Common Electrical Faults in Commercial Properties and What to do About Them

Electrical systems are the backbone of any commercial property—whether it’s an office, retail space, industrial unit, or public building. However, faults in these systems can lead to costly downtime, serious safety risks, and even legal consequences if left unchecked.

In this guide, we’ll walk you through the most common electrical faults in commercial wiring, signs to watch for, and best practices for troubleshooting commercial electrical faults effectively and safely.

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Why Electrical Faults Are a Serious Issue in Commercial Buildings

From lost productivity to fire hazards, common electrical issues in commercial buildings can have a major impact on your operations. Ignoring small warning signs may result in:

🔌 Equipment damage

🔥 Fire risk

⚠️ Health and safety violations

💼 Business interruptions

❌ Insurance voids

That’s why early detection and regular maintenance are key to staying compliant and protected.

Most Common Electrical Faults in Commercial Properties

🔌 1. Overloaded Circuits

One of the most frequent problems in commercial buildings. Too many devices drawing power from the same circuit causes overheating and tripping.

Signs:

• Frequent tripping of circuit breakers, but not immediately and consistently

• Warm or buzzing sockets

• Dimming lights when equipment is used

Fix:

1. Assess the current load on each circuit to identify any signs of overloading or imbalance.

2. Rebalance loads by shifting equipment between circuits where possible.

3. Add new circuits if existing ones can’t safely support the equipment.

The electrician who originally installed the circuits should have balanced the loads across them to reduce the risk of overload. If that wasn't done properly, it's important to have a qualified electrical contractor review and correct the setup to prevent future issues.

⚡ 2. Faulty or Outdated Commercial Wiring

Ageing infrastructure or improper installations can lead to arcing faults, short circuits, or total power failure. Especially if it’s left unchecked for long periods of time.

Signs:

• Flickering lights

• Discoloured sockets or switches

• Burning smells

Fix:
Have a qualified electrician inspect, test and replace degraded or unsafe wiring to meet current UK standards (BS 7671)

🔦 3. Lighting Control (LC) Faults

Faulty switches, damaged wiring, or failures in DALI or PLC systems can affect workplace lighting—impacting energy efficiency and safety.

Signs:

• Lights won’t switch on or off

• Certain zones have no power

• Malfunctioning motion sensors or dimmers

Fix:

1. Check the circuit breakers to ensure both the lighting control circuit and the lighting circuits are switched on.

2. Visually inspect the lighting control (LC) box or hub for error messages or fault indicators. These are typically located in riser cupboards next to the distribution boards.

3. Reprogram the control system if needed, or contact your lighting control engineer for support.

4. If no recent changes have been made, the issue may lie with the control unit itself — in this case, it's best to call the lighting controls engineer.

While cheap lighting control systems might seem cost-effective during installation, investing in a reliable, proven solution helps reduce downtime and avoid unnecessary callouts in the long run.

🧯 4. Loose Electrical Connections

Loose terminals in sockets, distribution boards, or light fittings can generate heat and eventually fail.

Signs:

• Intermittent power loss

• Buzzing sounds from sockets or boards

• Heat marks or scorched components

Fix:
This isn’t something a business owner or facilities team should handle themselves. Instead, call a qualified electrician to carry out a professional inspection. Your electrical contractor will check for loose connections, tighten terminals, replace any damaged outlets, and use thermal imaging to detect potential issues as part of routine maintenance.

🔌 5. RCD and Circuit Breaker Failures

Residual Current Devices (RCDs) and breakers protect against shock and fire. If they fail or trip without obvious cause, the breaker may need replacing.

Signs:

• Breakers trip frequently, even with no load on the circuit (nothing plugged in)

• RCDs don’t reset or test properly (even after pressing the ‘Test’ button on the device)

• Circuits remain dead despite reset attempts

Fix:

1. Unplug all connected devices.

2. Functionally test all breakers and RCDs to see if power turns on/off without tripping, if so, replug equipment back in until it trips again and try to replicate the issue. Once it’s clear that the same device is causing it to trip, you have your fault.

3. Press the ‘T’ or ‘Test’ button on each RCD — they should trip. If they don’t, the RCD is faulty and must be replaced by a qualified electrician.

4. Check for overloading and confirm that circuits are balanced appropriately, as mentioned earlier.

5. If the issue persists, contact a reputable commercial electrical contractor to diagnose and resolve the problem.

Troubleshooting Commercial Electrical Faults Safely

Never attempt to fix commercial electrical faults without proper training. Here’s what to do instead:

1. Isolate the issue – If safe, switch off the affected circuit or area, as it could be a loose connection and require immediate action to reduce fire risk.

2. Report faults immediately – Log and escalate the problem to a qualified electrician.

3. Book a professional inspection – Arrange an assessment from a commercial electrical contractor.

4. Keep records – Note immediate symptoms, date/time, and outcomes for safety and insurance purposes. It also helps speed things up if the issue arises again.

Prevention Through Planned Preventative Maintenance

Many of these faults are avoidable with regular checks. A professional maintenance plan may include:

• Annual Electrical Installation Condition Reports (EICRs)

• Routine testing of RCDs and circuit breakers

• Periodic inspection of lighting control systems

• PAT testing for all plug-in devices

• Emergency lighting testing monthly and annually

• Visual and thermal checks of distribution boards and cabling

While not guaranteed, Preventative maintenance helps drastically minimise the likelihood of disruptions, lower repair costs, and the likelihood of emergency faults.

Need Help with Commercial Electrical Faults?

At Carter’s Electrical Services, we specialise in diagnosing and resolving electrical faults in commercial wiring—quickly, safely, and in full compliance with UK regulations.

Whether you're experiencing power issues, lighting failures, or need a full inspection, our qualified electricians are here to help. We also offer comprehensive planned preventative maintenance (PPM) packages to keep your systems running smoothly all year round.

📞 Get in touch today to schedule an inspection or discuss your business’s electrical maintenance needs.

Frequently Asked Questions

• What are the most common electrical faults in commercial properties?

  Overloaded circuits, ageing wiring, faulty lighting controls, loose connections, faulty appliances and RCD failures are among the most common electrical issues in commercial buildings.

• How do I spot electrical faults in my building?

  Look out for flickering lights, burning smells, warm outlets, buzzing noises, or frequent breaker trips. If you notice these, contact an electrician immediately.

• Can small electrical faults cause fires?

  Yes. Faulty wiring, overloaded circuits, and loose connections are among the leading causes of electrical fires in UK commercial properties. Statistics show that approximately 19% off all commercial fires are due electrical distribution faults.

• What’s the safest way of troubleshooting commercial electrical faults?

  Isolate the circuit if safe, report the issue, and hire a qualified commercial electrician. Never attempt DIY fixes in a workplace setting. 

• How often should I have my commercial wiring inspected?

  An EICR should be carried out at least every 5 years, or more often in high-risk environments. Regular maintenance in between is also recommended.

• Who is responsible for maintaining commercial electrical systems?

  The business owner, duty holder, facilities manager or building manager is legally responsible for maintaining safe electrical systems under UK regulations.