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.

• Ask tenants to describe the problem in detail. What exactly occurs? Does the power go out completely or just dim? Is it limited to certain circuits or parts of the building? Does it happen at particular times or when certain appliances are in use? The more specific their description, the better.

• Find out how long the issue has been happening. Intermittent problems that come and go randomly are harder to identify than an outage that has persisted for days.

• Ask if they've noticed any pattern to the occurrence. Have they identified anything that triggers the problem or makes it worse/better? This type of information is invaluable.

• Request access to tenant spaces to inspect all electrical equipment during troubleshooting. Offer to schedule visits at their convenience. Their cooperation is essential.

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:

• Main service and metering - Where does the main feed enter the building? How is power metered and distributed?

• Load centers and panelboards - What capacities and voltages are available? Note all panel locations.

• Major equipment - Where are large motors, HVAC units, elevators, etc. fed from? These can cause issues.

• Lighting circuits - How are lighting loads divided? Locate the lighting panels.

• Critical circuits - Note where emergency/backup power originates and what it feeds.

• Power quality devices - Uninterruptible power supplies, power conditioners, and surge suppressors can mask underlying issues.

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:

• At the service entrance - Check for adequate, stable voltage here first.

• At main distribution panels - Voltage should be within 5% of nominal. Deviations point to a broader issue.

• At subpanels on each floor - Helps identify a problem isolated to a certain area.

• At receptacles and lighting circuits - Sample spot measurements to gauge overall drop.

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

• Wire connections - Loose or corroded wires can cause intermittent faults. I tighten and clean connections.

• Breakers and fuses - Check for properly sized fuses/breakers. Signs of overheating can indicate an overload.

• Insulators and bus bars - Look for damaged, overheated, or tracking insulators. Pitted/discolored bus bars also point to issues.

• Grounding and bonding - Verify all ground connections are securely bonded. This is critical for safety.

Conductors and Cabling

• Exposed wiring - Inspect cabling for insulation damage, cracks, burns. Rodents/vermin can chew through insulation.

• Junction boxes - Discoloration, overheating evidence points to loose wiring or overloaded circuits.

Light Fixtures and Receptacles

• Switches and outlets - Check for arcing, pitted contacts, melting - signs of loose connections.

• Lamps and ballasts - Cycling lamps/ballasts can reveal faulty ones intermittently failing.

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:

• Clamp meter - Measures current draw on cables andDetects overloaded circuits.

• Outlet tester - Checks for wiring faults, open grounds, polarity and GFCI function.

• Multimeter - Voltage, resistance and continuity tests pinpoint faults. The Fluke 87V is my go-to multimeter for commercial electrical.

• Thermal camera - Scans breaker panels and wiring for hot spots indicating high resistance connections. This tool has often led me right to the source of elusive electrical gremlins.

• Power quality analyzer - Catches voltage fluctuations, harmonics, transients that point to issues.

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.

• Check connections with voltmeter on ohms setting - any abnormal resistance means a faulty junction.

• Use voltage drop math to calculate bad connections or undersized wiring.

• Wiggle test cables and connections while monitoring voltage - an intermittent will show fluctuations.

• Remove loads one by one to isolate the failing device.

• Check fuses, switches, terminals with a multimeter. Failed components will show abnormal results.

• Carefully disassemble devices and inspect internally for damage. Often it's worn brush contacts or failing windings in motors.

• For control circuits, use a voltmeter to verify operation of sensors and actuators during the malfunction.

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:

• Replace failed breakers, fuses, switches, outlets, wiring.

• Tighten, clean, and secure loose connections.

• Rewire undersized or damaged cables.

• Repair or replace malfunctioning equipment.

• Correct code violations that could cause hazards.

• Implement power quality solutions if voltage fluctuations or noise is the cause.

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!

Conclusion

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.