Thermal Imaging (Infrared) Inspections
Loose or overloaded electrical connections get hot before they fail. An infrared camera shows heat as a picture, so technicians can find problems before they cause fires or outages. But taking the images means working near live equipment, so safety matters.
- Electricians
- Maintenance
- Thermographers
What it finds
- Loose, corroded or poorly made connections
- Overloaded circuits and unbalanced loads
- Failing breakers, fuses and contactors
- Overheating motors, bearings and transformers
- Mechanical problems such as worn belts and couplings
- Building problems like insulation gaps and moisture
Safety first
- Electrical thermography usually requires the equipment to be energized and under load, with covers open or removed. That exposes the worker to shock and arc flash hazards. See Arc Flash.
- Follow the employer's electrical safety program and NFPA 70E. Use the arc flash labels to find the boundary and required PPE. See NFPA 70E.
- Only qualified persons should open panels. Use arc-rated clothing, face shields, insulating gloves and hearing protection as required. See Arc-Rated Clothing.
- Use infrared windows (viewing ports) in panels where possible, so you can scan without opening them.
- Have a second person present, and a plan for emergencies.
- Stay out of the limited approach boundary unless qualified and authorized. See Energized Work Permits.
Getting good results
- Scan when equipment carries at least about 40 percent of its normal load, and ideally more
- Set emissivity and reflected temperature correctly; shiny metal can look cooler than it is
- Compare similar parts (phase to phase) and note ambient temperature
- Take both infrared and visual photos and record the load and location
- Report temperature differences and a priority (for example, monitor, repair soon, repair now)
- Follow up after repair with a new scan
Limits
Thermal imaging cannot see through enclosures. A connection may look fine at low load and fail at high load. It is one tool in a maintenance program alongside cleaning, torque checks and testing. See Electrical Equipment Maintenance (NFPA 70B).
Standards & references
Last updated: