The two NFPA documents that have changed the face of infrared thermography over the last few decades are NFPA 70B and NFPA 70E. 70B is the Recommended Practice for Electrical Equipment Maintenance, while 70E is the standard that covers electrical safety in the workplace.
There is no other organization in the world that has had a greater impact on infrared thermography over the last 25 years than the NFPA with the production of these two documents.
Concerning electrical maintenance, an excerpt from the document 70B declares, "a well-administered Electrical Preventative Maintenance program will reduce accidents, save lives, and minimize costly break downs and unplanned shutdowns of production equipment." It further recommends that "routine infrared inspections of energized electrical systems should be performed annually prior to shutdown. More frequent infrared inspections, for example, quarterly or semi-annually, should be performed where warranted by loss experience, installation of new electrical equipment, or changes in environmental, operational, or load conditions."
Although NFPA has no regulatory power, these recommendations were given teeth when they were adopted as a standard by the Occupational Health and Safety Administration (OSHA). OSHA is the main US government agency charged with the enforcement of safety and health legislation in American industry. OSHA has the power and the authority to levy heavy fines on those who do not conform to their adopted or authored standards.
OSHA's adoption of these NFPA recommendations produced a great demand for infrared cameras in the US. Demand increased abroad as
well, as many countries looked to the NFPA standards and adopted some form of them into their own regulations. Thus, there was also a proliferation of infrared camera manufacturers. Companies such as Fluke, known throughout the country for their dependable industrial metering instruments, entered the infrared camera market by buying small existing companies and growing into a major supplier of a number of infrared camera models. Flir and Fluke seem to be the major players in the North American market, with a dozen or so other companies also involved in supplying systems. This increase in sales quantities, coupled with new detector technology, has caused the price of an infrared camera to plunge from $70,000 in the 1980s to under $2,000 today. The rather heavy bulky systems have been transformed into lightweight, small, and hand-held instruments that can be taken easily into any industrial situation.
If you are performing infrared electrical inspections, and you are not following these OSHA adopted standards, you need to familiarize yourself with them and comply.
Figure 1 is an old-style, liquid nitrogen-cooled, two-piece infrared camera system that weighed in excess of 60 pounds. There was no digital technology available in that camera's era, and the image was captured on black-and-white Polaroid film directly from the display. The lack of computer technology also meant that all temperature calculations had to be determined with pencil, paper, and printed calibration curves. The liquid nitrogen had to be replenished every 1.5 hours in order to keep a grey tone image displayed on the screen.
In contrast, Figure 2 is an example of the compactness of today's new cameras. This particular system has the look and feel of a common digital camera, complete with on-screen temperature calculations and color images. It also has the capability of capturing corresponding visible light images, as well as an infrared image in a number of different color pallets.
It must be noted here that although these inexpensive new cameras are lightweight and compact and are advertised to have many functions, they are not always suited to all applications, due to their small detector size and inability to calculate the accurate temperature or temperature difference of many conductors at safe working distances.
(For more information on how to choose the right infrared camera for your application, please refer to the Aug/Sept 2010 issue of Uptime Magazine.)
NFPA 70E, the standard for electrical safety, was first released in 1979, with its greatest impact taking place with the 2000 edition, which defined levels of Personal Protective Equipment (PPE) that must be worn when working within certain distances from live equipment. NFPA Table 130.2 defines the safe working distances from live moveable and stationary equipment. As an example, for energized equipment with moveable parts, you must be at least 10 feet from any energized component with a voltage between 50 - 300 volts. If you are any closer, you are within the arc flash protection boundary, and you must wear extensive PPE, even if you are only performing an infrared thermography inspection. This PPE includes "arc-rated FR shirt & pants or FR coveralls, and arc flash suit selected so that the system arc rating meets the required minimum." It also includes a dual-layer glove that when wearing, you cannot operate most of the compact new cameras.
If you are performing infrared electrical inspections, and you are not following these OSHA adopted standards, you need to familiarize yourself with them and comply. Not only is your company liable for large fines, but the individual technician is also in danger of being fined for violation of these regulations.
This monumental change in the way infrared electrical inspections are performed has spawned a totally new infrared-related industry. There are now a number of companies manufacturing and distributing infrared semitransparent windows for installation in electrical cabinets. They come in many shapes and sizes, as can be seen in Figures 3 and 4.
With these windows in place, no special PPE is required, because as the cabinets do not need to be opened, the technician is not exposed to live circuits. Placed in the proper location, electrical components can be inspected in the "energized" condition as prescribed in NFPA 70E with a 0 hazard risk factor. Both NFPA 70B and NFPA 70E are available on the internet and can be downloaded. If you have difficulty with these regulations and what they mean to your location, there are a number of companies that can be contracted to assist you in implementing these standards, as well as in the placement and installation of infrared windows. This includes most of the window manufacturers themselves.
Wayne Ruddock has been involved in Infrared Thermography and Infrared Thermographic Training since 1979. He is a seasoned veteran of hands-on infrared inspections, giving him the ability to teach real-life thermography. He has been conducting Level 1 and Level 2 training courses throughout the world since 1980. He has written and presented many thermographic papers at conferences over the last 30 years, and he is the author of Basic Infrared Thermography Principles, available at www.mro-zone.com.