Single Phase Distribution Box (DB) Wiring Diagram and Connection

Hey, in this article we are going to see the Single Phase Distribution Box Wiring Diagram and Connection Procedure. A distribution board or distribution box is where the main power supply is distributed to multiple loads. And all the switching and protective devices are installed in the distribution box.

Single Phase Distribution Box generally consists of Double Pole MCBs, Single Pole MCBs, and RCCBs. Single-phase distribution boards are mostly used in domestic house wirings such as houses offices, shops, etc. In India, a 230V single-phase AC supply is used for domestic so here all the devices used in the DB is operating with a 230V AC supply whereas in USA 110 or 120V AC supply is used for domestic loads so here all the devices used in the DB is operating with 110V or 120V AC supply.

 

Single Phase Distribution Box (DB) Wiring Diagram

Here, you can see the wiring diagram of the 230V single-phase distribution box wiring diagram.

Devices used in the DB

MCB(Miniature Circuit Breaker)

Here, a double pole MCB is used as the Main MCB or Main switch. It has the highest capacity than other MCBs used in the DB. Generally, 63A MCB is used as the main switch in most of the domestic installations. The single input supply(phase and neutral) is connected to this main MCB. When this MCB is turned on all other MCBs will get the power supply.

Generally, a 2-pole MCB is used as the main switch. Single-pole MCBs are used for the output loads. For special loads sometimes double pole MCBs are used for output loads.

RCCB(Residual Current Circuit Breaker)

RCCB is a very important protective device and it must be used in domestic installations. RCCB can give protection against electrical shock, leakage current fault, insulation failure, etc. The operating current rating of the RCCB should be the same as the Main MCB. Generally, 30mA sensing current-rated RCCBs are used for single-phase domestic installations. The output of the Main MCB is to be connected to the input of the RCCB and the output of the RCCB is to be connected to the output MCBs.

Neutral Link

A neutral link is used to distribute a neutral supply to all the output loads. When single-pole MCBs are used for output loads, the neutral wire of the loads is connected to the neutral link.

Earth Link

The earthing terminal of the power supply and loads are connected to the earth link. Sometimes the wire from the earthing pit is also directly connected to the earth link. Even the metallic body of the distribution panel is also connected to the earth link.

Single Phase Distribution Box (DB) Connection Procedure

1. Take the appropriate rating of MCB and RCCB as per your load requirements. Identify the Input and Output sides of the MCBs and RCCBs.
2. Connect the phase and neutral wires from the input power supply to the input of the Main MCB.
3. Connect the output of the Main MCB to the input of the RCCB.
4. If you use a DP MCB for output load then connect both phase and neutral from the output of the RCCB to the input of the Load MCB.
5. If you use single pole MCBs then connect only phase wire from the output of the RCCB to the inputs of the single pole load MCB.
6. Connect the neutral wire from the output of the RCCB to the Neutral Link.
7. Connect the earth wire to the earth link. The earth wire may come from the power supply cable or earth pit.
8. Connect the both phase and neutral terminal of the load(which you want to connect with DP MCB) to the output of the DP MCB, and the earth wire to the Earth link.
9. Connect the phase terminal of the load (which you want to connect with SP MCB) to the output of the SP MCB. And connect the neutral and earth wire to the neutral link and earth link respectively.

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