Change to BS5489:2013 (which replaces BS5489:20003)
In 2013 the British standard was updated to recognise the use of the S/P ratio of a light source to determine the actual visible lighting level.
The ratio of the luminous output of a light source evaluated according to the CIE scotopic spectral luminous efficiency function, V'(λ), to the luminous output evaluated according to the CIE photopic spectral luminous efficiency function, V(λ)
Table A.7 – Variation of lighting level with S/P ratio of light source
| Lighting class | (e.g. Ra <60 Or when s/p ratio of light source is not known or specified) | S/P ratio = 1.2 and Ra ≥60 (e.g. some types of warm white lamp such as metal halide) | S/P ratio = 2 and Ra ≥60 (e.g. Some types of cool white compact fluorescent or LED) | |||
| Eav | Emin | Eav | Emin | Eav | Emin | |
| P1 | 15 | 3 | 13.4 | 2.7 | 12.3 | 2.5 |
| P2 | 10 | 2 | 8.6 | 1.7 | 7.7 | 1.5 |
| P3 | 7.5 | 1.5 | 6.3 | 1.3 | 5.5 | 1.1 |
| P4 | 5 | 1 | 4 | 0.8 | 3.4 | 0.7 |
| P5 | 3 | 0.6 | 2.2 | 0.4 | 1.8 | 0.4 |
| P6 | 2 | 0.4 | 1.4 | 0.4 | 1.1 | 0.4 |
Table A.5 – Lighting classes for subsidiary roads with low speed traffic
(v ≤ 30 mph) – Mixed traffic without parked cars present
| Traffic Flow | Lighting class | |||
| Ambient luminance: very low (E1) | Ambient luminance: low (E2) | Ambient luminance: moderate (E3) | Ambient luminance: high (E4) | |
| Busy | P3 | P3 | P2 | P2 |
| Normal | P4 | P3 | P3 | P2 |
| Quiet | P4 | P4 | P3 | P3 |
NOTE 1 Low speed traffic equates to 20 mph or 30 mph.
NOTE 2 Table A.5 assumes no parked cars – see risk assessment in A.3.3.2.
NOTE 3 If facial recognition is important then an SC lighting class from BS EN 13201-2:2003 can be selected as an additional criterion.
Good colour rendering contributes to better facial recognition.
NOTE 4 To provide for uniformity, the actual value of the maintained average illuminance is not to exceed 1.5 times the value indicated for the class.
NOTE 5 It is recommended that the actual overall uniformity of illuminance Uo be as high as reasonably practicable.
NOTE 6 Grey highlighting indicates situations that would not usually occur in the UK.
NOTE 7 The ambient luminance descriptions E1 to E4 refer to the environmental zone as defined in the ILP guidance notes [N4].
| Environmental zone | Mounting height | Cleaning frequency | |||||
| 12 months | 24 months | 36 months | 48 months | 60 months | 72 months | ||
| E1/E2 | ≤6 m | 0.96 | 0.96 | 0.95 | 0.94 | 0.93 | 0.92 |
| E1/E2 | >6 m | 0.96 | 0.96 | 0.95 | 0.94 | 0.93 | 0.92 |
| E3/E4 | ≤6 m | 0.94 | 0.92 | 0.9 | 0.88 | 0.86 | 0.84 |
| E3/E4 | >6 m | 0.96 | 0.96 | 0.95 | 0.94 | 0.93 | 0.92 |
Source: The Institution of Lighting Professionals (ILP) www.theilp.org.uk/resources/