Infrared Inspection Windows: The Smarter Way to See Inside

Infrared windows offer a safe option for electrical inspection and come in a range of formats—from infrared-transmitting lenses to lens-free options. Each approach has its advantages.

"Hidden" doesn't always mean invisible—sometimes, it just means out of reach behind an electrical panel. Electrical failures rarely happen instantly; they build up over time, often leaving behind subtle warning signs in the form of excessive heat. The challenge? Safely detecting these issues without exposing workers to live electrical components or requiring lengthy shutdowns.

Infrared (IR) inspection windows provide a simple but effective solution, allowing thermographers to inspect energized electrical systems without opening the enclosure. This not only minimizes arc flash risks but also significantly reduces inspection time, making thermal monitoring a more practical part of routine maintenance.

But not all IR windows are created equal. From crystal-based designs offering optical clarity to rugged polymer windows built for extreme environments—and even lens-free inspection ports that remove the need for a transmission window entirely—each approach has its own advantages.

Beyond the Panel: The Advantages of IR Windows

Every minute counts in industrial maintenance. Traditional electrical inspections require removing panel covers, suiting up in heavy PPE, and working under strict safety protocols. IR windows change the equation by allowing fast, frequent, and safer inspections.

Key advantages include:

  • Reduced PPE requirements – Inspect energized equipment without direct exposure, minimizing the need for arc flash-rated suits.
  • Consistent data collection – No need to adjust camera settings for variable IR window transmission rates.
  • Compliance made easier – Helps companies meet NFPA 70B and NFPA 70E guidelines for electrical safety while supporting predictive maintenance initiatives.

The question isn’t whether to install IR windows—it’s which type best fits your facility’s needs.

Crystal IR Windows

High-Precision Thermal and Visual Inspections

Crystal-based IR windows, such as FLIR’s IRC-Series, are engineered for both thermal and visual inspections, offering unparalleled optical clarity. Made from calcium fluoride (CaF₂), these windows naturally resist moisture absorption, preventing degradation over time and ensuring consistent infrared transmission.

The lenses are grown from a single crystal and precisely sliced into wafers using a process similar to solar cell manufacturing. Their round shape allows for quick, secure installation with common electrician’s tools like hole punches or drills—eliminating the need for complex mounting procedures.

Unlike Germanium-based alternatives, crystal IR windows transmit short, mid, and longwave infrared radiation while also allowing visible light to pass through. This dual capability enables technicians to perform both thermal imaging and direct visual inspections, making them ideal for applications where assessing electrical connections and components with the naked eye is just as critical as capturing thermal data.

When to choose crystal IR windows:

  • When thermal and visual inspections are equally important.
  • When you need the window to work well with all infrared camera types and lenses.
  • When environmental conditions make open ports unsuitable for the installation location (e.g., outdoor environments where exposure to moisture, dust, or debris is a concern).
  • When an unobstructed view is essential, and mesh backing could interfere with visibility or distort temperature readings.
  • When rapid installation is essential—FLIR’s IRC-Series requires only a single punched hole, unlike other designs that demand precise alignment of multiple holes, reducing installation time and complexity.
Thermal image taken through a FLIR IRC-Series window.

Polymer IR Windows

Built for Durability

For facilities that prioritize ruggedness and coverage over optical clarity, polymer-based IR windows provide a more robust solution. The FLIR IRW-xPC/xPS series features an impact-resistant polymer window that can withstand harsh conditions, including corrosive environments.

Unlike crystal-based alternatives, polymer IR windows offer:

  • Shatter resistance: No risk of cracking under mechanical stress.
  • A larger field of view: The rectangular design provides more visibility per inspection point.
  • Resistance to environmental degradation: – Stable under extreme temperatures, humidity, and vibration.

This makes polymer IR windows an ideal choice for industries such as maritime, mining, and heavy manufacturing, where inspections must be both frequent and highly durable.

Lens-Free Inspection Ports

A Minimalist Approach

Not every electrical enclosure requires a window.

The FLIR IRP-1 Inspection Port takes a different approach by eliminating the need for an IR-transmissive material entirely. Instead, it provides a secure access point designed for use with a FLIR 80° lens, allowing thermographers to quickly scan electrical components without adjusting for window transmission loss.

  • No lens, no transmission loss – Ensures accurate thermal readings without correction.
  • Faster inspections – No need to account for IR window coatings or materials.
  • Cost-effective installation – Reduces upfront investment while maintaining NFPA 70B and NFPA 70E compliance.

For facilities prioritizing speed, accuracy, and minimal intervention, the IRP-1 is a straightforward alternative to traditional IR windows.

Inspect Indoor Electrical Cabinets Safely with FLIR IRP-1

Meet the FLIR IRP-1: a lens-free inspection port designed specifically for use with 80° infrared lenses mounted on FLIR thermal imaging cameras.

Choosing the Right IR Window for Your Facility

Infrared windows aren’t just about compliance—they’re about working smarter, faster, and safer. Choosing the right solution depends on what’s most important to your operation.

For high-precision thermal and visual inspections: Crystal IR windows (IRC-Series). For durability in high-impact environments: Polymer IR windows (IRW-xPC/xPS). For fast, low-maintenance thermal monitoring: Lens-free inspection ports (IRP-1).

Safety Considerations for Each Window

  • Ensure the window or port is rated for the equipment and environment intended.
  • If installed as “aftermarket”, an electrical safety authority is typically needed to validate the equipment before re-energizing.
  • Cover must be in place in between thermography scans.
  • If a window gets damaged it should be replaced.

By integrating IR windows into an electrical maintenance program, teams can detect failures early, reduce unplanned downtime, and enhance worker safety—all while making routine inspections more efficient.