Lighting failures in hot environments are most frequently caused by thermal overload of internal components. Heat accelerates the degradation of LED chips, drivers, and optical materials, causing fixtures to fail sooner than their lifespan suggests. This is particularly true for industrial environments such as steel mills, foundries, and drying plants, where ambient temperatures can structurally exceed 50°C.
In this article, we answer the most frequently asked questions about lighting failures in hot environments, from the causes to the correct preventive measures.
Why do lights fail sooner at high temperatures?
Heat is the greatest enemy of electronic components. At higher ambient temperatures, the internal temperature of a luminaire also rises, leading to accelerated aging of the components. Every 10°C increase can roughly halve the lifespan of an LED driver. This makes thermal management a critical factor in lighting design for hot industrial environments.
Standard luminaires are typically designed for ambient temperatures up to 25°C or 40°C. As soon as they are used in an environment with continuous heat, they operate structurally outside their specifications. The result is not always an immediate failure, but a creeping deterioration: light output drops, color rendering worsens, and eventually the system fails at the moment you can least afford it.
Which components fail first in extreme heat?
In an LED luminaire, three components are particularly vulnerable to high temperatures: the LED driver, the LED chip itself, and the optical elements. The driver, which regulates the current, contains electrolytic capacitors that degrade rapidly when exposed to heat. The LED chip loses light output as the junction temperature rises. And plastic optical lenses can discolor or deform upon prolonged exposure to high temperatures.
- LED driver Electrolytic capacitors dry out in heat, leading to unstable power delivery or complete failure.
- LED chip High junction temperatures cause light degradation and a shortened lifespan.
- Optical lenses: Plastic lenses discolor in extreme heat, which reduces light transmission.
- Housing and seals: Rubber gaskets and silicone compounds can dry out and crack, compromising IP protection.
- Thermal interface material: Connections between the LED module and heat sink can become loose, impairing heat dissipation.
For luminaires designed for High-temperature lighting Are these components intentionally selected for higher temperature classes and are the internal thermal paths carefully designed to dissipate heat effectively.
What is the difference between ambient temperature and junction temperature?
The ambient temperature is the temperature of the air surrounding the luminaire. The junction temperature is the temperature at the active semiconductor point within the LED chip itself. This difference is crucial: even in a 40°C environment, the junction temperature can rise to 80°C or higher, depending on the thermal design of the luminaire.
A well-designed luminaire minimizes the temperature difference between the ambient environment and the junction via an efficient heat sink, the correct current setting, and a well-thought-out thermal path. Manufacturers specify the maximum junction temperature, often referred to as Tj max, and a reliable luminaire structurally operates well below that limit, even at the highest expected ambient temperature.
In practice, this means that a luminaire with a maximum Tj of 125°C and poor cooling can already run into trouble at an ambient temperature of 60°C, whereas a luminaire with a good thermal design can handle the same environment without any issues.
How do you recognize a malfunction caused by heat?
Thermal faults have a recognizable pattern. They often occur after prolonged operation, worsen at higher outside temperatures or during the summer months, and sometimes disappear temporarily when the system cools down. The latter makes them difficult to diagnose: the fixture appears to work normally upon inspection.
Concrete signs indicating a heat-related malfunction:
- Valves that fail after a few hours of operation and restart again after cooling down.
- Visible discoloration or deformation of the housing or lenses.
- A strong, unusual odor indicating overheated electronics or rubber.
- Light flickering that increases as the ambient temperature rises.
- Measurable loss of light compared to the original light output, with no other discernible cause.
When in doubt, a thermographic measurement is an effective method for identifying hotspots in a fixture or installation without the need to take the installation out of service.
Which IP and temperature classes are required for hot industrial environments?
For industrial environments with high temperatures, specific requirements apply to both the degree of protection and the temperature resistance of luminaires. The IP rating determines the protection against dust and moisture, while the Ta value (ambient temperature rating) indicates the ambient temperature up to which a luminaire is certified for reliable use.
In environments with dust, splashing water, or steam, a minimum of IP65 is generally required. In environments with direct water jets or immersion, higher ratings apply. You can read more about the meaning of these ratings on the IP and IK rating page.
Regarding temperature classes: standard fixtures are often certified up to a Ta of 40°C or 50°C. For environments such as drying installations, steel mills, or climate chambers, fixtures are needed that are certified for Ta values of 60°C, 80°C, or even higher. In extreme cases, such as when exposed to infrared radiation in steel production, fixtures are required that can withstand ambient temperatures up to 120°C.
How do you prevent lighting failures in hot environments?
Prevention starts with the right product selection. A luminaire designed and certified for the actual ambient temperature forms the basis. After that, installation, positioning, and maintenance determine long-term reliability.
Practical measures to prevent disruptions:
- Select fixtures with a Ta rating that comfortably exceeds the maximum ambient temperature, rather than just barely meeting it.
- Ensure sufficient clearance around the luminaire for natural air circulation.
- Avoid mounting directly above heat sources such as ovens, dryers, or combustion installations, unless the fixture is specifically designed for that purpose.
- Schedule periodic inspections to check seals, heat sinks, and electrical connections.
- Use luminaires with passive cooling in environments where active cooling (fans) quickly clogs due to dust or vapors.
A good lighting specialist performs a thermal analysis of the installation environment in advance, so that the fixture selection and positioning are tailored to the actual operating conditions.
Practical example: Rockwool Croatia
In the Rockwool factory in Zajci, Croatia, the ambient temperature in production rises above 110 °C, with additional heat load from infrared radiation. Standard LED lighting, and even many heat-resistant versions, failed under these conditions. In summer, with outdoor temperatures approaching 40 °C, the heat also led to LED driver failures. JEL supplied more than 50 Barracuda HT, more than 20 Snapper HT and more than 30 Linear HT. The drivers must not get warmer than 50 °C; their positioning and cooling were designed and tested separately, away from the hot production zones. The installation achieves more than 100 lux on the shop floor.
The failures here had two sources: the heat and radiation around the luminaire, and the temperature around the driver. Looking only at the ambient temperature at the light source misses that second source.
When analysing failures in a hot environment, it therefore pays to assess the luminaire and the driver separately: where is the light source, where are the electronics, and what temperature prevails at each of those locations, including in the warmest period of the year.
Read more about the Rockwool Croatia project
How JEL Products Helps Provide Lighting in Hot Environments
JEL Products supplies LED fixtures specifically designed for the most extreme thermal conditions. The Orca and Barracuda high-temperature floodlights are suitable for continuous use at ambient temperatures up to 120°C and can withstand direct exposure to infrared radiation, such as in steel mills and foundries.
Specifically, JEL Products offers the following:
- Luminaires with specified Ta values for extreme environments, including climate chambers: from -45°C, and with the HT line up to +120°C.
- Fully closed enclosures with passive cooling, suitable for dusty and vapor-laden environments.
- Thermal analysis and lighting design as part of the consultancy process.
- Support from engineering to installation and commissioning, including maintenance.
- ISO 9001 and VCA certified working method for projects in heavy industry.
Are you dealing with lighting failures in a hot environment, or do you want to know which fixtures are suitable for your specific situation? Then contact us via the JEL Products Contact Page for a no-obligation consultation.