How to Troubleshoot uncommon Electrical Control Panel Issues

Electrical control panels are crucial components of industrial equipment and facility operations. As an electrician, I often get called to diagnose and repair issues with control panels when something goes wrong. While some problems like blown fuses or tripped breakers are common and easy to fix, occasionally I run into more obscure and challenging control panel malfunctions that require deeper investigation and troubleshooting. In this guide, I'll share my insights and step-by-step process for identifying and resolving those uncommon electrical control panel problems.

Understanding Electrical Control Panel Components

Before diving into troubleshooting, it's important to have a solid grasp of what's inside a typical industrial control panel and how the components function together. Here's a quick overview:

Having a solid understanding of what's inside the panel and how everything interacts is crucial for troubleshooting effectively.

Initial Troubleshooting Steps

When I get called about an issue with a control panel, the first thing I do is try to gather as much information as I can about what exactly is happening or not happening. Here are some initial troubleshooting steps I take:

Starting with these basic steps helps me narrow down the scope of the problem and determine where to focus my investigation.

Common Electrical Panel Issues

While every malfunction is unique, there are some fairly common electrical control panel problems I encounter repeatedly:

Power Supply Failures

Power issues like a dead power supply are one of the most frequent issues. Warning signs include no lights/displays, intermittent reboots, and controller memory errors. I isolate supply output voltages with a multimeter and check fuses, breakers, cable connections, rectifiers, and capacitors for damage. Replacement of defective components is required.

Controller Malfunctions

Problems with PLCs, PCs, or sequencers usually require troubleshooting I/O communications and addressing, scanning for firmware errors, and testing processor and memory status. Controller replacement may be necessary if hardware has failed.

Blown Fuses

Repeated blown fuses point to overloads and short circuits. I use my multimeter to trace currents through affected lines and loads. Removal of faulty devices and wiring corrections is typically needed.

Contactor/Relay Failures

Failed contacts, coils, and mechanical linkages in contactors/relayers will disable control of connected loads. buzzing sounds, smoking, and warm coils are telltale signs. Replacement of affected contactor/relays resolves the issue.

Loose Field Wiring

Intermittent connections at terminals or in field junction boxes can lead to erratic behavior and digital/analog signal faults. Inspection with wiggling and re-termination of loose wires solves these kinds of problems.

Faulty Bus Network Cables

Damaged or improperly installed fieldbus cables are prone to communication errors and data faults. Testing with a cable certifier, replacing defective cable segments, and correcting poor terminations will fix network wiring issues.

While these kinds of problems make up a majority of the panel issues I see, every once in a while I'll run into something more obscure which requires some real sleuthing to figure out. Let's look at some examples of these more challenging scenarios.

Uncommon Electrical Panel Issues and Troubleshooting Tips

Over the years, I've learned there are some lesser known electrical control panel problems that can occur and manifest in complex ways. Here are a few that have given me a headache:

Intermittent Signals or "Ghost" Logic Changes

The Problem: Control logic seems to sporadically change or activate on its own, equipment cycles without apparent cause, erratic intermittent signals from field devices.

Causes: Radio frequency (RF) noise being coupled onto sensor wiring or power supply lines causing electrical interference and false signals. Also, poor isolation between high voltage (AC) wiring and low voltage (DC) logic/control can introduce transients during power events.

The Fix: Check for failing surge suppressors and install ferrite chokes on I/O and power connections to attenuate RF. Improve separation between high voltage and low voltage wiring. Twist wire pairs. May also need to replace sensors/field devices communicating intermittently.

Overheating Components and Unexplained Shutdowns

The Problem: System runs fine initially but shuts down after running for some period of time. Temperature alarms from drives, PLCs or panel interior overheating without explanation.

Causes: Excessive electrical load and poor ventilation leads to overheating of internal components like PLCs, variable frequency drives or transformers. Dust/debris buildup on heat sinks and ventilation ports blocks airflow.

The Fix: Accurately measure operating power demand and compare to panel ratings to identify underrated supply. Improve cooling airflow paths, add inlet/exhaust fans. Clean heat sink fins and ventilation ports. Replace defective components.

Memory and Data Corruption Issues

The Problem: Program and data files mysteriously change, corrupted or disappear completely. PLC memory fault alarms. Unexplained defaulting of setpoints.

Causes: Electrical transients and power interruptions cause memory and data errors. Failing non-volatile storage media corrupts files. Software bugs and malware may randomly overwrite memory.

The Fix: Install uninterruptable power supply (UPS) backup power. Use memory with built-in error checking like ECC RAM. Update firmware and scan for viruses. Replace defective hardware components.

As you can see, uncommon control panel issues tend to stem from environmental and physical factors like heat, vibration, noise and deteriorating components. Tests, measurements and thorough inspection are crucial to identifying and correcting the root causes.

When to Call for Professional Help

Some control panel problems can be complex and dangerous to troubleshoot, especially issues involving hazardous voltage areas. Here are some warning signs that it's time to call a professional electrician or system integrator for assistance:

While I'd always encourage trying basic troubleshooting steps first, knowing when to call for expert help can save you from costly damage and hazardous situations. For uncommon or difficult electrical control panel issues, the professionals have the tools, training and experience to diagnose and correct the problem safely and efficiently.


Troubleshooting electrical control panels takes thorough knowledge of the system components and methodical isolation of potential issues. While simple problems often involve blown fuses or loose wiring, complex malfunctions require a deeper investigation into hardware, software and physical environment factors. Being aware of common failure modes along with some less common pitfalls will help you pinpoint and correct the inevitable issues that come up over time. With diligence and the right troubleshooting approach, even obscure control panel problems can be solved effectively. Let me know if you encounter any particularly perplexing issues - I'm always happy to help a fellow electrician track down those tricky gremlins in our critical equipment and get things running smoothly again!