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Three Phase Electrical Wiring Installation in Home

3-Phase Electrical Wiring Installation at Home

3-Phase Consumer Unit Installation from Utility Pole to 3-Phase Energy Meter & 3-Phase Distribution board and How to Connect Single Phase & Three Phase Loads in a Three Phase Wiring Distribution System
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
Cupper strips for MCB Common connection, 3 Nos
Generally, Electric company installs Single phase energy meter for less than 7.5kW (10HP) load in domestic areas (consumer unit for home). If the limit is exceeded, then it’s recommended that install a 3-phaseenergy meter for Consumer units, when load is exceeds from 7.5 kW, then 3-phase electrical wiring is recommended in domestic areas (Homes)
We assume that we will only connect single phase load (Light points, fans, TV, 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 so. As we can see that the total load is exceeded the limit of single phase electrical wiring installation, that’s why we have to wire our distribution in three phase system.
Practical Procedure of Three Phase wiring of distribution board & installation
 As we have learned the basic electrical wiring of bulb, fans etc (i.e. Sub-circuits and final sub circuits)
  • 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 method. 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
  • Now connect the outgoing 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)
  • Also connect the Neutral wires to RCDs and then to neutral links and then to specific loads (as shown in fig).
 Click image to enlarge Three Phase Electrical Wiring
Good to Know
You can also use a Four Pole MCCB instead of Three Pole MCCB. But you should connect the neutral in the last slot of that MCCB (Incoming and Outgoing like other phases) and then connect the outgoing neutral to cupper strip as shown in fig.
How to Connect Single Phase & Three Phase Loads in a Three Phase Wiring Distribution System
In the above 3-phase wiring system, load can be connected by this way
  Click image to enlarge Three Phase Elecrtrical Wiring Installation
Good to Know
In a Three Phase Wiring Distribution System;
Line to Line Voltage = 440V
Line to NeutralVoltage = 230V
L1 to L2= 440V
L2 to L3= 440V
L3 to L1= 440 V
L1 to N = 230V
L2 to N = 230V
L3 to N = 230 V

in USA and other Countries

L1 to L2= 208V
L2 to L3= 208V
L3 to L1= 208 V
L1 to N = 120V
L2 to N = 120V

L3 to N = 120 V

 General Precaution
  • Disconnect the power source before servicing, repairing or installing electrical equipments and installation.
  • Also use 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 to deal with electricity
  • Read all instruction and cautions and follow them strictly.
  • The author will not be liable for any losses, injuries, or damages from the display or use of this information or try any circuit in wrong format so please! Be careful because it’s all about electricity and electricity is too dangerous

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  2. can we use tpn mccb in place of 3p mccb?

  3. i am iti electrician 7year house wiring and eascalator maintance .i am othar works intrusted my no 09004396906

  4. Pradeep Mukund Nawar

    I would like to convert phase 1 to phase commercial

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  13. Thanks, very useful information

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  18. In the diagram, no protection (switchgear) is used between utility pole and incoming of 3-ph energy meter…is direct connection from utility pole to meter OK or is it necessary to use any fuse/cut??

  19. Thanks. The information is very useful since I am constructing my own 4 bedroom house in New Delhi. I have a query though: i would like to have one light; fan and TV in each room to be connected to a single phase UPS. The electrical contractor is asking for high extra payment for doing this. Would there be significant extra cost involved. I would have thought that the only extra is drawing one wire from the mains to the UPS and from the ups to the bus for emergency circuits. The wiring of the mergency circuits would not change since they would get power from the grid normally and from the ups in case of power failure

  20. I would like to have more of your enlightening articles via my email. Also, you can send me any of your publication to James Mwaura Kinyanjui, P.O. Box 62351-00200, City Square, Nairobi, Kenya. Country code +254

    Thank You

  21. One ups power and multi utility meters wiring diagrams

  22. I want to 3,phase and single phase electrical panel energy meter CIRCUIT

  23. Abdul quadri Ismail adio

    Are you a technical practice or master electricity cause its a dangerous, although in your country your current their may not over 110 by that you’re free

  24. what cause circuit breaker to read 439v and trips most of the time

  25. I need rotary switch connection pls send to mail id pavikpn007@gmail.com

  26. Im really impressed from your work.

    Please can you guide or send me a link to understand a change over switch and a phase selector in a 3 phase environment.

  27. Consider a max 10 KW connection is provided by electricity board then what will be max power capacity at each phase?

    Total Power : 10 KW
    Electricity Board : MAHA VITARAN

    Phase 1(R) : V = ? & I = ?
    Phase 2(Y) : V = ? & I = ?
    Phase 3(B) : V = ? & I = ?

  28. we ask some question the building the install wiring is three phase but the wiring is single phase that building have a laboratory so i think some lab need 3 phase for the units so how to install 3 phase electrical wiring , the electric compony install 25 kva its that enough for the load of the building.

  29. I can not understand how Phase to Phase voltage is 440 volt , and phase to neutral voltage is 230 v ?
    as i know V phase to neutral = VLine/ root 3

    so for 440v VL , V phase = 254 volt ?

    please correct if I am wrong

  30. 25hp motor can you use 220v contactor?

  31. Easy to follow description for Electrical Professionals and even other engineering fields.

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