Lighting of construction sites

[edit] Introduction

In order that construction work can continue effectively and safely in periods of insufficient natural light, it is important that a site is fitted with suitable artificial lighting. Lighting can be used internally for general movement and working on the site itself, externally for illuminating entry, storage and circulation areas, and can also be an effective form of deterrent for trespassers.

There are a wide range of lamps available, from simple tungsten filament lamps to tungsten halogen and discharge lamps. Site lighting is generally run off mains electricity at a voltage of 230 V, rather than through the use of generators. Sometimes it can be necessary to reduce the voltage to 110 V.

[edit] Lighting plan

For an appropriate lighting plan to be drawn up, the types of activity that will be likely to require lighting need to be specified. These activities can then be given an illumination target (with the unit being lux). Lamps are often given a measurement in lumens (lm), which is the total quantity of visible light emitted. One lux is one lumen per square metre.

Examples of recommended minimum target values for building activities include:

External lighting:

Circulation: 10 lx
Materials handling: 10 lx

Internal lighting:

Circulation: 5 lx
Working areas: 15 lx
Concreting: 50 lx
Carpentry and joinery: 100 lx
Bricklaying and plastering: 100 lx
Painting and decorating: 200 lx
Site offices: 200 lx
Drawing board positions: 300 lx

While manufacturers will often specify the best arrangement for lamps according to required use, it is common practice to plan for at least twice the recommended target values. This is because lamps in use can be subject to deterioration, dirt or other conditions that reduce their performance.

It is possible to calculate the required lumens for a particular need with the following equation:

Total lumens required = area to be illuminated (m2) x target value (lx) / Utilisation factor

Where the utilisation factor is 0.23.

Once the lamp type has been chosen, the required number can be calculated with the following equation:

No. of lamps required = total lumens required / lumen output of lamp

[edit] Site arrangement

Lighting can be arranged on site in a static formation, where lamps are fixed to support poles, masts or items of plant such as scaffolding and tower cranes, or, it can be arranged locally, as and where work is progressing, by the use of moveable supports or being hand-held with trailing leads.

Walkways are often illuminated by bulkhead lamps on standard mains voltage. Bulkhead lamps have a die-cast aluminium alloy body together with a vandal-resistant translucent polycarbonate diffuser.

To illuminate general working areas, festoon (overhead) lighting can be suspended from grids at regular spacings. These are usually tungsten filament bulbs, and both cable and lampholders must be appropriately weather-resistant.

The arrangement must be such that visual intrusion and light spillage are kept to a minimum, particularly in close proximity to residential properties and busy roads where it may cause nuisance or distraction. Where necessary, lighting should be provided to site boundaries to ensure the safety of passing pedestrians.

For more information, see How to work safely on a construction site in the dark.