We are all concerned about safety and dangerous Arc-Flash occurring. We take many safety precautions to avoid these scenarios from occuring. One primary method to reduce this hazard and possibly eliminate danger and harm to personnel is to establish an installation program utilizing thermal windows. These arc-resistant infrared windows allow thermal cameras to be used without exposing personnel to live equipment. Statistically, most Arc-Flash danger occurs while personnel are working close to electrical panels with the panel door opened. Although the National Fire Protection Association (NFPA) has established the NFPA 70E CAT Safety Ratings’ Standard, which established safety workplace regulations for clothing and safety personal protection equipment, Thermal Windows assist in meeting compliance while maintaining personnel safety and continuing plant operations without interruption. This certainly can be thought of as meeting compliance requirements for safety without compromising equipment or personnel. We eliminate much risk of a hazardous condition when utilizing a Thermal Window as part of the installation.

Arc-flash Stats and Figures

• The arc flash itself can achieve temperatures in excess of 35,000 °F (Source: National Fire Protection Association)
• Five to ten (5 to 10) arc flash explosions occur every day in the US (Source: National Fire Protection Association)
• Approximately 2,000 workers will be admitted to hospital burn units this year due to thermal burns from arc flash or arc blast accidents (Source: CapShell, Inc.)

Thermal Cameras for Police and Security Applications

IR windows allow thermal cameras to be used for safer electrical inspections while reducing exposure to hazards and personnel danger. As stated in NFPA 70E, the Electrical Safety Standard in the workplace, all electrical locations are categorized into CAT I, II, III, and IV. These Cat ratings classify the risk and hazard possibility for danger in all electrical locations. In order to be in Compliance with this standard, appropriate clothing and equipment, PPE-Personal Protection Equipment, is required in order to enter the selected area and proceed with any testing or evaluations. With the use of installed Thermal IR Windows, you will be able to perform safer and more efficient Low and High Voltage Electrical Inspections without exposing personnel to any increased risk.

The primary safety evaluation is done behind Electrical Equipment Room doors. Arc flash accidents can cost the user many millions of dollars. Increased insurance costs, personnel danger, loss of life, loss of production, damaged equipment, facility repair and replacement costs may only be some problems. The most important being danger and hazard to personnel. Agencies such as OSHA (or other occupational safety bodies around the world) may issue fines and punishments that may never be recoverable. IR windows add an extra level of protection in order to avoid the tragedy of harm to life and limb due to an arc-flash incident that may be preventable.

NFPA 70E

The standard for electrical safety in the workplace.

CAT Ratings

CATIV - Three-phase at utility connection, any outdoor conductors. Example: overhead line to detached buiding.

CATIII - Three phase distribution including single-phase commercial lighting. Example: bus and feeder in industrial plants.

CATII - Single-phase receptable connected loads. Example: outlet and long branch circuits.

CATI - Electronic. Example: Any high-voltage, low-voltage energy source derivced from a high-winding resistance transformer such as the high-voltage section of a copier.

Features To Consider

Intalling and utilizing thermal windows can help add safety to your work environment. Below are common features available today for thermal windows:

• Minimizes time and cost of complying with NFPA 70E (see specification above)
• Optic Diameter
• Viewing Aperture Diameter
• Available Viewing Area
• Arc Flash Testing Certification and Agency
• Crystal or Metal Mesh lens
• Field Of View Calculation
• Security Key Door Latch
• Allows Electrical Inspections in extremely hazardous environments
• Decreases risk of injury due to arc flash incidents
• Perform Visual Inspections on a regular basis
• Allows Thermal Inspections on a regular basis
• Category ratings remain intact following window installation
• Variety of Sizes to match Thermal Cameras
• Ease of installation
• Consider both Indoor & Outdoor use
• Grounding capability for window
• Waterproof Housing meets IP65
• Maximum operating temperature
• Camera compatibility
• Installation method utilizing standard Industry tools
• Window Lock method
• Cover and fastener mechanism
• Operations to Install
• Compatibility with Thermal, Fusion and Wavelength spectrums
• Lifetime Warranty

Complying with NFPA 70E Measurement Positioning for Safety

As described above, NFPA 70E details information as required to efficiently and safely perform Electrical Inspections. These inspections must be made on a regular basis since electrical connections and conductors may be loose, corroded, overheated, under rated or carrying increased load or just in a critical condition where excessive heat becomes a dangerous problem. The temperature rise or differential may be extremely important in maintaining an efficient system and its components. By utilizing a Thermal Camera and installed Thermal Window many possible problems may be observed and corrected before any dangerous situation exists. If the location of these Electrical components, transformers, switchgear, circuit breakers, relays, timers and all components is in an area that requires PPE that is not readily or quickly available, an IR Window allows the technician to perform the inspection and provide the results.

Below are two cameras being used to measure electrical and safety conditions on the other side of the door. This enable the operator to comply with NFPA 70E requirements and still continue their thermography program for safety. Note the two different windows being used. The use of the windows allows the testing to be continued without special safety clothing or apparatus. This saves much time and cost while the operation continues.

Figure 1 - IR Window Inspection

Figure 2 - IR Window and Thermal Camera

Open Diameter and Available Viewing Area

Understanding the difference between “Optic Diameter” and “Available Area” gives the thermographer a measure of how much infrared energy is passing through the window. The more energy, the better the reading. Based on experience and testing evaluation, using a crystal IR Window means that the entire area is available for infrared transmission for optimum repeatability and results. While a mesh grid may have a larger “Optic Diameter” the grid itself may block the total IR signal. This may mean that that the amount of radiation available to the camera can be significantly reduced and the signal may be irregular. Crystal lenses support short, mid, and long wave IR cameras, visual inspections, and fusion technology. This will allow with integrated lenses to capture video documentation.

Arc-Flash Testing and Certification Agency

Although the window provides protection against obvious “behind the door” dangers, a testing agency evaluates each product and certifies that it meets extreme standards for Arc-Flash incidents. Please confirm that the window of choice has been certified and tested to high current arc-flash conditions which protect personnel. Arc Flash Testing, IEC 62271-200 (KEMA) is an industry standard for 5kV, 63kA for 30 Cycles at 60Hz. Confirm that your window meets or exceeds these testing results.

Ease of Installation

Some Windows have been designed for installation using a standard industry Punch. These standard and readily available knockout punches may make the installation function slightly easier. If the Window has this installation feature, the appropriate Punch is specified by part number in the datasheet and manual included with the window chosen. This may be an advantage when considering installation. The attached link describes a typical installation of a thermal window.

Security Key Door Latch

In order to include additional security and limit unauthorized access, some windows are supplied with a lockable Door Latch. If you prefer this feature, a key is supplied for security. Please review the specifications if this feature is important.

Field Of View Calculation - In order to calculate the size of the viewed image through the Thermal Window, use the approximate Field of View diagram calculation diagram as shown.

Sensitivity is commonly shown as deg C and mK (millikelvins). The sensitivity specification usually is accompanied with a calibrated temperature, i.e. the sensitivity may read: .10deg C @ 30 deg C target temperature (or ambient temperature). Please note that a lower sensitivity will increase the detail of displayed temperature and indicate greater minute differentials in the evaluated components. This display may result in product color variations, product detail specifics and more exacting temperature results. Considering Cameras with a varied range of sensitivities will be based on specific applications and industry needs.

Thermal Windows Summary

It is important to understand that measurements outside of enclosures or rooms may be an important option. Using Thermal Camera IR Windows offers an opportunity to Electrical Inspection Teams as well as to Consultants, Engineers, Maintenance Personnel, Management and Facility Managers another opportunity to Measure and Evaluate without entering a dangerous electrical location. Please call one of our Certified Thermographers for a complete discussion and appropriate solution to your specific application.