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Air ConditioningAir Conditioning

Three Phase PowerThree Phase Power

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Three Phase PowerThree Phase Power

• Most common in commercial and industrial buildings

• Three hot legs, one ground, and one neutral

• L1, L2, L3, N, and Ground

• Most common in commercial and industrial buildings

• Three hot legs, one ground, and one neutral

• L1, L2, L3, N, and Ground

3Two types of transformer hook ups

Delta(OLD) Wye(NEW)

Two types of transformer hook ups

Delta(OLD) Wye(NEW)

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208 Volt 208 Volt

• Three basic types of three phase power that you may encounter– 208V-3 phase-60Hz (Wye)– 240V-3 phase-60Hz (Delta)– 480V-3 phase-60Hz (Wye)

• Three basic types of three phase power that you may encounter– 208V-3 phase-60Hz (Wye)– 240V-3 phase-60Hz (Delta)– 480V-3 phase-60Hz (Wye)

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208V-3 phase-60Hz (Wye)208V-3 phase-60Hz (Wye)

• Common in newer commercial buildings that require three phase power for large equipment, but also need many 120 volt circuits.

• Common in newer commercial buildings that require three phase power for large equipment, but also need many 120 volt circuits.

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• Power Configuration – 208V 3 Phase– 208V Single Phase – 120V Single Phase

• For single phase power use 2 leads – 2 Hot legs (208V)– One hot leg and neutral (120V)

• Power Configuration – 208V 3 Phase– 208V Single Phase – 120V Single Phase

• For single phase power use 2 leads – 2 Hot legs (208V)– One hot leg and neutral (120V)

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480V-3 phase-60Hz (Wye)480V-3 phase-60Hz (Wye)• Common in industrial buildings

where high voltage is desirable, large amounts of fluorescent lighting (277V) are needed, and minimal 120 volt circuits are needed.

• Common in industrial buildings where high voltage is desirable, large amounts of fluorescent lighting (277V) are needed, and minimal 120 volt circuits are needed.

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• Examples of equipment used in HVAC:– Evaporator fans – Compressor– Condenser fans (277V)

• Examples of equipment used in HVAC:– Evaporator fans – Compressor– Condenser fans (277V)

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• Power Configurations– 480V three Phase – 277V single Phase* Separate transformer in

building needed to supply 120 volt power.

• Power Configurations– 480V three Phase – 277V single Phase* Separate transformer in

building needed to supply 120 volt power.

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240V-3 phase-60Hz (Delta)

240V-3 phase-60Hz (Delta)• Found in older commercial and industrial buildings

• Contains one high leg or wild leg • The wild leg should always be

phase B in the panel • Center leg or wild leg should be

orange• Do a safety check first

• Found in older commercial and industrial buildings

• Contains one high leg or wild leg • The wild leg should always be

phase B in the panel • Center leg or wild leg should be

orange• Do a safety check first

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• Care must be taken between wild leg and neutral– Wild leg to neutral is 180V-200V– Not usable voltage – Should be identified orange.

• Always check with your volt meter when working on any three phase system

• Each leg to neutral or ground

• Care must be taken between wild leg and neutral– Wild leg to neutral is 180V-200V– Not usable voltage – Should be identified orange.

• Always check with your volt meter when working on any three phase system

• Each leg to neutral or ground

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