15. (1) This section applies only to X-ray machines used for industrial radiography or industrial fluoroscopy but does not apply to an X-ray machine to which section 17 applies. (2) No X-ray machine to which this section applies shall be used except by or under the supervision of a competent person. (3) In addition to any other requirements of this Regulation, the following requirements apply with respect to every X-ray machine to which this section applies: 1.  The control panel of the X-ray machine shall have a plainly visible warning light to indicate when X-rays are being produced in the X-ray tube. 2.  The X-ray machine, if installed in a permanent location or if designed for portable or mobile operation but used regularly in one location, shall be contained in an enclosure. 3.  No person shall be permitted in the enclosure required by paragraph 2 while X-rays are being produced. 4.  The enclosure required by paragraph 2 shall be provided with, i.  reliable locks or interlocks to prevent any person from entering a radiation enclosure during an exposure and, where an exposure is terminated by an interlock, it shall only be possible to restart the exposure from the control panel, and ii.  conspicuous warning lights of failsafe or redundant design near each entrance to the enclosure that indicate when X-rays are being produced, and paragraph 3 of section 11 does not apply. 5.  If the enclosure required by paragraph 2 is of such a size or is so arranged that the operator cannot readily determine whether it is unoccupied, it shall be provided with, i.  suitable audible or visible pre-exposure warning signals within the enclosure that shall be actuated for not less than ten or more than thirty seconds immediately before the initiation of an X-ray exposure, ii.  suitable audible or visible warning signals within the enclosure that shall be actuated during the X-ray exposure, and iii.  a suitable exit to enable any person to leave the enclosure without delay and without having to pass through the primary X-ray beam or an effective means, within the enclosure, that, A.  prevents or interrupts an X-ray exposure, B.  cannot be reset from outside the enclosure, and C.  can be reached without having to pass through the primary X-ray beam. 6.  An X-ray machine shall be operated, and, where an enclosure is required by paragraph 2, the enclosure shall be shielded in such a manner that, i.  an X-ray worker is not likely to receive an effective dose equivalent in excess of 1 millisievert per week, and ii.  a worker who is not an X-ray worker is not likely to receive an effective dose equivalent in excess of 100 microsieverts per week. 7.  The employer shall ensure that a direct reading dosimeter of a suitable type is provided to each X-ray worker who in the course of his or her work may be exposed to an air kerma rate in excess of 100 micrograys per hour. 8.  An X-ray worker provided with a direct reading dosimeter shall use it and shall determine the amount by which its reading has increased during each work day and record that amount at the end of the work day. 9.  The employer shall retain the direct reading dosimeter records of each X-ray worker provided with such a dosimeter for a period of at least three years. 10.  At least one radiation survey meter of a suitable type shall be provided for each portable or mobile X-ray machine and it shall be calibrated at least once every twelve months and kept in good working order.