Outdoor luminaires must also maintain hygiene

The following article originates from Lighting Moments, authored by Mr. Li Jing

Outdoor lighting facilities require maintenance. This maintenance not only involves repairing damaged luminaires and their related components but also includes cleaning the luminaires. Cleaning the luminaires and their components (poles, cabinets, etc.) is necessary both to maintain urban environmental hygiene and create a civilized city, and to ensure the basic lighting function of the facilities, which is even closely related to electrical safety.

Figure 1: Spider web under the Luminaire

Ensure basic lighting functionality, mainly reflected in the cleanliness of the luminaire's light-emitting surface and the replacement of relevant optical components. Certain luminaires that direct light upward tend to accumulate dust, leaves, etc., on their light-emitting surfaces, which can impair normal lighting function. As shown in Figure 2, the nightscape/landscape lighting effect of this building is simple and grand, with a low rate of luminaire damage; however, without exception, the upward-facing light source of the cross-star luminaires has "gone blind," emitting almost no light. The reason is that over time, the upward-facing light-emitting surface becomes completely blocked by dust, causing the luminaire to lose part of its lighting function.

Figure 2: Please observe the upward light-emitting part

Whether lighting facilities are tidy is also closely related to facility safety. Dirty facilities, such as those accumulating dust or fallen leaves, can alter electrical clearances and creepage distances, potentially causing arc discharge, damaging the facilities, and even triggering fires.

影响出光的灯具不洁问题，按问题性质，可分为灯罩内的和灯罩外的。灯罩外的不洁问题，主要发生于出光面朝上的灯具，出光面被灰尘或落叶遮蔽。灯罩内的不洁问题，与灯具的IP等级、环境清洁度息息相关。IP等级越低、粉尘污染越严重，灰尘越容易进入灯具并逐步累积，最后遮蔽出光面，影响灯具功能。此外，灯具出光面的老化也是很大的问题。

Figure 3: Lamp cap with dirty light-emitting surface

Street lights primarily provide functional lighting and have strict performance requirements. Street light lamp heads generally face downward, avoiding dust accumulation; however, due to the luminaire's breathing effect, moisture and dust can still enter the lens housing, affecting normal light output. Therefore, cleaning the street light lens is particularly important, typically requiring disassembly of the luminaire to clean or replace the light-emitting surface.

Figure 4: Cleaning the luminaire (photo by Hangzhou Street Light Bureau)

朝上的景观照明灯具要定期清理出光面。尤其是园林景观照明的埋地灯具，容易被落叶覆盖遮挡，起不到照明效果。

那么，室外灯具要以什么样的频率组织清洗？按《照明设施经济运行》（GB/T 29455—2012）的要求，照明设施应每年清洗两次。当然，根据灯具IP等级不同、环境污染程度不同，可以适当增减清洗频率。

Urban lighting design should consider maintainability, including measures to minimize luminaire soiling and reduce cleaning difficulty after soiling. For example, luminaires should be installed as low as possible to avoid high-altitude cleaning operations. Additionally, the light-emitting surface of high-mounted luminaires should avoid ordinary plastic; instead, luminaires with weather-resistant materials such as glass or silicone for the light-emitting surface should be preferred. For luminaires installed with the light-emitting surface facing upward, using self-cleaning luminaires is also a viable method.

Figure 5: Surface-mounted recessed floor light with self-cleaning function