How to Troubleshoot Rare Electrical Faults in Commercial Buildings

How to Troubleshoot Rare Electrical Faults in Commercial Buildings

Troubleshooting electrical faults in commercial buildings can be challenging, especially when dealing with rare or intermittent issues. As a commercial electrician, mastering this skill requires patience, diligence, and the right tools and knowledge. In this guide, I will walk through the step-by-step process I use to track down even the most elusive electrical gremlins.

Gather Information from Tenants

The first step is always to interview the tenants experiencing the problem. Oftentimes, they can provide clues that narrow down where the issue originates.

Thorough tenant interviews provide vital clues that can shortcut the troubleshooting process. The key is asking the right questions.

Consult the Blueprints

After tenant interviews, I review the building electrical blueprints. Knowing exactly how the electrical system is designed and what equipment is installed where is crucial when chasing down elusive faults.

Key things I look for in the prints:

Thoroughly understanding the electrical distribution helps me develop a mental map of where to begin testing. I mark up my copy of the prints during troubleshooting to document test results.

Conduct Initial Voltage Measurements

Before getting into intensive testing, I take baseline voltage measurements throughout the building:

I use a true RMS multimeter for accurate readings of RMS voltage and current. On electronic loads, a normal DMM can provide false readings.

This high-level voltage survey reveals if the issue stems from poor power coming into the building, a distribution problem within panels, or a more localized fault affecting only certain loads. It helps guide the next steps of my investigation.

Inspect Connections, Components, and Conductors

Now the meticulous, methodical work begins - visually inspecting every part of the electrical system from the utility service to outlets and light fixtures. I focus on:

Open Electrical Enclosures

Conductors and Cabling

Light Fixtures and Receptacles

I open every junction box and inspect the integrity of conductors and splices. It's tedious work, but necessary to find elusive electrical bugs.

Use Diagnostic Equipment

Visual inspections provide part of the picture. To gain more insight, I use:

For complex intermittent problems, I may need to monitor over days or weeks with dataloggers to capture an elusive fault occurring randomly.

Isolate the Problem Area

After thorough inspections and testing, I should have a decent idea of the problem's general location. Time to isolate it further.

Shut down sections of circuits and see if the issue disappears. This narrows it down to a specific branch or piece of equipment.

Disconnect certain loads like large motors. If the problem goes away, focus there.

Check readings upstream and downstream to bracket the problem between two points.

Review findings to look for patterns and correlations between the time the issue occurs and certain equipment operating. This can lead straight to the culprit.

Sometimes I have to get creative and set up test equipment to monitor over time. The goal is to incrementally chip away at the area affected until the source is found.

Pinpoint the Exact Fault

When the problem is narrowed down to a specific circuit or device, I drill down to find the exact failing component.

Meticulous voltage, resistance and continuity checks will ultimately lead to the defective part. I focus testing there until the smoking gun is found.

Implement Repairs and Confirm Normal Operation

When the specific fault is identified, it's time to implement repairs:

After repairs, I power up the system and load test it thoroughly to confirm normal functioning. All tenants are advised to monitor over the coming days and report any recurrence of issues.

Finally, I document the troubleshooting process and repair details for future reference. Thorough documentation provides insights that can speed up solving the next electrical mystery that comes along!


Troubleshooting rare electrical issues requires diligence and know-how to successfully track down the root cause. While challenging, methodically following these steps - gathering tenant clues, understanding the system design, inspecting/testing methodically, isolating the malfunction, and finally pinpointing the exact component failure - has enabled me to solve even the most evasive electrical gremlins in commercial buildings. The reward is keeping tenant business operations running smoothly.