Illumination of signs shown in diagrams 560 and 561
21.—(1) The signs shown in diagrams 560 and 561 shall not be illuminated by the fitting of a means of internal or external lighting.
(2) A sign shown in a diagram whose number appears in column (2) of an item in the Table and having the dimension specified in column (3) of that item shall be illuminated by either of the methods prescribed by paragraph (3) which are shown in column (4) of the item, and by no other method.
Table
| (1) | (2) | (3) | (4) |
|---|---|---|---|
| Item | Diagram | Dimension | Method of illumination |
| 1. | 560 | 150 millimetres diameter | Paragraph 3(a) or (b) |
| 2. | 560 | 75 millimetres or more but less than 150 millimetres diameter | Paragraph 3(c) or (d) |
| 3. | 561 | 180 square centimetres area | Paragraph 3(b) or (e) |
| 4. | 561 | not less than 45 square centimetres but not more than 180 square centimetres area | Paragraph 3(d) or (e) |
(3) The prescribed methods of illumination are—
(a)the use of 14 circular reflectors of the corner cube type, each reflector having a diameter of 22 millimetres;
(b)the use of retroreflecting material extending over the whole surface of the sign;
(c)the use of a single circular reflector of the corner cube type extending over the whole surface of the sign;
(d)the use of reflectors consisting of bi-convex lenses extending over the whole surface of the sign; and
(e)the use of a single rectangular reflector of the corner cube type extending over the whole surface of the sign.