5.—(1) The person in control of a site shall ensure that there is not present at any one time a total quantity of 25 tonnes or more of dangerous substances at the site unless safety signs are displayed at such places as will give adequate warning to firemen before entering the site in an emergency that dangerous substances are present.
(2) The safety signs referred to in paragraph (1) shall be warning signs as defined by clause 3.6 of Part I of BS 5378 bearing the hazard warning symbol (but not the text) shown in the last entry of column 2 of Schedule 3 to these Regulations; and all such signs shall comply with that Part with respect to colours and layout.