Frequently Asked Questions
What is the service life of a Stela luminaire?
The service life is 100,000 hours (25 years based on 4,000 hours per annum).
What is the lumen depreciation at 100,000 hours?
15% depreciation is expected (85% lumen maintenance).
What is the colour temperature and colour rendering index?
For road lighting, the most efficient source is 5700K temperature with a CRI of 75.
What is the service life of the LED driver?
The service life is 100,000 hours (25 years based on 4,000 hours per annum).
Can I change an LED if one fails?
The likelihood of an LED failing is extremely small over the service life of Stela since the operating life for an individual LED is in fact more than 200,000 hours. If one does fail however, since every LED has an identical footprint and is not being used as a directional light source, there is no impact on uniformity, only a reduction in light level in proportion to the total LEDs fitted, so changing an LED should never be required.
Can I change a LED driver if it fails?
The LED driver is accessible in the separate gear compartment and simple to replace in the unlikely event that this proves necessary.
What is the cleaning cycle for Stela?
The cleaning cycle will depend on the environmental conditions of the installation; however for the majority of road lighting applications, the cleaning cycle can be up to six years.
What maintenance factors should I use for Stela?
Remembering that Stela has 100,000 hour service life, the user must think about what lighting level needs to be achieved at the end of service life or at the point where it is planned to change the luminaire.
If the user selects Maintained Illuminance at 25 years, the following would apply:
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Lumen Maintenance =
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0.85
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Maintenance Factor =
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0.93 (Low Pollution)
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0.93 (Medium Pollution)
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0.87 (High Pollution)
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What is the power consumption of Stela?
The table below shows data for Stela at 230V, 50Hz Ta +10 Celsius. Typical Power Factor 0.95.

What are the UMSUG* Codes for Stela?
Unmetered Supplies Operational Charge Codes are available on the Elexon website.
Click here to download the latest spreadsheet [.xls].
* UMSUG (Unmetered Supplies User Group) is a committee of the UK wholesale electricity market managers.
Stela product information