# The Traffic Signs Regulations and General Directions 2016, Paragraph 5

Extent: E+W+S

In relation to each aspect of performance specified in column (2) of an item in the Table below, the warning light must comply the requirement or test specification of British Standard BS EN 12352:2006 specified in column (3).
(1)
Item
(2)
Aspect of performance
(3)
Requirement or test specification and class
1
Area, angle and luminous intensity
Class L1 or L3 in Table 1
2
Light emitting surface
For class L1 lights: paragraph 4.1.2.1
For class L3 lights: class P1
3
Colorimetric performance of light emitted
Class C yellow 1 in Table 2
4
Retro-reflective device
Class R2
5
Automatic photosensitive switching
Class A1
6
Continuity of emitted light
Class F1 (steady) or class F2 (but see NOTE)
7
On-time (flashing lights)
Class O2
8
Mechanical strength
Class M4
NOTE: A light flashing at a rate of 900 flashes per minute or more is deemed to comply with class F1.

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Source: https://www.legislation.gov.uk/uksi/2016/362/schedule/13/part/11/paragraph/5 (the official version)
Page: https://openlegislation.uk/traffic-signs-regulations-and-general-directions-2016/schedule-13/part-11/paragraph-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.