Carrier 38AKS028-044 dimensions Length Insulated Wire Size AWG, Mm2, 50-75

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
0-50	18	0.82
50-75	16	1.30
Over 75	14	2.08

Average Voltage =

243 + 236 + 238

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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 24-v cir-

% Voltage Imbalance = 100 x

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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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