Step 5 — Make Electrical Connections
WARNING
Electrical shock can cause personal injury and death. Shut off all power to this equipment during installation. There may be more than one disconnect switch. Tag all discon- nect locations to alert others not to restore power until work is completed.
POWER SUPPLY — The electrical characteristics of the available power supply must agree with the unit nameplate rating. Supply voltage must be within the limits shown. See Tables 5-11 for electrical and configuration data.
FIELD POWER CONNECTIONS (See Fig. 37) — All power wiring must comply with applicable local and national codes. Install field-supplied, branch circuit fused disconnect(s) of a type that can be locked off or open. Disconnect(s) must be locat- ed within sight and readily accessible from the unit in compli- ance with NEC Article 440-14 (U.S.A.). See Tables 5-11 for unit electrical data.
IMPORTANT: The 30XA units have a factory-installed option available for a non-fused disconnect for unit power supply. If the unit is equipped with this option, all field power wiring should be made to the non-fused disconnect since no terminal blocks are supplied.
Maximum wire size that the unit terminal block or non- fused disconnect will accept is 500 kcmil.
POWER WIRING — All power wiring must comply with ap- plicable local and national codes. Install field-supplied branch circuit fused disconnect per NEC of a type that can be locked OFF or OPEN. Disconnect must be within sight and readily ac- cessible from the unit in compliance with NEC Article 440-14. In the power box, 7/8 in. holes are provided for power entry. The holes will need to bee enlarged to accept the appropriate conduit. NEC also requires all conduits from a conditioned space to the power box(es) be sealed to prevent airflow and moisture into the control box.
The 30XA units require 1 or 2 power supplies, depending on the unit and circuit voltage. See Tables 5-8 for chiller elec- trical data. Cooler and pump heaters, if factory-installed, are wired in the control circuit. Heaters on chillers with the option- al control transformer will be capable of operation only when the main power supply to the chiller is on. On chillers with sep- arate control power, the heaters are capable of operation when- ever the control power is supplied.
FIELD CONTROL POWER CONNECTIONS (See Fig. 37) — All units require 115-1-60 control circuit power, unless the control transformer option is installed.
Terminals TB5-1 and TB5-2 are provided for field installa- tion of a chilled water (fluid) pump interlock (CWPI). The chilled water (fluid) flow sensor (CWFS) is factory installed. These devices are to be installed in series. Contacts must be rated for dry-circuit applications capable of handling a 24-vac at 50 mA load.
An accessory remote on-off switch can be wired into TB5-9 and TB5-10. Contacts must be rated for dry-circuit applications capable of handling a 24-vac at 50 mA load.
CAUTION
Do not use interlocks or other safety device contacts connected between TB5-9 and TB5-10 as remote on-off. Connection of safeties or other interlocks between these 2 terminals will result in an electrical bypass if the ENABLE-OFF-REMOTE contact switch is in the ENABLE position. If remote on-off unit control is required, a field-supplied relay must be installed in the unit control box and wired as shown in Fig. 37. Failure to wire the remote on-off as recommended may result in tube freeze damage.
Terminals 11 and 13 of TB5 are for control of the chilled water pump 1 (PMP1) starter. Terminals 13 and 15 of TB5 are for control of the chilled water pump 2 (PMP2) starter.
CARRIER COMFORT NETWORK® COMMUNICATION BUS WIRING (See Fig. 38) — The communication bus wiring is a shielded, 3-conductor cable with drain wire and is field supplied and installed in the field.
The system elements are connected to the communication bus in a daisy chain arrangement. The positive pin of each system element communication connector must be wired to the positive pins of the system elements on either side of it. This is also required for the negative and signal ground pins of each system element. Wiring connections for CCN (Carrier Comfort Network) should be made at TB (terminal block) 3. Consult the CCN Contractor’s Manual for further information. See Fig. 38.
NOTE: Conductors and drain wire must be 20 AWG (American Wire Gage) minimum stranded, tinned copper. Individual conductors must be insulated with PVC, PVC/ nylon, vinyl, Teflon, or polyethylene. An aluminum/polyester 100% foil shield and an outer jacket of PVC, PVC/nylon, chrome vinyl, or Teflon with a minimum operating tempera- ture range of –4 F (–20 C) to 140 F (60 C) is required. See Table 12 for a list of manufacturers that produce CCN bus wiring that meet these requirements.
It is important when connecting to a CCN communication bus that a color coding scheme be used for the entire network to simplify the installation. It is recommended that red be used for the signal positive, black for the signal negative, and white for the signal ground. Use a similar scheme for cables contain- ing different colored wires. At each system element, the shields of its communication bus cables must be tied together. If the communication bus is entirely within one building, the result- ing continuous shield must be connected to a ground at one point only. If the communication bus cable exits from one building and enters another, the shields must be connected to grounds at the lightning suppressor in each building where the cable enters or exits the building (one point per building only).
To connect the unit to the network:
1.Turn off power to the control box.
2.Cut the CCN wire and strip the ends of the red (+), white (ground), and black (–) conductors. Substitute appropri- ate colors for different colored cables.
3.Connect the red wire to (+) terminal on TB3 of the plug, the white wire to COM terminal, and the black wire to the
(–) terminal.
