For small retail owners, facility managers, and security-conscious operators, lighting is not just a utility—it is a 24/7 operational necessity. Whether it is illuminating a retail floor for overnight restocking or maintaining visibility for high-definition security cameras, "always-on" lighting presents a unique set of technical and financial challenges.
In a marathon use case (8,760 hours per year), the difference between a "budget" fixture and a professional-grade LED high bay is measured in more than just lumens; it is measured in thermal stability, driver longevity, and total cost of ownership (TCO). We have analyzed the data and simulated real-world scenarios to explain why continuous operation demands a specific engineering approach.
The Physics of Marathon Lighting: Heat is the Enemy
When a light runs 24/7, it reaches a state of "thermal equilibrium." Unlike a garage light that is on for four hours and then cools down, an always-on fixture must dissipate heat continuously. If the thermal management system is inadequate, the internal components—specifically the LED chips and the driver—will degrade at an accelerated rate.
According to the IES LM-80-21 Standard (Lumen Maintenance Testing), LED chips are tested at specific temperatures to measure their light decay over time. For professional-grade fixtures, we look for data that supports an $L_{70}$ rating of at least 50,000 to 60,000 hours. This means that after approximately seven years of 24/7 use, the fixture will still produce 70% of its initial light output.
The Role of the Heatsink
To maintain this lifespan, the heatsink must keep the LED junction temperature below critical thresholds. High-quality fixtures typically utilize cold-forged aluminum or high-purity die-cast aluminum. Cold-forged aluminum offers superior thermal conductivity compared to standard alloys, allowing for a more compact "UFO" design without sacrificing cooling capacity. A rule of thumb for 24/7 reliability is that the heatsink temperature should not exceed 85°C (185°F) at the reference point when the ambient temperature is 40°C (104°F).
The "Brain" of the Fixture: Why Drivers Fail First
In continuous operation, the LED driver (the power supply) is statistically more likely to fail before the LED chips themselves. This is due to the stress on electrolytic capacitors and other heat-sensitive components within the driver housing.
For 24/7 applications, we recommend fixtures equipped with constant-current drivers that feature:
- Wide Input Voltage Range: Support for 120-277V AC ensures the fixture can handle the voltage fluctuations common in small retail or industrial areas.
- Surge Protection: A built-in surge protector (rated for 6kV to 10kV) is essential to defend against "dirty power" and grid spikes that occur during 24/7 operation.
- FCC Part 15 Compliance: As specified by the FCC Part 15 (EMI Regulations), drivers must limit electromagnetic interference (EMI). Low-quality drivers often emit noise that can interfere with wireless security cameras or point-of-sale (POS) systems.
Financial Reality: A 24/7 Simulation
To demonstrate the impact of choosing high-efficacy LEDs over legacy systems (like Metal Halide) for round-the-clock use, we simulated a 24/7 retail scenario.
The Scenario:
- Space: 8,000 sq. ft. facility.
- Fixture Count: 30 units.
- Operation: 8,760 hours/year (24/7).
- Electricity Rate: $0.16/kWh.
| Metric | Legacy 400W Metal Halide | High-Efficacy 150W LED |
|---|---|---|
| Annual Energy Cost | $19,272 | $6,321 |
| Annual Maintenance | $3,811 | $0 |
| HVAC Cooling Credit | $0 | $668 (Savings) |
| HVAC Heating Penalty | $0 | $965 (Cost) |
| Total Annual Opex | $23,083 | $6,618 |
| Net Annual Savings | -- | $16,465 |
The "Glass Box" Logic: Our simulation shows that while an LED upgrade might have a higher initial cost, the payback period is approximately 0.29 years (less than 4 months) in a 24/7 environment. The HVAC interactive effect is a crucial nuance: because LEDs generate less waste heat, your air conditioning costs drop (cooling credit), though your heating costs may rise slightly in winter (heating penalty). For most facilities, the energy savings far outweigh the heating trade-off.
Verification and Compliance: The Professional Standard
When selecting a fixture for continuous duty, "trust but verify" is the professional mantra. You should look for three key certifications:
- DLC Premium: The DesignLights Consortium (DLC) Qualified Products List (QPL) is the industry benchmark for energy efficiency. A "DLC Premium" rating often signifies higher efficacy (lumens per watt) and more rigorous testing, which is often a prerequisite for utility rebates.
- UL Listed: Safety is paramount for 24/7 operation. You can verify a product’s safety standing in the UL Solutions Product iQ Database. This ensures the fixture meets the UL 1598 standard for luminaires.
- IP65 Rating: For security lighting in loading docks or unconditioned spaces, an IP65 rating (per IEC 60529) ensures the fixture is dust-tight and protected against water ingress.
Operational Strategy: Intelligent Dimming
One of the most effective ways to extend the life of a 24/7 lighting system is to use 0-10V dimming. Even in "always-on" environments, there are periods of low activity.
By using occupancy sensors or scheduled controls to dim the lights to 70% or 80% during off-peak hours, you significantly reduce the thermal stress on the driver. This "intelligent dimming" can potentially double the operational lifespan of the driver while still providing enough light for security cameras to function. According to the ASHRAE Standard 90.1-2022, automatic lighting controls are increasingly becoming a code requirement for commercial spaces to reduce "Lighting Power Density" (LPD).
How to Choose: The 24/7 Checklist
If you are responsible for a facility that never sleeps, use this checklist to evaluate your next round of high bay fixtures:
- Efficacy: Look for >135 lm/W. Higher efficacy means less heat generated for the same amount of light.
- Thermal Design: Ensure the fixture uses high-grade aluminum. Avoid plastic-heavy designs for 24/7 use.
- Driver Specs: Confirm 6kV+ surge protection and a wide voltage range (120-277V).
- Testing Reports: Ask for the LM-79 report (performance report card) and the TM-21 projection (lifetime estimate).
- Warranty: A 5-year warranty is the industry standard for pro-grade equipment. Ensure the manufacturer has a clear return and support policy.
Summary of Long-Term Value
For small business owners, the transition to high-performance LED UFO lights is a financial imperative. The combination of energy savings, zero maintenance, and utility rebates—which you can find via the DSIRE Database—creates a cash-flow-positive investment almost immediately. By prioritizing thermal management and driver quality, you ensure that your "always-on" lighting remains a reliable asset rather than a recurring maintenance headache.
Safety Disclaimer: This article is for informational purposes only. Electrical installations should always be performed by a licensed professional in accordance with the National Electrical Code (NEC) and local building regulations. Always consult a qualified electrician before modifying your facility's lighting system.