4.0 Planning a Lighting Scheme:

4.1 General

The lighting requirements of any contract are depending upon the layout and scale of the site and the contract's seasonal span. Basically all site requirements can be grouped under three main headings.

4.1 Safety

The facility to be able to move men and materials with special reference to the effective illumination of safety hazards.

Safety lighting provides a basic level of illumination over most areas of the site. Care should be taken to enable stairwells of staircase and scaffolding to be adequately lit, to allow the safe movement between production areas and to all main exit and welfare facilities. The standard of lighting need only be low, in the region of 20 lux.

4.2 Security

The effective illumination of materials storage areas, workshops, site entrances, etc. to deter pilferage and theft during darkness hours.

4.3 Productivity

The illumination of specific areas to meet the particular production requirements make general provision of this level over the entire site prohibitive on economic grounds, both indoors and in the open. Often temporary high light levels in set areas can be beneficially covered by mobile and portable lighting equipment localized to the particular area of requirement.

4.2 Calculation of lighting requirements

Whilst the special problems of construction means that the best laid plans have frequently to be modified, the overall requirement can usually to be established, engineered and costed at the tender stage.

Lamp and light fittings manufacturers normally supply details of the lighting power of their equipment in LUMENS as a unit of measurement. Light strengths are calculated in LUMENS/SO METRE or LUX s it is called.

4.1 Number of Lamps Required

Haven chosen the approximate light level required it is then simple to calculate the number of light fittings on a type necessary to achieve this.

Total lamp = Area (m2) x Target lux required
Lumens required 0.23 (lamp efficiency factor)

Division of the total lumens required by the lumens of the lamp chosen will give the number of lamps required.

4.3 Restricted Mounting Heights

(i) Where for some reasons mounting heights are restricted then a greater number must be used.

Thus for low ceiling corridors and storage areas, festoon lights of bulk head to be installed to give minimal movement lighting. (Festoon lighting being cable with molded 60 watt holders at about 3m centers). For higher levels of lighting the lamp centers can be reduced.

(ii) For lighting open sites, roadways, etc where the lights have to be mounted outside the working area then the following rules of thumb can be applied.

4.4 Open Area

a) for wide lamps such as mercury vapour lamps in a shovel type shade:

 

Thus a 25ft street lamp column can be use to project light across a 75ft road width for even illumination would require a lamp post every 75ft.

b) for tungsten halogen lamps or slight focused mercury and high pressure lamps:

 

c) for excessive areas to be lit from the perimeter, special high focus lights can be obtained and specialist advice sought.

If you have any doubts on your requirements contact our head office.