How a Thermal Imaging Survey Prevented an Unplanned Shutdown at a Multi-Tenanted Office Building

TL;DR - Key Takeaways

• A scheduled thermal imaging survey at a multi-tenanted office complex detected a critically overheating busbar, with a temperature differential of over 40 degrees Celsius above ambient.

• The fault had no visible symptoms before the survey - no burning smells, no tripped breakers.

• Because the fault was found proactively, remediation was planned during an agreed shutdown window, with zero unplanned disruption to tenants.

• An unplanned electrical shutdown in a multi-tenanted commercial building can cost tens of thousands of pounds in contractor call-outs, lost productivity, and tenant compensation.

• Thermal imaging surveys detect faults that standard fixed wire testing cannot, making them a critical complement to any EICR cycle.

Introduction

Most electrical faults in commercial buildings do not announce themselves. There is no burning smell, no tripped breaker, no visible sign of deterioration. They develop silently inside distribution boards, busbars, and switchgear until they can no longer be contained.

That is exactly what a Protest ES Ltd engineer encountered during a scheduled thermal imaging survey at a multi-tenanted office building in the South East. What began as a routine inspection ended with the prevention of a potentially serious unplanned shutdown, and a clear demonstration of why proactive electrical testing pays for itself many times over.

This article walks through what was found, what was done, and what it would have cost to do nothing.

The Building and the Survey Brief

The building in question was a five-storey, multi-tenanted commercial office complex with a mix of private offices, open-plan floors, and shared common areas. It housed several independent businesses, meaning any electrical failure affecting the main distribution system would have an immediate, measurable impact on multiple tenants simultaneously.

The facilities manager commissioned Protest ES Ltd to carry out a thermal imaging survey as part of a planned annual compliance cycle. The survey was not reactive - there had been no faults, no complaints, and no indication of any electrical problem. It was simply good practice.

For duty holders responsible for multi-tenanted buildings, thermal imaging surveys are increasingly recognised as a critical layer of preventive maintenance, sitting alongside fixed wire testing in a well-structured electrical compliance programme.

What the Thermal Imaging Survey Found

Within the first hour of the survey, the Protest ES Ltd engineer identified two thermal anomalies in the ground floor distribution room. Both were invisible to the naked eye. Under the thermal camera, they showed a clear and concerning heat signature.

Hotspot 1: A Critically Overheating Busbar

The most serious finding was a busbar running between the main LV distribution board and a secondary consumer unit. The busbar section showed a temperature differential of over 40 degrees Celsius above the ambient reading at an adjacent connection point - a clear indicator of a high-resistance fault, most likely caused by a loose or corroded connection that had developed over time.

At that temperature differential, the fault would typically be classified as a Priority 1 defect, representing an immediate risk of component failure or fire. Had it been left undetected, the busbar could have failed without warning during peak load, triggering a total loss of supply to multiple floors and requiring emergency out-of-hours intervention.

Hotspot 2: Unbalanced Load on a Secondary Distribution Board

A secondary finding showed an unbalanced phase load on one of the floor-level distribution boards. While less immediately critical than the busbar fault, the imbalance was causing measurable overheating on two MCBs. Left uncorrected, this type of fault accelerates component wear and increases the risk of nuisance tripping, or a sustained fault that damages downstream equipment.

What Happened Next: Planned Remediation Over Emergency Call-Out

Because both faults were identified proactively, during a scheduled survey rather than following a failure, the facilities manager had full control over the remediation timeline.

A planned maintenance window was agreed with the building's tenants. The Protest ES Ltd electrical remedials team attended during the pre-arranged shutdown period to address both issues. The busbar connection was cleaned, re-torqued, and tested. The phase imbalance was corrected by redistributing the load across the affected distribution board.

Total unplanned disruption to tenants: zero.

This is the defining advantage of proactive thermal imaging surveys. Rather than attending as an emergency response to a failure, Protest ES Ltd was able to schedule electrical remedial works around the building's operational calendar. The work was completed cleanly, documented formally, and signed off as part of the building's compliance record.

The Real Cost of an Unplanned Electrical Shutdown

To understand the value of what was prevented, it is worth considering what an unplanned shutdown at this type of building typically costs.

Out-of-hours emergency call-out for a commercial electrical contractor in the UK currently runs at between £500 and £1,500 for the first two hours, depending on scope. But that is just the contractor cost. In a multi-tenanted office building, an unplanned shutdown during business hours also means:

• Lost productivity across every affected tenant

• Potential data loss or equipment damage for businesses reliant on continuous power

• Liability exposure if the building manager is found to have had prior knowledge of a fault

• Potential insurance complications if the root cause is traced to a failure of due diligence

• Reputational damage with existing and prospective tenants

For a five-floor building with multiple occupiers, the total cost of a single unplanned shutdown can easily reach five figures. The thermal imaging survey that prevented it cost a fraction of that.

Why Thermal Imaging Is Different From Other Electrical Tests

A fixed wire test (EICR) verifies insulation resistance, continuity, and protection under specific test conditions. What it cannot reliably detect is a developing thermal anomaly inside a live, closed distribution board under operational load. For a detailed explanation of how thermal imaging detects hidden electrical faults, our earlier guide covers the process in full.

The two tests complement each other; neither replaces the other. A growing number of facilities managers and duty holders now include thermal imaging as a standalone item in their annual maintenance cycle, not simply as an add-on to other tests.

Is Your Building Due a Thermal Imaging Survey?

If your building is multi-tenanted, operates critical infrastructure, or has distribution equipment that is more than five years old, a thermal imaging survey is a proportionate and cost-effective precaution. Protest ES Ltd carries out thermal imaging surveys across commercial, education, healthcare, and public-sector buildings throughout the UK. Get a quote for your building or speak to our team about incorporating thermal imaging into your annual compliance programme.

Frequently Asked Questions

What is a thermal imaging survey for electrical installations?

A thermal imaging survey uses an infrared camera to measure heat signatures across electrical components, switchgear, distribution boards, and busbars while they are live and under load. It identifies hotspots that indicate high-resistance faults, overloading, or deteriorating connections, often long before those faults cause a failure.

How is thermal imaging different from an EICR?

An EICR (fixed wire test) checks the electrical installation's continuity, insulation, and protection under controlled test conditions. Thermal imaging surveys assess the live installation under operational load and detect thermal anomalies that standard testing cannot reliably identify. The two tests are complementary, not interchangeable.

How often should a thermal imaging survey be carried out on a commercial building?

Most commercial buildings benefit from an annual thermal imaging survey. Buildings with older distribution equipment, high electrical loads, or critical tenants may warrant more frequent inspection. Your electrical compliance consultant can advise on the appropriate frequency based on the building's age, usage, and risk profile.

What happens if a thermal imaging survey finds a fault?

Faults identified are classified by severity, typically Priority 1 (immediate risk), Priority 2 (short-term risk), or Priority 3 (monitoring required). Protest ES Ltd provides a detailed written report for each finding, and our remedials team can attend to carry out the required electrical remedial works, typically within an agreed planned maintenance window.

Is thermal imaging testing disruptive to building occupiers?

No. Thermal imaging surveys are non-invasive and are carried out while the installation is live. There is no requirement to isolate circuits or interrupt supply during the survey itself. Any disruption is limited to the planned remediation work that follows, which can be scheduled to minimise impact on tenants.

What types of faults does thermal imaging typically find?

Common findings include loose or corroded connections causing high-resistance faults, overloaded circuits or unbalanced phase loads, failing contactors or relays, deteriorating cable terminations, and overheating motor control components. All of these are invisible under normal inspection and cannot be reliably detected through standard fixed wire testing alone.

Does my building need a thermal imaging survey if it has recently had an EICR?

Yes. A recent EICR does not replace a thermal imaging survey. The two tests examine different aspects of your electrical installation and together form a more complete picture of its condition. Many building owners and facilities managers commission both as part of an annual compliance cycle to ensure no category of risk is left uncovered.