3-Phase & 1-Phase Electrical Distribution Wiring Installation in Home
Table of Contents
- 1 What is Three Phase & Single Phase Power?
- 2 Why We Need Three Phase Power Supply?
- 3 Requirements for Three Phase Wring Installation
- 4 How to Wire There Phase Main Distribution Board?
- 5 Wiring Color Codes of IEC and NEC
- 6 How to Connect Single Phase & Three Phase Loads in a Three Phase Wiring Distribution System?
- 7 General Precautions
In our today electrical wiring installation tutorial, we will show how to do a Three Phase Consumer Unit Installation from Utility Pole to a 3-Phase Energy Meter & 3-Phase Distribution board and then How to connect Single Phase & Three Phase Loads in a Three Phase Wiring Distribution System in home electric supply system.
Related Wiring Tutorials:
- Three-Phase Electrical Wiring installation in a Multi-Story Building
- Single-Phase Electrical Wiring installation in a Multi-Story Building
What is Three Phase & Single Phase Power?
In power generation plants, Three Phase power is generator by electrical generator or alternator. In an alternator, the generated voltage and current by three independent coils in stator are apart by 120 degree from each other. The generated power from alternators then transmitted and distributed through transmission and distribution lines to the sub distribution.
In industrial and commercial buildings, they need high power. So they are connected to the three phase Delta connection(3 Phase – 3 Wire System – No Neutral Wire) before distribution transformer and then manage the required voltage and current according to their needs in three phase and single phase supply.
On the other hands, buildings that need high power in three phase and single phase, they are connected to the secondary of distribution transformer. This way, they get three phase Star connection (3-Phase, 4 Wire System with Neutral Wire). In the Star connection, Three Phase Line to Line (Phase to Phase) voltage are 415V AC (in US, 208V) and Single Phase Line to Neutral (Phase to Neutral), there are 230V AC (120V in US).
In Three Phase Supply, motors and large electric heaters can be directly connected to the Three Phases while in in Single Phase, load (Light, fan etc) can be connected in between Phase and Neutral through proper protective devices.
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Why We Need Three Phase Power Supply?
To operate high power equipment and appliances such as electric motors and and high power rated air compressor etc, we need Three Phase Power supply instead of Single Phase Power supply. In ordinary homes, we mostly use Single Phase power supply to operate lighting load, fans, washing machines etc, but in some cases as well as industries offices high torque motors, multi-storey & large buildings, Three Phase power supply needs to operate and maintain the system.
In our previous posts, We did it for Single Phase elctrical wiring installation in home and already know that what are MDB, DB, Final Sub Circuit, MCB, MCCB, CB and RCD etc.
Requirements for Three Phase Wring Installation
In this tutorial, we need the following wiring accessories to wire three phase power in home.
- Three Phase Energy meter 1 No
- Three Pole MCCB, 63A, 1 No
- Double Pole, 63A, 30mA Trip Current RCD, 3 Nos
- Double Pole MCBs, 63A, 3 Nos
- Single Pole, 20A, MCB, 6 Nos
- Single Pole, 16A, MCB, 3 Nos
- Single Pole, 10A, MCB, 6 Nos
- Distribution board cases, 3 Nos
- Bus bar Link for Neutral Cable Connections
- Copper strips for MCB common connection, 3 Nos (Cu Busbar segment)
- Copper strip Busbar for Earth & Ground Link
How to Wire There Phase Main Distribution Board?
Generally, Electric supply and service providers install a single phase energy meter when load is less than 7.5kW (10HP) in domestic areas (consumer unit for home). If the limit is exceeded, then it’s recommended to install a 3-phase energy meter for consumer units. when load is exceeds from 7.5 kW, then 3-phase electrical wiring is recommended in domestic areas (homes).
In this tutorial, We assume that we will only connect single phase load (Light points, fans, TV, Power Socket, AC etc.) in this three phase electrical wiring installation. In other words, we will not power up 3 phase motors because in our homes, we haven’t that kind of (three phase) loads. If three phase load exists in your home, then you can do so. As we can see that the total load is exceeded the limit of single phase electrical wiring installation as we will be feeding different rooms and areas in home, that’s why we have to wire our distribution in three phase system.
Practical Procedure of Three Phase wiring of distribution board & installation
We have learned the basic electrical wiring of bulb, fans etc (i.e. Sub-circuits and final sub circuits) in our previous posts, so follow the steps below to do the same as mention below..
- First of all, connect the three-phase energy meter as shown in fig. ( if you don’t sure that how to wire a 3-phase energy meter, then check this simple tutorial which show How to wire a Three-Phase Energy Meter.
- Connect the MCCB (Moulded Case circuit Breaker) as main switch to the incoming three phases (R, Y, B) from 3-phase energy meter. (Check the wiring color code for different areas in below section)
- Now connect the outgoing three phases (R, Y, B) from MCCB (Moulded Case circuit Breaker) to the DP (Double Pole MCB , RCD, SP (Single Pole MCBs and load) as shown in fig)
- Now connect the RCD from DP with Phase (Line) and Related Neutral Link. The Out going Phase lines should be connected to the final and final sub circuits. The same can be done for Neutral Wires.
- Finally, Connect the electrical appliances with the Earth link terminal which leads to earth electrode in the earthing and grounding system as shown in fig below.
- Do the the same steps for all three distribution boards for different rooms and areas.
Good to Know
You may also use a Four Pole MCCB instead of Three Pole MCCB. Simply connect the Neutral wire in the last slot of that MCCB (Incoming and Outgoing like other phases) and then connect the outgoing Neutral to copper strip (i.e. Earth Link) as shown in fig.
Wiring Diagram of Three Phase Distribution Board
Click image to enlarge
Wiring Color Codes of IEC and NEC
Wiring Color Code: We have used Red for Live or Phase , Black for Neutral and Green for Earth Wire. You may use the specific area codes i.e. IEC – International Electrotechnical Commission (UK, EU etc) or NEC (National Electrical Code [US & Canada] where; NEC: Single Phase 120V AC: Black = Phase or Line, White = Neutral and Green/Yellow = Earth Conductor Three Phase 208 AC: Black = Phase 1 or Line1, Red= Line 2, Blue= Line 3, White / Gray = Neutral and Green/Yellow = Earth Conductor IEC: Single Phase 230V AC: Brown= Phase or Line, Blue= Neutral and Green = Earth Conductor Three Phase 208 AC: Grey= Phase 1 or Line1, Black= Line 2, Brown= Line 3, Blue = Neutral and Green= Earth Conductor
Wiring Color Code:
We have used Red for Live or Phase , Black for Neutral and Green for Earth Wire. You may use the specific area codes i.e. IEC – International Electrotechnical Commission (UK, EU etc) or NEC (National Electrical Code [US & Canada] where;
Single Phase 120V AC:
Black = Phase or Line, White = Neutral and Green/Yellow = Earth Conductor
Three Phase 208 AC:
Black = Phase 1 or Line1, Red= Line 2, Blue= Line 3, White / Gray = Neutral and Green/Yellow = Earth Conductor
Single Phase 230V AC:
Brown= Phase or Line, Blue= Neutral and Green = Earth Conductor
Three Phase 208 AC:
Grey= Phase 1 or Line1, Black= Line 2, Brown= Line 3, Blue = Neutral and Green= Earth Conductor
Below are given the Three Phase Distribution Electrical Wiring Installation Diagram according to NEC & IEC.
Three Phase Electrical Wiring Installation Diagram According to NEC Color Code
Click Image to enlarge
Three Phase Electrical Wiring Installation Diagram According to IEC Color Code
Click image to enlarge
Note: The same description and details can be for both NEC and IEC wiring diagrams used as mentioned for the above general fig 1.
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How to Connect Single Phase & Three Phase Loads in a Three Phase Wiring Distribution System?
As mentioned above, Three Phase loads (415V or 208V AC Such as 3-Phase Motors) can be directly connected to the three lines accordingly i.e. there is no need to connect to the neutral point. For Single Phase Loads (230V or 120V AC Light, TV, Power socket, Fans etc), They can be connected to the Phase and Neutral wire as shown below. Note that Earth or ground wire must be connected to the electrical appliances and equipment connected to both single phase and three phase supply system for safety.
Good to Know
In a Three Phase Wiring Distribution System (Star Connection i.e. 3 Phase, 4 Wire System);
Line to Line Voltage = 415V AC (208V in US)
Line to Neutral Voltage = 230V (120V in US)
- L1 to L2= 440 V
- L2 to L3= 440 V
- L3 to L1= 440 V
- L1 to N = 230 V
- L2 to N = 230 V
- L3 to N = 230 V
in USA and other Countries
- L1 to L2= 208V
- L2 to L3= 208V
- L3 to L1= 208V
- L1 to N = 120V
- L2 to N = 120V
- L3 to N = 120V
- Electricity is Our Enemy, if you give it a chance to kill you, Remember, they will never miss it. Please read all caution and instruction while doing this tutorial in practical.
- Disconnect the power source before servicing, repairing or installing electrical equipments.
- Ue the proper cable in size with this simple calculation method ( How to determine the suitable size of cable for Electrical Wiring Installation)
- Never try to work on electricity without proper guidance and care.
- Work with electricity only in presence of those persons who has good knowledge and practical work and experience who know how to deal with electricity.
- Read all the instruction and cautions and follow them strictly.
- Doing your own electrical work is dangerous as well as illegal in some areas.Contact the licensed electrician or the power supply company before practicing any change in electrical wiring connection.
- The author will not be liable for any losses, injuries, or damages from the display or use of this information or if you try any circuit in wrong format. So please! Be careful because it’s all about electricity and electricity is too dangerous.
You may also check the related Electrical Wiring Installation Tutorials.
- How to Wire Wire a Distribution Board [Single Phase]
- How to Wire a Distribution Board with RCD – Single Phase – (from Energy Meter to the Consumer Unit)
- Three Phase Electrical Wiring Installation Tutorials
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