What is the Expected Lifespan of Your Office Lighting? Learn about Average Rated Life of Luminaires.

When you’re selecting lighting for your office, shop, or home, one key factor often pops up: What is the expected lifespan of these light fittings? In the construction industry,  this is what is referred to as Average rated life. It’s the indication of how long your lights will work before they start to fade. But what does it really mean, how is it measured, and why does it matter for your next project? Let’s shed some light on the rated life of luminaires and help you specify light fixtures that deliver lasting performance.

What Is Average Rated Life?

Rated Life or Rated Service Life translates into how long a luminaire will perform before its brightness drops below a useful level. For LEDs, it’s not about when they “burn out” like old fluorescent lamps; it’s about how long they keep delivering enough light for your space. Measured in hours, it’s an industry benchmark of durability and efficiency, guiding you on maintenance, costs, and sustainability. 

Most LEDs have an Average Rated Life (ARL) of 50,000 hours. The most common metric is L70, meaning the luminaire will last until its light output dips to 70% of its original brightness.  For example, a rated life of 50,000 hours at L70 means your light fitting should emit light at least 70% as bright as day one after 50,000 hours of use.
These days, lighting manufacturers can produce fittings with L80 (80% brightness) or even L90 (90%).

How Is Rated Life Measured?

Lighting manufacturers test luminaires under controlled conditions, following standards like IES LM-80 and TM-21, set by the Illuminating Engineering Society. These are globally recognised standards.  

• LM-80 Testing: LED chips are run for thousands of hours (usually between 6,000–10,000 hours) at different temperatures. Light output and colour stability are measured over time to see how they degrade.
• TM-21 Projection: Using that data, engineers predict how long the LED will last before hitting L70, L80, or L90. 

The requirements for luminaire performance and environmental footprint are standardised by the international standard  BS EN 62722-1 and BS EN 62722.

What Affects Rated Life?

The choice of rated service life index has a significant impact on the maintenance factor to be specified in the lighting planning stage.

• Usage: A light on 24/7 (like in a hospital) hits 50,000 hours in about 5.7 years. If its used 8 hours a day (think offices) that's over 17 years longer.
• Heat: LEDs don't like getting hot. Poor ventilation or high ambient temperatures can shave years off rated life. 
• Power Quality: Flickery drivers or voltage spikes can put additional stress on the components. High-quality drivers keep performance steady.
• Dimming: Dimming often extends lifespan of the lighting by reducing heat and power strain, especially with smart systems like DALI-2 or PoE.

Significant Impact on the Maintenance Factor

• Cost Savings: A Longer life means fewer replacements and less maintenance. A 50,000-hour luminaire could outlast multiple cheaper alternatives, saving you cash long-term.
• Sustainability: Fewer swaps mean less waste. 
• Performance: Consistent light levels keep your space functional, visually comfortable and inviting. Higher L-ratings (like L80 or L90) maintain quality longer.

Rated Life in Action: What to Expect

Let’s break it down. A luminaire rated at 50,000 hours L70:

Add dimming or cooler conditions, and you might stretch it further. But here’s the spoiler alert: rated life is an average, not a guarantee. Quality matters, and cheap fixtures might not hit the mark. We make sure that the products we are putting forward for your project is built to last.

Why Choose 299 Lighting?

• Top quality LEDs: High-quality chips with proven LM-80 data.
• Smart Design: We only put forward tried and tested products and take care of details like heat sinks and quality drivers.
• Flexibility: We will pair the light fittings with DALI, DMX, or PoE for dimming that extends life and cuts energy use.

Light Up the Long Term

Rated life is your roadmap to smarter lighting choices. Whether you’re fitting out a modern office or a large commercial space, understanding how long your luminaires will last helps you plan for efficiency, ROI, and sustainability. Our team’s here to guide you, get in touch today, and let’s light your space for the long haul.