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Single-Phase Electrical Wiring installation in a Multi-Story Building

Single-Phase Electrical Wiring installation in a Multi-Story Building

Multistory building Distribution System
  • Three Phase Energy meter 1 No
  • Two Pole MCCB, 100A, 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

Step by Step Procedure

To do Electric wiring distribution system in a multi-storey building, follow the following steps.
As we have leaned the basic electrical wiring of bulb, fans etc (i.e. Sub-circuits and final sub circuits) so,
  1. First of all, connect the single-phase energy meter as shown in fig. (If you don’t sure that how to wire a 1-phase energy meter, then check this simple method How To Wire a Single Phase kWh meter ( Digital or analog Energy Meter)
  2. Connect the MCCB (Moulded Case circuit Breaker) as a two pole main switch to the incoming Phase and Neutral (P and N)) from 1-phase energy meter
  3. Now connect the outgoing Phase and Neutral (P and N) from MCCB (Moulded Case circuit Breaker) to the DP (Double Pole MCB , RCD, SP (Single Pole MCBs and load) of each storey, as shown in fig)
  4. Also connect the Neutral wires to RCDs and then to neutral links and then to specific loads (as shown in fig).
  5. Do not forget about earthling. So connect all loads with Earth link and earth link must be connected to the earth electrode viva earth lead (as shown in fig)
  6. Use the main breaker with proper rating i.e. which carry the total load current of all distribution boards of each storey but install the breaker in Sub distribution board according to that desired storey i.e. fans, lights etc in one storey and so on for other storey.
Click image to enlarge
 1-Phase Electrical Wiring installation in a Multi-Story Building

Good to Know
In a Single Phase Wiring Distribution System;
Line to Neutral Voltage = 230V
L to N = 230V  
In USA and other Countries…
L to N = 120V
Distribute Electrical wiring of each storey in three or four circuits. The purpose of this,
  1. If a circuit breakerof a circuit or distribution board trip due to some reason, then all bulb and loads would not disconnect at once.
  2. In case of one circuit instead of three circuits, if the load of storey increases, then more current will flow and cables may overheat. Also voltage drop would be increased. So rated voltage may not reach to electrical appliances,therefore, the light of bulbs would be dimmed. Moreover, due to overheat in the cables, there is also a risk of fire in the building.
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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  1. very help ful….

  2. really helpful, especially the diagram.

  3. oooops iam help full

  4. Thanks this was the best electrical article i have ever come across, Damm good

  5. It is very helpful to the electrical practitioner…

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