Lighting

Question 1

What are the general effects of poor lighting?

Answer 1

Irritation of eyes and eyelids

Breakdown of vision

Headaches

Question 2

What types of poor lighting are there?

Answer 2

Disability glare

Discomfort glare

Colour effects

Stroboscopic effects

Strobe

Flicker effects

Veiling reflections

Tunnel effects

Question 3

What is disability glare?

Answer 3

Reduced visibility due to intense light sources in field of view

Generally occurs when light is 0-45 degrees above the horizontal

Question 4

What is discomfort glare?

Answer 4

Sensation of annoyance or pain induced from overly bright light sources.

Generally occurs within 45 degrees from horizontal line through field of view.

Question 5

What are colour effects?

Answer 5

Artificial light or changing sky conditions cause variation in colour

Question 6

What are stroboscopic effects?

Answer 6

Oscillations in light output caused by alternating AC current

Can cause machinery to appear stationary or moving in a different manner

Question 7

What are flicker effects?

Answer 7

Light modulation at lower frequencies of 50 hertz or less.

Causes flicker which can cause discomfort and fatigue

Can cause epileptic seizures in some

Question 8

What are veiling reflections?

Answer 8

High luminance reflections which overlay the detail of the task

Can affect task performance or cause discomfort

Question 9

What is the tunnel effect?

Answer 9

Light at the end of a dark passage

Causes feeling of tiredness repression and lack of concentration

Question 10

What is considered appropriate lighting?

Answer 10

Light at correct intensity

Positioned to give good modelling

Artificial light should not distort colours

Reduction of glare

No interfering stroboscopic effects

Question 11

What are 3 types of lighting?

Answer 11

General

Localised

Local

Question 12

What does regulation 8 of the “workplace (health, safety and welfare) regulations 1992 say about lighting?

Answer 12

That every workplace should have suitable and sufficient lighting

That natural light shall be provided as far as reasonably practicable

Sufficient emergency lighting is provided where needed.

Question 13

What are the main aspects of lighting surveys?

Answer 13

Illuminance levels

Glare and reflections

Daylight factor

Question 14

What should you check on a preliminary walkthrough of a lighting survey?

Answer 14

Floor plans and positions of light sources

Type of work undertaken in survey areas

Subjective assessment of illuminance levels

Serviceability of luminaires

Suitability of lighting type

Note any shadows on surfaces

General cleanliness of windows and luminaires

Presence of any obvious lighting deficiencies such as veiling reflections, glare, tunnel effect, flicker

Colour rendering

Question 15

How would you measure the daylight factor?

Answer 15

Use an illuminance meter

Measure illuminance outside

Measure illuminance inside at distances from windows

Divide internal illuminance by external readings then multiply by 100-DF

If electric lighting not used in daytime.DF > 5%

If electric light used in daytime then DF > 2%

Question 16

What are some general considerations for lighting surveys?

Answer 16

Best undertaken at night to test artificial light provision only

Let luminaires stabilise before measuring

Illuminance is normally taken at various workstations

Average illuminance uses measurements across the room using a grid pattern.

Question 17

What are considerations when taking readings?

Answer 17

Type of work being undertaken at point of measurement

Exact point where visual acuity will be focused

How much light is required for the task

Size of area and number of readings required

Any hazards in test area