Use thermography to diagnose electrical problems

Trained and certified personnel increases program credibility and reduces liability.

By Brad Gilbertson, Sandhills Thermal Imaging

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In brief:

  • Without an electrical preventive maintenance program, management takes on a greater risk of serious electrical failure, and the resulting consequences.
  • Adding thermographic surveys to a maintenance program can bring significant cost savings to the plant’s operation. But there is more to it than simply purchasing an imager.
  • With a properly implemented program, the documentation serves a higher purpose and helps to justify the funding of the program.

I was recently called to a medium-sized manufacturing plant to discuss providing infrared services during the construction of a new addition. While there, I asked the plant manager and his facility engineer about the predictive maintenance program for their switchgear and the possibility of providing thermographic services. The engineer stated they already had a program in place. The plant had purchased a small IR imager and used it to find “hot spots.” Thermography of electrical switchgear involves imaging the electrical components while they are in an energized or “live” state. They employed a two-person team to walk around the plant looking at switchgear. While both were trained electricians, neither was a certified thermographer. Whenever they found a “hot spot” they fixed it immediately by tightening any loose connections. He stated they could also immediately verify their repairs by using the imager and watching the temperature of the connection drop to a “normal” operating range. The engineer was quite happy with this system, stating it was efficient and no time was wasted by needless reports or sending another worker to fix the problem at a later date. The problem was found and solved on the spot.

What could be the problem with that? The most serious problem is that such a method is in violation of OSHA standards and NFPA 70E: Electrical Safety in the Workplace and NFPA 70B: Recommended Practice for Electrical Equipment Maintenance. If anything, such as an arc flash, were to happen during the survey, the plant would be immediately subject to substantial fines, not to mention damage to equipment, loss of production, and the serious injuries or loss of life of plant workers. This plant’s procedures were cobbled together in the belief that these time-saving shortcuts will also save money. The costs associated with a single accident would likely wipe out all the savings associated with previous shortcuts.

There were no pre-planned routes for them to follow; no images of anomalies found that were saved for future reference; no reports generated, documenting the anomalies found during the survey, and no method of tracking problem areas or their repairs and the costs associated with same. And, of course, because they were making repairs “on the fly,” there were no energized work permits. At least there was one positive note: the employees on the IR team performed their tasks in the appropriate PPE.

Safety first

Safety is always our the priority. While we all hear a constant stream of criticism against bureaucracy in general, and OSHA in particular, we need to remember one thing: every standard, law, regulation, or guideline is put into place because someone has been injured or killed by an event the rule is designed to prevent. When dealing with electrical hazards and worker safety, OSHA references NFPA 70E and 70B. Informative Annex J of NFPA 70E describes the process of determining if an energized work permit is required. No energized work permit is required for systems of less than 50 V. The next step is determining if there will be live components exposed. The answer is “yes” because a thermographic survey requires that components be energized and exposed for viewing. And next is the crucial part. What type of work will be performed? Any planned physical contact such as making or tightening connections or removing or replacing components while the system is energized requires an energized work permit. A thermographic survey does not require any physical contact with the exposed energized parts and therefore does not require an energized work permit. Any problems found during the thermographic survey will need an energized work permit if the repairs are to be made while the system is live.

While an energized work permit is not needed for a thermographic survey, repairs are not performed while the thermographic survey is taking place. An energized work permit is issued for each individual item that needs repairs or other work. In other words, it is not a "blanket" permit — for example, “All distribution panels in Maintenance Corridor A” is not a proper listing. The request gives a description and location of the circuit or equipment, along with what work is being done and a justification as to why the work is being conducted while the system is energized. The individuals doing the actual work must describe the procedures they will use and the safe work practices to be employed. Filling out the permit leads the personnel through shock-hazard and arc-flash analysis. It forces them to determine the various safety boundaries and plan methods of restricting the access of unqualified personnel from the work area.

There must be documented evidence of a job briefing, which includes a discussion of any job-related hazards and how they will be mitigated. The approval for the work permit comes from the plant’s general manager and is also signed by the safety manager, as well as the maintenance manager and the person doing the work. While this may seem tedious to some, it helps to ensure not only worker safety, but management awareness and support of the work being performed. This factor can also address a morale issue. In most cases, the maintenance department and its workers are invisible to plant operations until something important breaks. If nothing seems to break, the tendency is not to credit proper and continuous maintenance but rather to believe “that’s how things are supposed to be.” The requests for work permits allow management to see that well-planned and safely executed ongoing maintenance is responsible for the efficient operations of the plant. In this case, visibility is the key to a well-run and properly funded predictive maintenance program.

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