Electrical Service Types and Voltages

This page describes various types of utility electrical services and supply voltages. The nominal system supply voltages listed below can vary by ±10% or more. WattNode® meter models are available in seven different versions that cover the full range of electrical services types and voltages. Meters and current transformers are designed for use on either 50 or 60 Hz systems.

Classification of Electrical Services


Alternating current electric power distribution systems can be classified by the following properties:

Wye Line-to-Neutral
Wye or Delta Line-to-Line
120 208
120 240
230 400
240 415
277 480
347 600

Common Electrical Services & Loads

Single Phase Three Wire

Single Phase Three Wire Electrical Service

Also known as an Edison system, split-phase or center-tapped neutral. This is the most common residential service in North America. Line 1 to neutral and Line 2 to neutral are used to power 120 volt lighting and plug loads. Line 1 to Line 2 is used to power 240 volt single phase loads such as a water heater, electric range, or air conditioner.

Three Phase Four Wire Wye

Three Phase Four Wire Wye Electrical Service

The most common commercial building electric service in North America is 120/208 volt wye, which is used to power 120 volt plug loads, lighting, and smaller HVAC systems. In larger facilities the voltage is 277/480 volt and used to power single phase 277 volt lighting and larger HVAC loads. In western Canada 347/600V is common.

Three Phase Three Wire Delta

Three Phase Three Wire Delta Electrical Service

Used primarily in industrial facilities to provide power for three-phase motor loads, and in utility power distribution applications. Nominal service voltages of 240, 400, 480, 600, and higher are typical.

Uncommon Electrical Services

Three Phase Four Wire Delta

Three Phase Four Wire Delta Electrical Service

Also known as a high-leg or wild-leg delta system. Used in older manufacturing facilities with mostly three-phase motor loads and some 120 volt single-phase lighting and plug loads. Similar to the Three Phase Three Wire Delta discussed above but with a center-tap on one of the transformer winding to create neutral for 120 volt single-phase loads. Motors are connected to phase A, B, and C, while single-phase loads are connected to either phase A or C and to neutral. Phase B, the high or wild leg, is not used as the voltage to neutral is 208 volt.

Three Phase Two Wire Corner-Grounded Delta

Three Phase Two Wire Corner-Grounded Delta Electrical Service

Used to reduce wiring costs by using a service cable with only two insulated conductors rather then the three insulated conductors used in a convention three phase service entrance.

International Electrical Distribution Systems

Description L–N
Countries WattNode Models
(Wye or Delta–Voltage)
1-Phase, 2-Wire 120 V with neutral 120 US 3Y-208
1-Phase, 2-Wire 230 V with neutral 230 EU, Others 3Y-400
1-Phase, 2-Wire 208 V (No neutral) 208 US 3D-240
1-Phase, 2-Wire 240 V (No neutral) 240 US 3D-240
1-Phase, 3-Wire 120/240 V 120 240 US 3Y-208
3-Phase, 3-Wire 208 V Delta (No neutral) 208 US 3D-240
3-Phase, 3-Wire 230 V Delta (No neutral) 230 Norway 3D-240
3-Phase, 3-Wire 400 V Delta (No neutral) 400 EU, Others 3D-400
3-Phase, 3-Wire 480 V Delta (No neutral) 480 US 3D-480
3-Phase, 3-Wire 600 V Delta (No neutral) 600 US, Canada none1
3-Phase, 4-Wire 208Y/120 V 120 208 US 3Y-208, 3D-240
3-Phase, 4-Wire 400Y/230 V 230 400 EU, Others 3Y-400, 3D-400
3-Phase, 4-Wire 415Y/240 V 230 415 Australia 3Y-400, 3D-400
3-Phase, 4-Wire 480Y/277 V 277 480 US 3Y-480, 3D-480
3-Phase, 4-Wire 600Y/347 V 347 600 US, Canada 3Y-600
3-Phase 4-Wire Delta 120/208/240
Wild Phase
240 US 3D-240
3-Phase 4-Wire Delta 240/415/480
Wild Phase
480 US 3D-480
3-Phase Corner-rounded Delta 208/240 240 US 3D-240
3-Phase Corner-Grounded Delta 415/480 480 US 3D-480


See Also


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