Step 10 — Install Electrical Connections
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
The unit cabinet must have an uninterrupted, unbroken electrical ground. This ground may consist of an electrical wire connected to the unit ground screw in the control compartment, or conduit approved for electrical ground when installed in accordance with NEC, NFPA 70 National Fire Protection Association (latest edition) (in Canada, Canadian Electrical Code CSA C22.1) and local electrical codes.
!CAUTION
UNIT COMPONENT DAMAGE HAZARD
Failure to follow this caution may result in damage to the unit being installed.
1.Make all electrical connections in accordance with NEC NFPA 70 (latest edition) and local electrical codes governing such wiring. In Canada, all electrical connections must be in accordance with CSA standard C22.1 Canadian Electrical Code Part 1 and applicable local codes. Refer to unit wiring diagram.
2.Use only copper conductor for connections between field-supplied electrical disconnect switch and unit. DO NOT USE ALUMINUM WIRE.
3.Be sure that high-voltage power to unit is within operating voltage range indicated on unit rating plate. On 3-phase units, ensure phases are balanced within 2 percent. Consult local power company for correction of improper voltage and/or phase imbalance.
4.Insulate low-voltage wires for highest voltage contained within conduit when low-voltage control wires are in same conduit as high-voltage wires.
5.Do not damage internal components when drilling through any panel to mount electrical hardware, conduit, etc.
High-Voltage Connections
When routing power leads into unit, use only copper wire between disconnect and unit. The high voltage leads should be in a conduit until they enter the duct panel; conduit termination at the duct panel must be watertight.
The unit must have a separate electrical service with a field-supplied, waterproof disconnect switch mounted at, or within sight from, the unit. Refer to the unit rating plate, NEC and local codes for maximum fuse/circuit breaker size and minimum circuit amps (ampacity) for wire sizing.
The field-supplied disconnect switch box may be mounted on the unit over the high-voltage inlet hole when the standard power and low-voltage entry points are used (See Fig. 2 and 3 for acceptable location).
See unit wiring label (Fig. 15 and 16) and Fig. 10 for reference when making high voltage connections. Proceed as follows to complete the high-voltage connections to the unit.
Single phase units:
1.Run the high-voltage (L1, L2) and ground lead into the control box.
2.Connect ground lead to chassis ground connection.
3.Locate the black and yellow wires connected to the line side of the contactor.
4.Connect field L1 to black wire on connection 11 of the compressor contactor.
5.Connect field wire L2 to yellow wire on connection 23 of the compressor contactor.
Three-phase units:
1.Run the high-voltage (L1, L2, L3) and ground lead into the control box.
2.Connect ground lead to chassis ground connection.
3.Locate the black and yellow wires connected to the line side of the contactor.
4.Connect field L1 to black wire on connection 11 of the compressor contactor.
5.Connect field wire L3 to yellow wire on connection 13 of the compressor contactor.
6.Connect field wire L2 to blue wire from compressor.
Special Procedures for 208-V Operation
!WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal injury or death.
Make sure the power supply to the unit is switched OFF before making any wiring changes. Tag the disconnect switch with a suitable warning label. With disconnect switch open, move black wire from transformer (3/16 in.) terminal marked 230 to terminal marked 200. This retaps transformer to primary voltage of 208 vac.
!WARNING
ELECTRICAL SHOCK AND EXPLOSION HAZARD
Failure to follow this warning could result in personal injury or death.
Before making any wiring changes, make sure the gas supply is switched off first. Then switch off the power supply to the unit and install lockout tag.
Control Voltage Connections
Do not use any type of power-stealing thermostat. Unit control problems may result.
Use no. 18 American Wire Gage (AWG) color-coded, insulated (35_C minimum) wires to make the control voltage connections between the thermostat and the unit. If the thermostat is located more than 100 ft (30.5 m) from the unit (as measured along the control voltage wires), use no. 16 AWG color-coded, insulated (35_C minimum) wires.
Locate the seven (eight on 3-phase) low voltage thermostat leads in 24 volt splice box. See Fig. 10 for connection diagram. Run the low-voltage leads from the thermostat, through the control wiring inlet hole grommet (Fig. 2 and 3), and into the low-voltage splice box. Provide a drip loop before running wires through panel. Secure and strain relief all wires so that they do not interfere with operation of unit. A gray wire is standard on 3-phase unit for connection to an economizer.
