FIELD CONNECTIONS
1.Main Power Ð Bring wires from the fused disconnect switch through hole in bottom rail of unit to control box
(Fig. 6 and 7) and connect terminals 11 , 12 , and
13 line side of terminal block TB1 (see Fig. 8 and 9A
or 9B). To comply with NEC Article 440-14, the discon- nect must be located within sight from and readily ac- cessible from unit.
2.24-v Control Power Ð Units have single point power con- nections. Control circuit is directly connected internally to unit. Maximum 24-v control circuit is 3 amps.
NOTE: Wire runs use the following insulated wire:
UNBALANCED 3-PHASE SUPPLY VOLTAGE Ð Never operate a motor where a phase imbalance in supply voltage is greater than 2%. Use the following formula to determine the percent voltage imbalance:
% Voltage Imbalance
= 100 x | max voltage deviation from average voltage | |
| average voltage |
|
Example: Supply voltage is 240-3-60.
AB = 243 v
BC = 236 v
AC = 238 v
LENGTH | INSULATED WIRE SIZE* | ||
AWG | mm2 | ||
| |||
18 | 0.82 | ||
| 16 | 1.30 | |
Over 75 | 14 | 2.08 | |
Average Voltage =
243 + 236 + 238
3
AWG Ð American Wire Gage *35 C minimum.
3.Control Circuit Interlock Ð An air¯ow switch may be installed in the indoor air handler to prevent unit from running when indoor air is not ¯owing. This switch (no. HR81JE001) is available from Service Parts Center, or equivalent can be ®eld supplied. This should be electri- cally interlocked in the control circuit, between thermo-
= 239 volts
Determine maximum deviation from average voltage:
(AB) 243 − 23 9 = 4 v (BC) 239 − 23 6 = 3 v (AC) 239 − 23 8 = 1 v
Maximum deviation is 4 v. Determine percent voltage imbalance:
stat TC1 (stage 1, cooling) and terminal 2 
Y1 on TB3. See Fig. 8 for typical ®eld wiring. This is in the
% Voltage Imbalance = 100 x
4
cuit. Wires must be run in conduit with ground wire.
4.Transformer Connections Ð See unit wiring label dia- gram, notes 1 and 2, located behind compressor compart- ment end access door.
IMPORTANT: Ensure power to the crankcase heater is always on (except when servicing the unit). If cir- cuit breaker inside unit shuts down the compressor, crank- case heater remains on.
239
= 1.7%
This amount of phase imbalance is satisfactory as it is be- low the maximum allowable 2%.
IMPORTANT: Contact your local electric utility com- pany immediately if the supply voltage phase imbal- ance is more than 2%.
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