10.2 Lighting

Question 1

Interior lighting can be categorised as

Answer 1

general, localised or local

Question 2

General

lighting

Answer 2

Provides uniform illumination over the whole working area

and does not limit positioning of the work.

Question 3

Localised

lighting

Answer 3

Provides different levels of illumination in different parts of
the same working area. It matches the level of illumination
to the needs of specific tasks.

Question 4

Local

lighting

Answer 4

Usually a combination of background lighting and a
luminaire close to the actual work area. Used when:
 a high level of illumination is needed in a small area
 flexible directional lighting is required for different tasks
at a workstation
 general lighting is unnecessary or impossible to install
because of the layout of the work area

Question 5

Lighting hazards may originate from: 4

Answer 5

 Lighting effects.
 Incorrect lighting design.
 Improper lighting installation, maintenance, replacement and disposal.
 Improper selection of emergency lighting.

Question 6

Hazards from lighting effects

Answer 6

Glare
Colour effects
Stroboscopic effects 
Flicker
Veiling reflections 
Radiation

Question 7

Field measurements of illuminance may be required for the following reasons: 3

Answer 7

 To establish whether a new installation has achieved the design specification.
 To establish whether an installation meets a desired criterion.
 For trouble-shooting in identifying the causes of complaints about the lighting.

Question 8

Candela

Answer 8

The candela is the SI (international) unit of luminous intensity. It is equal to one
lumen per steradian.

Historically one candela was the amount of visible light emitted by one standard
candle in a given direction.

Question 9

Lumen (Im)

Answer 9

The lumen is the SI unit of luminous flux, used in describing a quantity of light
emitted by a source or received by a surface.

The lumen was created as the measure of total luminous power (i.e. visible light
power) as defined by a set of ideal human eyes.

One lumen is defined as one candela-steradian (cd sr), or the amount of light power
needed to send 1 candela of light in all directions.

Question 10

Lux (lx)

Answer 10

The  lux  (lx)  is  the  SI  unit  of  illuminance,  or  luminous  flux  per  unit  area.  It  is  a 
measure of the intensity, as perceived by the human eye, of light that hits or passes 
through a surface. 

One lux is equal to one lumen per square metre.