Today's thermal imagers, which produce live images of the heat emitted from equipment, are rugged, easy to use and much more affordable than just a few years ago. This makes them highly practical and cost-effective solutions for everyday electrical maintenance. To use one, a qualified technician or electrician points the imager at the equipment in question, scans the immediate area for unexpected hot spots, then squeezes the trigger to capture a specific image. When the inspection is complete, the saved images can be uploaded to a computer for closer analysis, reporting and future trending.

Although thermal imagers may be simple to operate, they are most effective in the hands of a qualified technician who understands electrical measurement and the equipment to be inspected. For anyone using this type of imager, the following three points are especially important.

• Point 1: Loading
The electrical equipment being inspected must be under at least 40% of nominal load in order to detect problems with a thermal imager. Maximum load conditions are ideal, if possible.

• Point 2: Safety
Electrical measurement safety standards still apply under NFPA 70E[1]. Standing in front of an open, live electrical panel requires personal protective equipment (PPE). Depending upon the situation and the incident energy level (Bolted Fault Current) of the equipment being scanned, this may include:
- Flame resistant clothing
- Leather-over-rubber gloves
- Leather work boots
- Arc flash rated face shield, hard hat and hearing protection, or a full flash suit

• Point 3: Emissivity
Emissivity describes how well an object emits infrared energy or heat. This affects how well a thermal imager can accurately measure the object's surface temperature. Different materials emit infrared energy in different ways. Every

Objects that have high emissivity emit thermal energy well and usually are not very reflective. Materials that have low emissivity are usually fairly reflective and do not emit thermal energy well. This can cause confusion and incorrect analysis of the situation if the user is not careful. A thermal imager can only accurately calculate the surface temperature of an object if the emissivity of the material is relatively high, and/or...(Read whole article)