Thermographic Surveys

Thermographic Surveys

Thermographic surveys are used to determine the temperature of electrical components

If any unusually high temperatures are detected using a thermal imaging camera, it would indicate an imminent risk to any electrical distribution system.

Why undertake a thermographic survey?

The objective of a thermographic survey is to identify abnormally high temperatures within electrical distribution systems. Any high temperatures within electrical components are often indicative of imminent or possible problems. Early identification of these faults is essential in order that corrective action can be undertaken before the problem escalates. Electrical circuits and components often fail because of fatigue, defective components, contamination, or just loose connections due  to poor workmanship, but all failing components have one thing in common, they will always have a rise in temperature or ‘hot spot’ prior to failure.

The Institution of Engineering and Technology (IET) recognises the benefits of performing thermographic surveys of an electrical distribution system, as a supplement to a periodic inspection and test. It is not, however, a substitute for a periodic Inspection and Testing programme or documented routine maintenance programme.

Is there any additional guidance available?

Guidance on the scope of thermographic survey is given in IET Wiring Regulations Eighteenth Edition BS 7671:2018 Guidance Note 3, Inspection and Testing (Chapter 4.9)

What is the optimum time to take a thermographic survey?

It is imperative that as many circuits as possible are in operation whilst carrying out the thermographic survey as it is only when the electrical system is under load, that weaknesses (hot spots) are most readily identified.

Building fabric is a factor in effective thermal imaging. In order to gain the maximum benefit from the survey, it is better to remove covers or open doors wherever possible, as thermal imaging cameras measures surface temperature. Excessive temperatures can however still be identified where this is not practical, as heat will radiate out and warm the covers and doors.

What items of electrical equipment are typically included in the thermographic survey?

In the first instance, electrical equipment which cannot be isolated or equipment which is giving cause for concern. A methodical approach, from source of supply through to final circuits is the normal procedure, but not always possible. Preparation for a thermographic survey is the key in order to maximise the engineer’s time and efficiency whilst on site.

The following list is not exhaustive:

  • Main LV transformer
  • Main switch panel
  • Main distribution boards
  • Sub distribution boards
  • Consumer units
  • Supplies to fixed equipment
  • Cables emanating from substations, MCCs, control panels and distribution boards
  • Motor or motor controlling equipment/wiring systems integral to plant and machinery enclosures

What is the outcome of a thermographic survey?

Suspected problems identified during the course of a survey are photographed, with both thermal and digital images presented in a report. Guardian would give an explanation as to the cause of problems identified, wherever possible. In the report there will also be a listing of all equipment surveyed for reference purposes, which will satisfy Electricity at Work Regulations 1989, and IET Wiring Regulations Eighteenth Edition BS 7671:2018 Guidance Note 3, Inspection and Testing (Chapter 4.9)

Guardian would undertake the survey systematically, looking at distribution equipment within the premises, as well as switchgear, and where applicable infrastructure. The work is most cost effectively completed with the assistance of the client. Guardian would require a member of staff to accompany an engineer whilst on site, thereby providing access to areas when required, as well as providing the most direct route around the premises.

The thermographic report is produced in Microsoft Word format and can be supplied on the interactive website, TraQ-it, as a bound hard copy or on CD/USB

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