What are different types of electrical systems?

Author: May

Mar. 07, 2024

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Tags: Automobiles & Motorcycles

It shouldn't come as a surprise to anyone that submeters need to be selected and installed based on the type of electrical system already present in the facility. Submeters and electrical systems can be grouped into either single phase (1ph), two phase (2 ph) or three phases (3ph). The main difference between the two is the voltage that goes through each type of wiring system.

Another difference is in regards to where each type is used. The overwhelming majority of residential homes operate under a single phase or a two-phase system. Commercial buildings, on the other hand, usually have three-phase wiring installed.

Below is a short rundown of each of these electrical systems.

DIFFERENT TYPES OF ELECTRICAL SYSTEMS

SINGLE PHASE

Single phase electrical systems have three wires within the installation. Two of these wires are “hot”, one being the ‘Line’ and the other the ‘Neutral’ while the third one is ground. The voltage between the two hot wires is usually (in North-America) 120 volts. In North America, most appliances use 120 volts, that is why most wall receptacles in homes, offices and public places will be wired with one hot wire and the neutral. These systems are known as single-phase, two wire systems (1-ph, 2w). Common appliances such as light bulbs, fridges, TVs, press irons, etc., have a small enough line load to require a single phase electrical feed.

In single homes, larger appliances like; ranges, dishwashers, some laundry washing machines, clothes dryers, and heaters may also use 240 volts of electricity with two 120 volts lines and one neutral wire. Single phase meters in these cases are characterized by three terminals - two ‘lines’that go in plus one neutral wire, It is what's also known as a split-phase circuit. Regarding wiring, there is one phase and three wires that come to the house from the main power line. These systems are also known as single-phase, three-wire systems (1-ph, 3w)

Two PHASE

Apartments and Condos, usually would use two phases for each unit so they would have two live wires with 208 volts between them and 120 volts between each line and a neutral, allowing the unit to power receptacles and lighting at 120 Volts and the range at 208 volts. These systems are known as two-phase, three wire-systems (2-ph, 3-w).

THREE PHASE

Three phase electrical systems are supplied by four wires, three carrying lines (for example 120 volts each to neutral or 208 Volts line to line) and a neutral one making this system more efficient than a single phase one. All types of machinery that use large motors to operate, including central AC units, pumps, air handling units, garbage compactors, elevators, and snow melting systems run on three phase systems and require three-phase electrical meters. These meters have four terminals in total – three lines going in and fourth being the neutral coming in from the main power supply and into the facility. These systems are known as three-phase, four wire systems (3-ph, 4-w).

In North America the most common three phase voltages are 208 volts in which the line to neutral voltage is (208/1.73= 120 V) 120 volts, and 480 volts which represents line to line with a line to neutral voltage of 277 volts. A one system not so common is 416 Volts with a line to neutral voltage of 240 volts sometimes used in multi-residential buildings.

Canada is unique in the use of 600 Volts distributions systems with a line to neutral voltage of 347 volts. Fortunately for Canadians there are lighting systems and that operate in single phase mode at 347 volts. In this blog we only covered Wye (“Y”) connected systems, in future blogs we will discuss Delta connected distribution systems and different Voltage systems.

UNIVERSAL VOLTAGE INPUT

Having a universal voltage electrical meters is advantageous. That is a single meter that can operate at all these different voltages. This provides the installer with a single model that can literally be installed in any type of low voltage installation, whether residential, commercial or industrial, to the user the flexibility of changing it from one circuit to another at a later date and to the distributor a reduced number of SKU.s for a reduced inventory. As their name would suggest, these meters can accommodate all voltages between 85 and 347 volts. Since these systems encompass the entire spectrum of the low voltage supply, they can also tolerate well voltage disturbances in the lines, current fluctuations and operate on either 50 or 60 Hz.

 

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. The new WattNode Wide-Range Modbus covers 100-600 Vac, wye and delta, single-phase and three-phase with a single model. 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:

  • Frequency: 50 Hz or 60 Hz
  • Number of phases: single or three phase
  • Number of wires: 2, 3, or 4 (not counting the safety ground)
  • Neutral present:
    • Wye connected systems have a neutral
    • Delta connected systems typically do not have a neutral
  • Voltage classes: (ANSI C84.1-2016)
    • Low Voltage: 1000 volts or less
    • Medium Voltage: greater than 1000 volts and less than 100 kV
    • High Voltage: greater than 100 kV and equal to or less than 230 kV
    • Extra-High Voltage: greater than 230 kV but less than 1000 kV
    • Ultra-High Voltage: equal to or greater than 1000 kV

 

Wye Line-to-Neutral Voltage Wye or Delta Line-to-Line Voltage 120 208 1201 240 230 400 240 415 277 480 347 600
  • Line-to-line voltages in three phase systems are typically 1.732 times the phase-to-neutral voltages:
  • In symmetrical three-phase electrical system, the phase-to-neutral voltages should be equal if the load is balanced.
  • Note: 1201 Refers to a three phase four wire delta service.

 

Common Electrical Services & Loads

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  • In the following drawings, the coil symbols represent the secondary winding of a utility service transformer or other step down transformer. Electrical code regulations in most jurisdictions require that the neutral conductor be bonded (connected) to the earth safety ground at the electrical service entrance.

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Single Phase Three Wire

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

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

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.

Download: Electrical Service Types and Voltage (AN-129) (PDF, 3 pages)

Uncommon Electrical Services

Three Phase Four Wire Delta

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

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 Vac L–L Vac 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 240 415 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 120, 208 240 US 3D-240 3-Phase 4-Wire Delta 240/415/480 Wild Phase 240, 415 480 US 3D-480 3-Phase Corner-Grounded Delta 208/240 – 240 US 3D-240 3-Phase Corner-Grounded Delta 415/480 – 480 US 3D-480
  • 1By using potential transformers (PTs), WattNode meters can measure 600 volt delta services as well as medium and high voltage services.

Questions

  • Do 3Y-600 and 3D-600 appear in the US or only in Canada?
    • Yes, wye and delta 600 volt services are used in both countries but in the US they are less common.
  • What services are used in Canada?
    • Mostly 208Y/120 volt and 600Y/347 volt wye services and occasionally 600 volt delta too.

 

See Also

What are different types of electrical systems?

Electrical Service Types and Voltages

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