Bryant 551A operation manual Condensate Drain Piping Details, B. Field Control Wiring

Fig. 10 — Condensate Drain Piping Details

VI. STEP 6 — MAKE ELECTRICAL CONNECTIONS A. Field Power Supply

Unit is factory wired for voltage shown on nameplate.

When installing units, provide a disconnect, per NEC (National Electrical Code) requirements, of adequate size (Table 2). Electrical heater data is shown in Table 3.

All field wiring must comply with NEC and local require- ments.

Route power lines through control box access panel or unit basepan (Fig. 4 and 5) to connections as shown on unit wir- ing diagram and Fig. 11.

Operating voltage to compressor must be within voltage range indicated on unit nameplate. On 3-phase units, volt- ages between phases must be balanced within 2% and the current must be balanced within 10%.

CAUTION: The correct power phasing is critical in the operation of the scroll compressors. An incorrect phasing will cause the compressor to rotate in the wrong direction. This may lead to premature compres- sor failure.

Use the following formula to determine the percentage of voltage imbalance.

Percentage of Voltage Imbalance

=100 x max voltage deviation from average voltage average voltage

EXAMPLE: Supply voltage is 460-3-60.

AB = 452 v

BC = 464 v

AC = 455 v

455 + 464 + 455

Average Voltage =

3

= 1371 3

= 457

Determine maximum deviation from average voltage:

(AB) 457 – 452 = 5 v

(BC) 464 – 457 = 7 v

(AC) 457 – 455 = 2 v

Maximum deviation is 7 v.

Determine percent voltage imbalance:

Percentage of Voltage Imbalance = 100 x 7457

= 1.53%

This amount of phase imbalance is satisfactory as it is below the maximum allowable 2%.

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.

B. Field Control Wiring

Install a Bryant-approved accessory thermostat assembly according to the installation instructions included with the accessory. Locate thermostat assembly on a solid wall in the conditioned space to sense average temperature.

Route thermostat cable or equivalent single leads of colored wire from subbase terminals through conduit in unit to low- voltage connections as shown on unit label wiring diagram and in Fig. 12.

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 to the thermostat and will require a junction box and splice at the thermostat.

Set heat anticipator settings as indicated in Table 4. Settings may be changed slightly to provide a greater degree of com- fort for a particular installation.

TB1 MAXIMUM WIRE SIZE

	UNIT					VOLTAGE
	551A				208/230					460
	All				350 kcmil					2/0
					LEGEND
EQUIP — Equipment					NEC —		National Electrical
GND — Ground							Code
kcmil — Thousand Circular					TB	—	Terminal Block
	Mils
	Fig. 11 — Field Power Wiring Connections
			THERMOSTAT ASSEMBLY
	REMOVABLE JUMPER
	RH RC	Y1		Y2	W1	W2		G	C	L	X
	R	Y1		Y2	W1	W2		G	C		X
	RED		BLU	PNK	ORN		VIO	BLK	BRN		WHT

UNIT LOW-VOLTAGE CONNECTIONS

Fig. 12 — Field Control Thermostat Wiring

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