Infrared inspection for electrical, mechanical and building systems

An infrared camera measures emitted energy in the long wave or mid wave infrared band and converts it to apparent temperature. The number on the screen depends on emissivity, reflected heat from nearby sources, distance, atmosphere and viewing angle, which is why training matters as much as the camera. Passive thermography looks at equipment under its normal load. Active thermography adds a controlled heat pulse to a part and watches how the heat flows, revealing subsurface defects in composites and bonded structures. Both are covered by consensus guidance such as ASTM E1934, the standard guide for examining electrical and mechanical equipment with infrared thermography.

Electrical surveys are the most common job. A thermographer scans switchgear, panelboards, motor control centers, transformers, bus duct, disconnects and connections under load and ranks anomalies by temperature rise over a similar component or ambient. NFPA 70B, the standard for electrical equipment maintenance, includes infrared thermography in its maintenance program guidance, and many insurers ask facilities for a periodic infrared survey. Panels often need to be opened by qualified electrical workers wearing appropriate PPE under NFPA 70E, or fitted with infrared windows, because glass and closed covers block the infrared band.

Mechanical, building and process applications

• Mechanical: bearings, couplings, belts, gearboxes, motors, steam traps and misalignment heat.
• Building envelope: missing or wet insulation, air leakage and thermal bridging, best done with a sufficient indoor to outdoor temperature difference.
• Roofs: trapped moisture under low slope roofs, usually surveyed after a sunny day as the roof cools in the evening.
• Process and refractory: kiln shells, furnace linings, boiler casings, tank levels and blocked lines.
• Solar arrays and electrical distribution, often combined with wind turbine drone inspection style aerial work for large sites.

Active infrared thermography inspection for composites

Flash, lock in and pulsed thermography heat a part briefly and record the surface cooling. Delaminations, disbonds, impact damage, water ingress in honeycomb and porosity near the surface slow or redirect the heat and show up as contrast. It is fast over large areas of carbon fiber and glass fiber laminates, and is often paired with ultrasonic testing for sizing.

1. You share the equipment list or building scope, load conditions and access rules.
2. The provider plans the route, the panels that must be opened and the electrical worker who will open them.
3. The survey runs with equipment at normal load, ideally at least 40 percent of rated load for electrical gear.
4. Each anomaly is photographed in infrared and visible light with location, load and temperature rise.
5. A report ranks findings by severity with recommended actions and timing.
6. A follow up scan after repairs confirms the fix.

A one day electrical survey of a mid sized plant is common, and reports typically arrive within 2 to 5 business days.

Most surveys are priced by the day or half day, sometimes per panel. The number of panels, whether covers can be opened safely, night work for building and roof surveys, drone use and report detail drive the total. Active thermography of composites is usually lab work priced per part or per hour.

Travel and the cost of a qualified electrician to open panels are often separate.

Ask for a Level I thermographer at minimum to collect images and a Level II to analyze and report, certified under an employer program based on ASNT SNT-TC-1A or CP-189, or under a central scheme. For electrical work, ask whether the thermographer is qualified to work near energized equipment or will be accompanied by a qualified electrical worker. Reference documents worth naming in your request include ASTM E1934 for electrical and mechanical surveys and NFPA 70B for maintenance program context. For aerospace composites, NAS 410 personnel and NADCAP scope for the method may apply.