The Traffic Signs Regulations and General Directions 2016

5.—(1) The light signals may only be placed if they are placed so that they face the stream of traffic to which they are intended to convey the warnings, information, requirements, restrictions or prohibitions prescribed.

(2) A container enclosing the lamps of the light signals must be coloured black except that—

(a) if a container encloses lamps of the light signals provided for at item 23, 25, 32, 33 or 34 it may be coloured grey instead of black;

(b) the back of a container enclosing the light signals provided for at item 11 to 14, 16 to 18 or 20 to 22 may be coloured yellow; and

(c) the container may have a white border not less than 45 nor more than 55 mm wide.

(3) The light signals other than the signals provided for at item 5 may be mounted on a backing board, which must be coloured black and may have a white border not less than 45 nor more than 55 mm wide.

(4) In the case of the light signals provided for at item 5, the back of the backing board may be coloured black or grey.

(5) Where the light signals are mounted on a post specially provided for the purpose, that part of the post which extends above ground level must either be coloured grey, black, brown, dark green or dark blue or be in a non-reflective metallic finish.

(6) Despite sub-paragraph (5)—

(a) the post may be marked with a yellow or white band not less than 140 nor more than 160 mm deep and the lower edge of the band being not less than 1500 nor more than 1700 mm above ground level; and

(b) where the light signals provided for at item 1, 3, 4, 9 to 11 or 13 to 22 are installed temporarily, the containers in which the posts are placed may be coloured with alternate red and white horizontal stripes.

(7) The portable light signals provided for at item 2 and the signals provided for at items 9 to 13 when used at a portable crossing, instead of being mounted on a post coloured in accordance with sub-paragraph (5), may be mounted on a post coloured yellow (but having no yellow or white band as specified in sub-paragraph (6)) or on a tripod or other support coloured yellow.