How to Troubleshoot 3-Phase Power Systems in Older Commercial Buildings

How to Troubleshoot 3-Phase Power Systems in Older Commercial Buildings


Troubleshooting electrical issues in older commercial buildings with 3-phase power systems can be challenging. However, with some background knowledge of how these systems work, a systematic approach, and the right tools, any technician can efficiently track down problems and restore power. In this article, I will provide an in-depth guide on troubleshooting 3-phase power in older commercial buildings.

How 3-Phase Power Systems Work

To troubleshoot 3-phase systems effectively, you need to understand some basics of how they operate.

Gather Information on the Electrical System

Before troubleshooting, gather as much information as possible about the 3-phase system:

Safety Precautions

Always follow safety procedures when working on 3-phase systems:

Troubleshooting Steps

With background knowledge and safety preparations complete, follow these general steps to troubleshoot:

1. Clearly Define the Problem

2. Review One-Line Diagram

3. Check Fuses/Breakers

4. Check Voltages

5. Isolate Malfunctioning Loads

6. Check Connections

7. Check Conductors

8. Start Restoring Power

When to Call an Electrician

If the issue is beyond your skill level to resolve, call a qualified electrician. Some examples:

An experienced electrician can use more advanced troubleshooting tools to identify issues. They also have training to work on systems safely while energized. Calling early saves time and prevents damage if the problem worsens.


Troubleshooting 3-phase systems follows a logical progression - gathering information, safety preparations, isolating the problem through voltage checks and visual inspection, and finally restoring power. While complex, any technician can resolve common issues systematically. Know when the problem requires an expert electrician, and don't hesitate to call them. With this approach, you can efficiently restore power and prevent prolonged downtime in older commercial buildings.