercial environment.
WARNING
The unit must be electrically grounded in accordance with local codes and NEC ANSI/NFPA 70 (National Fire Protection Association). Electrical shock could cause per- sonal injury.
Affix crankcase heater sticker (located in the installers packet) to unit disconnect switch.
Voltage to compressor terminals during compressor operation must be within the voltage range indicated on the unit name- plate. Phases must be balanced within 2%.
Use the formula in Tables 8A and 8B to determine the per- centage of voltage imbalance.
IMPORTANT: If the supply voltage phase imbalance is more than 2%, contact your local electric utility company immediately.
Unit failure as a result of operation on improper line voltage or excessive phase imbalance constitutes abuse and may cause damage to electrical components.
IMPORTANT: On 208/230-v units, transformers 1-5 are wired for 230-v. If 208/230-v unit is to be run with 208-v power supply, the transformers must be rewired as follows:
For transformer 1 move the black wires connected to termi- nal H2 and connect it to terminal H3.
For transformers 2-4, that are used for the 24-volt control circuits, connect as follows:
1.Remove cap from red (208 v) wire.
2.Remove cap from spliced orange (230 v) wire. Discon- nect orange wire from black unit power wire.
3.Cap orange wire.
4.Splice red wire and black unit power wire. Cap wires.
If the unit is equipped with the optional convenience outlet connect the yellow wire to H2 on transformer 5.
IMPORTANT: BE CERTAIN UNUSED WIRES ARE CAPPED. Failure to do so may damage the transformers.
FIELD CONTROL WIRING — The 48A Series units sup- port a large number of control options that can impact the field control wiring.
The control options that the unit can provide relate to the following parameters:
•CV (constant volume), VAV (variable air volume), VVT® (variable volume variable temperature) or Carrier TEMP system control operation.
•Stand-alone with a thermostat (CV) or with a space sen- sor (CV and VAV)
•Network application with CCN (Carrier Comfort Network®) or other networks
•Demand ventilation with CO2 sensor
•Economizer and economizer with changeover control
•Staged gas heat
•Building and duct static pressure control
•Fire shutdown and smoke control
•Diagnostics and monitoring
For constant volume applications a thermostat (T-Stat) or space temperature sensor (SPT) will be required.
T-STAT (Conventional Thermostat) — Unit can be con- trolled with a Carrier-approved accessory electro-mechanical or electronic thermostat that has two stages of cooling, two stages of heating control and an output for indoor fan control. It may also include time of day scheduling or use the scheduling routines built into the ComfortLink™ controls.
Install thermostat according to the installation instructions included with accessory thermostat and the unit wiring dia- grams. Locate thermostat assembly on a solid interior wall in the conditioned space to sense average temperature.
Route thermostat cable or equivalent single leads of colored wire from subbase terminals through conduit into unit to low- voltage connection in the main control box. For thermostat TB4 connections see Fig. 20.
NOTE: For wire runs up to 50 ft, use no. 18 AWG (American Wire Gage) insulated wire (35 C minimum). For 50 to 75 ft, use no. 16 AWG insulated wire (35 C minimum). For over 75 ft, use no. 14 AWG insulated wire (35 C Minimum). All wire larger than no. 18 AWG cannot be directly connected at the thermostat and will require a junction box and splice at the thermostat. Set heat anticipator settings as follows:
| SIZE | STAGE 1 | STAGE 2 |
| (W1) ON | (W1 and W2) ON |
| |
| 020-050 | 0.24 | 0.13 |
| 051, 060 | 0.36 | 0.13 |
Settings may be changed slightly to provide a greater degree of comfort for a particular installation.
