Flood Lighting Design And Illumination

What is Flood Light Luminaire?

Flood light luminaire is the luminaire that covers wide range surface with broad angle of projection.

What is the main difference between Flood Light Luminaire and Road Light Luminaire?

The main difference between the flood light and the other luminaire used in road lighting is the former aiming direction with respect to the light intensity axis. That means, the road light luminaire is always aimed at a particular direction on the road surface spot wise. But flood light covers the wide range surface of the aimed object like buildings, hording etc and it is defined to a proper mounting position. Whereas road light luminaire cannot cover wide range of road surface area.

What are the Photometric Characteristics of Food Light Luminaire to Design?

The photometric data of the flood light is given below.

  1. Peak intensity
  2. Beam spread
  3. Beam efficiency
  4. Luminous intensity
  5. Half plane divergence

What is Peak Intensity of a Flood Light Luminaire?

Peak intensity is the maximum intensity of the flood light in the direction of the intensity axis. It is generally specified in candela per 1000 lumens of the lamp Lux.

What is Beam Spread of Flood Light Luminaire?

Beam spread is defined as the angle over which the luminous intensity drops to a stated percentage (usually 50 to 100 %) of its peak value.

intensity distribution diagram
Here the beam spread is 0o to β1 or 00 to β2.
The beam spread of a floodlight is also known as beam width or beam spread angle.

  • Generally rotationally symmetric luminous intensity distribution is used for the flood light luminaire.
  • In Rotationally symmetric luminous intensity distribution the intensity remains unchanged through the same beam spread angle considered at both sides of the intensity axis.
  • For example, if the beam spread is within 50 degree, then 25 degree will be at both sides of the intensity axis. Through 25 degree in both sides of the intensity axis, intensity is constant.
  • Again for asymmetric distribution, two figures are provided along with the luminaire. As an example, 60/240, for the beams. From the intensity axis up to 5 degree in one side and up to 24 degree in another side, the intensity falls from 100 % to 50 %.

Beam Spread angle is broadly classified into three categories,

  1. Narrow Beam: when beam spread angle ≤ 20 degree
  2. Medium Beam: when beam spread angle ranges from 20 degree to 40 degree
  3. Wide beam: when beam spread angle ≥ 40 degree

What is Beam Efficiency of Flood Light Luminaire?

The beam efficiency is known as light output ratio. It is defined as the ratio of the beam flux to the lamp flux. Light output ratio for the beam is calculated at 10% and 50% of the peak intensity. Beam flux is related to the luminaire output flux whereas lamp flux means the luminous flux produced by the lamp in this luminaire.

Where are full Characteristics of a Flood Light Luminaire obtained from?

Generally two luminous intensity diagrams are provided along with the flood light luminaire. One diagram shows the two plane symmetry of intensity variation of the flood light luminaire and another one shows the isocandela diagram. Iso candela diagram means the intensity distribution of the luminaire of flood light with respect to its surface of light exit.
The beam spread angle of a flood light luminaire serves a useful guide to flood light luminaire selection, whereas Iso candela diagram or intensity distribution of the luminaire gives detailed characteristics of this luminaire.
Intensity Distribution Diagram of flood light luminaire is shown below.
intensity distribution diagram
As per the figure, 0 to β1 is the half peak side angle. This angle is between the direction of maximum luminous intensity and the direction in which the flood light has the luminous intensity of 50 % of max in specified half plane.

What is the Half Plane Divergence of Flood Light Luminaire?

It is the angular extension in all directions of a beam at both sides of the intensity axis.
half plane divergence of flood light luminaire
As per the asymmetric intensity distribution diagram of luminaire, the half peak divergence is β1 + β2.

What is the Inner Beam of a Flood Light Luminaire?

It is the solid angle consisting of intensity greater than or equal to 50% of the maximum intensity.

What is the Outer Beam of Flood Light?

It is the solid angle containing all directions of luminous intensity greater or equal to 10% of the maximum intensity.

What are the types of the Flood Light as per Luminous Intensity Distribution?

  1. Rotational symmetry
  2. Symmetry above two plane
  3. Symmetry about single plane
  4. Asymmetry

types of the flood light as per luminous intensity distribution

What are the types of the Flood Light as per NEMA recommended Beam Spread Angle?

  1. Type 1 : beam spread angle ranges from 10 degree to 18 degree
  2. Type 2 : beam spread angle ranges from 18 degree to 29 degree
  3. Type 3 : beam spread angle ranges from 29 degree to 45 degree
  4. Type 4 : beam spread angle ranges from 45 degree to 70 degree
  5. Type 5 : beam spread angle ranges from 70 degree to 100 degree
  6. Type 6 : beam spread angle ranges from 100 degree to 130 degree
  7. Type 7 : beam spread angle ranges beyond 130 degree

What are the main Objectives of Flood Lighting Designs?

  1. Safety and security
  2. Amenity
  3. Decoration
  4. Commercial interior
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