Three-Phase Electrical Wiring Installation in Multi-Story Buildings

Three-Phase Electrical Wiring Installation in Multi-Story Buildings . When it comes to powering a multi-story building, efficiency, reliability, and safety are critical. One of the most effective solutions for such scenarios is the three-phase electrical wiring system. Known for its robust design, it ensures uninterrupted power distribution, accommodating the high energy demands of modern buildings.

This comprehensive guide explores the essentials of three-phase wiring installation, covering design principles, safety measures, and practical installation steps.

What is a Three Phase Electrical System?

A three-phase system is an advanced electrical setup where three alternating currents of equal frequency and amplitude flow at 120-degree phase intervals. This setup is widely used in commercial and industrial applications, ensuring:

Balanced power loads.
Reduced energy losses.
Enhanced efficiency in power transmission.

Read More : How to Wire a Three-Phase Meter?

Benefits of Three Phase Wiring in Multi-Story Buildings

Enhanced Power Distribution

Three-phase systems distribute electrical loads evenly across phases, minimizing risks of overload. This is particularly important in multi-story buildings where elevators, HVAC systems, and lighting require high power.

Cost Efficiency and Reliability

While the initial investment may be higher, the operational efficiency of three-phase systems translates to long-term savings. Components such as motors run more smoothly and consume less energy compared to single-phase systems.

3-phase-wiring-instillation-in-multi-story-building-diagram

Requirements for Three Phase Wring Installation in Multistory Building

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

Designing a Three Phase Wiring System

Load Calculations and Power Requirements

Accurately calculating the total load requirements is critical to avoid overloading. Factors like equipment type, power rating, and future scalability are considered.

Safety Standards and Compliance

Compliance with local and international electrical codes ensures both safety and legality. Standards like the IEC 60364 provide guidelines for system design and installation.

Blueprints and Layout Planning

A detailed blueprint highlights the placement of conduits, panels, and connection points, ensuring a seamless installation process.

How to Wire There Phase Main Distribution Board in Multistory Building?

We have shown 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..

To do electric distribution system in a multi-storey building, follow the following steps.

First of all, connect the three-phase energy meter as shown in fig. ( if you aren’t sure that how to wire a three-phase energy meter, then check this simple tutorial which show How to wire a Three-Phase Energy Meter?
Connect the Moulded Case circuit Breaker (MCCB) as main switch to the incoming three phases (R, Y, B) from three-phase energy meter. (Check the wiring color code for IEC and NEC in below section)
Now connect the outgoing three phases (R, Y, B) from moulded case circuit breaker (MCCB) to the double pole (DP) 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 circuits and final sub circuits. The same can be done for Neutral Wires.
Finally, Connect the electrical devices and appliances with the Earth link terminal which leads to earth electrode in the earthing and grounding system as shown in fig.
Do the the same steps for all three distribution boards in different storey (Three storeys in our case).

Keep in mind that you have to use the main breaker with proper rating i.e. which carry the total load current of all distribution boards of each storey and use the breaker in sub distribution board according to the load of that desired storey i.e. fans, lights etc in single storey and so on for other storeys. Also, You may use a 4-Pole MCCB instead of 3-Pole MCCB as the last 4th slot can be used to connected the Neutral Wire (Check the diagram and brochure for proper guidance).

Also, use separate main breaker for each storey and then distribute wiring in additional three or four main circuits in different sections. If you directly connect the over all load of different storys to the main breaker instead of separate main board, all the connected load (bulbs, fans etc) would disconnect in the whole building at once in case of tripping any circuit due to some reason (short circuit etc) which leads to trip the main switch.

In addition, In case of single circuit instead of three circuits, if the load of a single storey increases, the more current will have to flow and cables may be overheated. Also, voltage drop would be increased so the rated voltage may not reach to the electrical appliances. In that case, the connected light bulbs would be dimmer and other appliances may not work properly. Moreover, there is a risk of electric fire and hazard in the building due to overheated cables.

Three-Phase-Electrical-Wiring-Installation-in-a-Multi-Story-Building

Installation Process of Three Phase Wiring

Step 1: Preparing the Infrastructure

Start by inspecting the building’s infrastructure to determine the placement of conduits, switchboards, and circuit breakers.

Step 2: Installing Conduits and Trunking Systems

Install conduits or trunking systems for cable routing. This prevents external damage and keeps cables organized.

Step 3: Wiring and Connection Procedures

Connect cables to their respective bus bars and circuit breakers.
Ensure connections are secure and insulated to prevent energy leaks.

Step 4: Testing and Commissioning

Conduct tests like insulation resistance, continuity checks, and load testing to confirm the system is functional and safe.

Three-Phase Electrical Wiring Installation in Multi-Story Buildings

Electrical 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

Read More : Three-Phase Electrical Power

Wiring Diagram of Three Phase Distribution Board In Multi-Storey Building

Electrical-Wiring-Diagram-of-Three-Phase-Single-Phase-Consumer-Unit-with-RCD

Maintenance and Troubleshooting of Three Phase Systems

Periodic Inspections

Schedule regular inspections to check for overheating, loose connections, or wear and tear in components.

Diagnosing Common Issues

Use tools like multimeters and thermal cameras to diagnose issues like phase loss, overheating, or voltage fluctuations.

Frequently Asked Questions

What is the difference between single-phase and three-phase?

Single-phase systems are suitable for residential purposes, handling lower power loads. Three-phase systems are ideal for commercial applications, offering higher efficiency and power capacity.

How much power can a three-phase system handle?

The power capacity depends on the voltage and current ratings of the system. For instance, a 400V three-phase system can handle significantly higher loads than a 230V single-phase system.

Is it more expensive to install a three-phase system?

Yes, the upfront cost is higher, but the efficiency and long-term savings make it a cost-effective choice for multi-story buildings.