# The Coal Mines (Cardox and Hydrox) Regulations 1956, Regulation 23


(1) Any person about to fire a shell shall determine the danger zone likely to be created.
(2) No person shall fire a shell unless he has—
(a) at each entrance to that danger zone either posted a sentry or placed an appropriate fence conspicuously marked with the words “danger” and “shot firing”;
(b) ensured that all persons have withdrawn from that zone or have taken proper shelter; and
(c) himself taken proper shelter.

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Source: https://www.legislation.gov.uk/uksi/1956/1942/regulation/23 (the official version)
Page: https://openlegislation.uk/coal-mines-cardox-and-hydrox-regulations-1956/regulation-23
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.