A switchboard can appear normal while a connection behind the cover is operating well above its intended temperature. Common switchboard hot spots are often an early warning that current is not flowing as it should – whether through a loose termination, an overloaded circuit, a deteriorating component or an imbalanced load. Left unaddressed, that heat can damage insulation, shorten equipment life, cause unplanned outages and increase fire risk.
For facilities teams, the issue is not simply finding a warm component. Electrical equipment naturally produces heat under load. The practical task is to identify abnormal temperature differences, understand why they are occurring and arrange corrective work before a defect becomes a safety incident or business interruption.
Why Common Switchboard Hot Spots Matter
Thermal imaging provides a non-invasive way to inspect live electrical assets while they are operating. An appropriately trained technician uses an infrared camera to identify surface temperatures and compare like-for-like components, phases and connections. The resulting thermal image can show where heat is concentrated, giving maintenance teams evidence to prioritise repairs.
A hot spot does not automatically mean a component will fail immediately. Load levels, ambient temperature, enclosure ventilation and the equipment’s design all affect the reading. However, a clear temperature anomaly compared with similar components under similar load is a condition that warrants investigation. It is particularly significant where there is discolouration, a burning smell, damaged insulation, nuisance tripping or a history of circuit faults.
For Australian workplaces, thermal imaging supports a planned electrical maintenance approach. It can complement test and tag programs, RCD testing, visual inspection and asset records, but it does not replace electrical work by a licensed electrician where a defect is identified. The report should clearly record the asset location, image findings, measured temperatures, level of priority and recommended next action.
The Hot Spots Most Often Found in Switchboards
Loose or poorly terminated cable connections
Loose terminals are among the most common causes of localised switchboard heating. A connection with increased resistance generates heat as current passes through it. This can occur at circuit breaker terminals, neutral bars, earth bars, isolators, contactors, busbar joints and main supply connections.
Vibration, thermal expansion and contraction, installation issues, corrosion and repeated load cycling can all contribute to a connection deteriorating over time. A thermal image may show one terminal considerably hotter than the equivalent terminal on another phase. In some cases, heat damage is visible before the enclosure is opened, but relying on visual signs alone means the problem may be found late.
The correct response is not to simply tighten a live connection. A licensed electrician should assess the affected circuit, isolate it where required, inspect for conductor or terminal damage, complete repairs to the manufacturer’s requirements and verify the repair under operating conditions.
Overloaded circuits and protective devices
An overloaded circuit can make cables, breakers, fuses and terminals run hotter than expected. This may happen when a workplace adds equipment without reviewing available capacity. Common examples include extra workstations in an office, new refrigeration in hospitality, additional machinery in a warehouse, or temporary site loads becoming permanent.
A breaker operating at high temperature is not always defective. It may be responding to genuine demand. The key question is whether the circuit load, cable size, protective device rating and installation conditions remain suitable for the intended use. Thermal findings should be considered alongside load measurements and the circuit’s operating history.
Repeated tripping should never be managed by fitting a larger breaker without an electrical design assessment. Doing so can remove protection from conductors that are not rated for the increased current. The safer outcome may be load redistribution, a dedicated circuit, equipment scheduling changes or a switchboard upgrade.
Uneven phase loading
Three-phase switchboards rely on loads being reasonably balanced across phases. When one phase carries significantly more current than the others, associated components may run hot while other phases remain comparatively cool. This is common in buildings where single-phase loads have been added progressively without a review of distribution.
An imbalance can affect supply efficiency and place unnecessary stress on one phase, its protective devices and cable terminations. In severe cases, it may also contribute to neutral conductor heating. Thermal imaging can reveal the temperature pattern, while electrical measurements confirm current levels and help an electrician determine whether loads should be redistributed.
Deteriorating circuit breakers, fuses and contactors
Internal wear, ageing contacts and mechanical failure can increase resistance inside protective devices and switching equipment. A circuit breaker or contactor may appear intact externally but show abnormal heat at its body or terminals when compared with neighbouring devices carrying similar loads.
This category needs careful interpretation. Different brands, ratings and load profiles will operate at different temperatures. A qualified assessment compares equivalent equipment and considers manufacturer guidance, current draw and the condition of the surrounding enclosure. Where a device is degraded, replacement is generally preferable to waiting for a failure that could stop production, refrigeration, IT systems or essential services.
Corrosion, moisture and contamination
Switchboards installed in plant rooms, workshops, food preparation areas, coastal locations or dusty industrial environments can be affected by moisture, salt, oil, insects and airborne contaminants. Corrosion at a connection increases resistance and can create a hot spot. Dust build-up can also reduce ventilation and retain heat within an enclosure.
The repair may extend beyond replacing a corroded terminal. The source of moisture ingress, inadequate enclosure sealing, failed gland or poor housekeeping practice also needs attention. Otherwise, the same condition is likely to recur. This is one reason thermal inspection findings should be integrated into a broader preventive maintenance plan rather than treated as isolated defects.
Busbar and main connection issues
Main switch connections and busbar joints carry substantial current, so a developing fault in these areas can have serious consequences. Thermal anomalies at incoming supply terminations, busbar links or main isolators should be assessed promptly, particularly where the temperature is rising during normal peak demand.
Access restrictions and live electrical risks make this work unsuitable for unqualified personnel. Switchboard covers should only be removed, and corrective work completed, by authorised and competent electrical workers using the required safety controls. A business should maintain clear access to switchboards and avoid storing stock, cleaning materials or other items in front of them.
What Makes a Thermal Inspection Useful
A thermal scan is most informative when equipment is under representative load. Scanning an almost idle switchboard may not reveal a fault that appears during peak production, afternoon cooling demand or a busy service period. For sites with variable operations, it may be appropriate to schedule imaging during typical high-load conditions.
Good reporting matters as much as the images themselves. Each identified issue should be traceable to a specific board, circuit or component, with visible and thermal images where appropriate. The report should distinguish between urgent defects, planned maintenance items and observations to monitor at the next inspection. This gives facilities managers a defensible record for maintenance planning, budget discussions and audit preparation.
At AGE Electrical Testing Services, thermal imaging inspections can be coordinated with other workplace electrical safety services to reduce disruption and keep compliance records organised. For multi-site businesses, consistent asset naming and digital reporting make it easier to see recurring issues and confirm that corrective actions have been closed out.
How to Control Common Switchboard Hot Spots
The most effective control is a documented process: inspect, assess, repair, verify and retain the record. Thermal imaging identifies symptoms, while licensed electrical work resolves the underlying cause. Once repairs are complete, a follow-up scan under load can confirm that temperatures have returned to an acceptable pattern.
Facilities managers can also reduce risk by maintaining unobstructed switchboard access, reporting flickering lights or repeated breaker trips early, documenting changes in electrical loads and ensuring temporary equipment is not treated as a permanent installation. Where sites expand or add high-demand plant, arrange a capacity review before the new load is connected.
Inspection frequency depends on the site, equipment criticality, environment, load profile and maintenance history. A manufacturing facility with continuous high-current equipment may require a different approach from a low-load office tenancy. The right interval is one that reflects actual risk, not a generic calendar reminder.
A thermal image is valuable because it turns hidden heat into actionable evidence. When a report identifies an abnormal switchboard temperature, timely investigation protects people, equipment and operations – and gives your business a clear record that electrical risks are being actively managed.
To have workplace switchboards scanned for developing hot spots, AGE Electrical Testing provides commercial electrical thermal imaging across Australia. Enquire about thermal imaging.
