An electrical thermographic survey uses an infrared camera to find heat caused by loose connections, overloading and failing components while equipment is running under normal load. No shutdown is needed. It picks up developing faults that an EICR, which relies largely on dead testing and visual inspection, can miss between periodic inspections, and it gives you a chance to fix them before they cause downtime or a fire.
How does a thermographic survey work?
A thermographic survey is a non-invasive inspection of live electrical equipment. A trained thermographer scans panels, connections and components with a thermal imaging camera while they are carrying their normal working load.
The principle is simple. Loose or high-resistance connections, overloaded circuits and phase imbalance all generate heat. That heat shows up on camera as a hotspot, often well before the fault causes visible damage or failure. Each finding is recorded with a thermal image, a matching digital photo and temperature data, so the report shows exactly what was flagged and why.
Thermal imaging complements an EICR; it does not replace one. An EICR checks the condition and safety of the installation against BS 7671. A thermographic survey shows how the installation behaves under real operating conditions, which reveals a different set of problems.
What equipment does a survey cover?
A survey covers the equipment that carries and controls power through a building. That typically includes LV switchgear, main and sub-distribution boards, motor control centres, control panels, switch fuses and isolators, busbar systems and tap-off units, transformers and UPS systems.
The asset list should be agreed before the visit. A warehouse with heavy motor loads has different critical points from an office with server rooms and UPS systems. Agreeing the scope in advance means nothing critical is missed and the time on site is used efficiently. Because the survey is carried out with equipment live, covers usually need to be removed safely by a competent electrician, so access and safe systems of work need planning too.
What faults can thermal imaging find?
Thermal imaging finds faults that produce heat under load, many of which are invisible to normal inspection. The most common findings are:
- loose or high-resistance connections at terminals, busbars and cable lugs
- overloaded circuits and conductors
- phase imbalance on three-phase supplies
- failing circuit breakers, fuses and contactors
- deteriorating switchgear and isolators
An EICR is largely carried out with circuits isolated, so it cannot always show how a connection behaves when current is flowing. A connection can pass a dead test and still overheat under load. That is why thermal surveys are often scheduled between periodic inspections, to catch developing faults early.
Is a thermographic survey a legal requirement?
No UK regulation requires thermographic surveys by name. They are a recognised way of managing electrical risk rather than a statutory test in their own right.
They do, however, support your duties under the Electricity at Work Regulations 1989, which require electrical systems to be maintained so as to prevent danger. A survey report is good evidence that the installation is being monitored under real operating conditions, and it strengthens your maintenance records.
Insurers are another driver. Some insurers expect regular thermographic surveys as part of a risk management programme, particularly for larger, older or higher-risk installations. If you are unsure, check your policy conditions or ask your broker.
How often should you have one?
Frequency should be risk-based. The criticality of the equipment, its load profile, its age and any insurance conditions all influence the interval. Annual surveys of critical distribution equipment are common, and higher-risk sites with heavy or fluctuating loads may need them more often.
The simplest approach is to build the survey into your planned preventative maintenance calendar, so the interval is tracked rather than remembered. Hotspots also often mean wasted energy, so fixing them can reduce running costs as well as risk.
What should the report include?
A good report should include:
- a thermal image and a matching digital photo of each flagged component
- the measured temperatures and load conditions at the time of the survey
- a severity rating for each finding, so remedial work can be prioritised
- the likely cause and a recommended action
- reference to recognised practice, such as ISO 18434-1 for condition monitoring using thermography
Agree the report format and delivery timescale before the survey. The most useful reports link findings directly to remedial actions, so problems are fixed rather than filed.
How do you choose a survey provider?
Ask about the thermographer’s training. A recognised thermography qualification, such as PCN or ITC Level 2 or above, combined with electrical inspection and testing experience, means images are interpreted correctly and false alarms are avoided.
Confirm that the survey will be carried out under normal load, that risk assessments and method statements will be provided in advance, and how removing covers from live equipment will be managed safely. Finally, check who will carry out any remedial work and how quickly.
Key takeaways
- Thermographic surveys are carried out under normal load, so no shutdown is required.
- They find loose connections, overloading, phase imbalance and failing components that an EICR can miss.
- No UK regulation requires them by name, but they support duties under the Electricity at Work Regulations 1989 and may be an insurance condition.
- Survey frequency should be risk-based and is often built into the PPM calendar.
- Look for qualified thermographers and reports that rank findings by severity and link them to remedial actions.
Delta First can arrange thermographic surveys alongside its commercial electrical maintenance and EICR work, with remedial works quoted and carried out by our own electrical team. The survey record sits alongside your EICRs, emergency lighting tests and other certificates as part of our full compliance management.
Talk to Delta First
Delta First Building Services is a Colchester-based M&E contractor working across Essex, Suffolk and London, with commercial work in Norfolk. Our directly employed electrical team is supported by vetted specialist subcontractors where extra certification is needed, and we offer genuine 24/7 emergency cover. Get in touch to arrange a survey or quote.