How to wire a DB – Distribution Board Wiring

Distribution Board or DB is an electricity supply system or a common enclosure that distributes the electrical power feed into subcircuits. It includes isolator, RCCB (Residual current circuit breaker) or RCD (Residual-current device) devices, protective fuses or MCB’s (Miniature Circuit Breaker) for each subcircuit, etc.

The Phase and Neutral supply lines (230V AC 50Hz/60Hz) are fed to the DB through the service drop running from the utility pole. It is then connected to the energy meter through a fuse.

The phase and neutral lines from the energy meter are connected to the main isolator. The isolator is used to OPEN and CLOSE the lines manually, which is the main switch of the electrical system.


The phase and neutral lines from the isolator are then connected to the RCCB. The RCCB is a device used to protect from current leakage. It isolates the circuit during fault conditions due to current leakage as well as during earthing, electric shock; when somebody comes to contact with phase and earth.

DB wiring diagram, distribution board wiring diagram

From RCCB the Neutral lines are connected to the neutral link. And the phase lines are connected parallel to MCB’s. The MCB is used to protect from overcurrent resulted due to overload or short circuit. It isolates the phase line if the current exceeds its maximum limit. Both MCB and RCCB can be turned off manually to isolate the line.

Refer: MCB, RCCB basic differences

Through the MCB phase lines are distributed to electrical wiring for lighting, fixed devices, and power distribution points. This type of arrangement is the commonly used method of distribution board for house wiring.

The cable or wire size, the rating of breakers, fuse, etc depends on the type of wiring, purpose, and rating of loads. It should be properly selected as per the recommended standards and safety requirements.

The neutral and earth lines are distributed to the subcircuits through the neutral link and earth link respectively. The earth line running from the earth link is connected to the earth pit with an earth rod. Earthing is very essential for the protection of the electrical system, so it should be ensured that the earthing is proper.

Refer: What is the importance of Earthing?

15 Responses

  1. Ahmad says:

    Thanks for sharing this good and benefit ideas.

  2. Ioron says:

    Nice one.
    Job well done sir

  3. Franklin says:

    Thankyou I get knowledge

  4. Lubangakene Cedric says:

    Wow wounderfull

  5. aumit kumar sarker says:

    Thanks for the diagram that contain a clear idea.

  6. Micheal says:

    If I’m connected to db in my cottage if the main house doesn’t have credit units I’m still be able to use electric? C

  7. isah says:

    i really appreciate it is very good for engineers

  8. Phinius Murithi says:

    thanks for good work & support

  9. Vikas C Sawant says:

    thank you

  10. Sunusi Mohammed says:

    Thanks nice post

  11. Babar ansari says:

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  12. Answem Saaondo Abel says:

    Good job

  13. Agboba Monday says:

    Good work

  14. Emmanuel Omenaka says:

    This was a succinct explanation of house wiring, Distribution board(breakers) and electrical installation in general.

    Thank you sir.

  15. JOHN says:

    hi there,
    I am an electrician, and I would like the have more knowledge in this field. thank you so much for your information.

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