{"data":{"id":"us/30-cfr-18.50","jurisdiction":"us","citation":"30 CFR 18.50","heading":"Protection against external arcs and sparks.","body":"Provision shall be made for maintaining the frames of all off-track machines and the enclosures of related detached components at safe voltages by using one or a combination of the following:\n(a) A separate conductor(s) in the portable cable in addition to the power conductors by which the machine frame can be connected to an acceptable grounding medium, and a separate conductor in all cables connecting related components not on a common chassis. The cross-sectional area of the additional conductor(s) shall not be less than 50 percent of that of one power conductor unless a ground-fault tripping relay is used, in which case the minimum size may be No. 8 (AWG). Cables smaller than No. 6 (AWG) shall have an additional conductor(s) of the same size as one power conductor.\n(b) A means of actuating a circuit-interrupting device, preferably at the outby end of the portable cable.\nNote:\nThe frame to ground potential shall not exceed 40 volts.\n(c) A device(s) such as a diode(s) of adequate peak inverse voltage rating and current-carrying capacity to conduct possible fault current through the grounded power conductor. Diode installations shall include: (1) An overcurrent device in series with the diode, the contacts of which are in the machine's control circuit; and (2) a blocking diode in the control circuit to prevent operation of the machine with the polarity reversed.","path":["Title 30—Mineral Resources","CHAPTER I—MINE SAFETY AND HEALTH ADMINISTRATION, DEPARTMENT OF LABOR","SUBCHAPTER B—TESTING, EVALUATION, AND APPROVAL OF MINING PRODUCTS","PART 18—ELECTRIC MOTOR-DRIVEN MINE EQUIPMENT AND ACCESSORIES","Subpart B—Construction and Design Requirements"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-30.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:25:24Z","sha256":"929c83c20d7ef93cdb84dcf5b48c61587c59f27669230cb185ccdd5ac6312e81","source_id":"us-cfr","stale":true,"prev":"us/30-cfr-18.49","next":"us/30-cfr-18.51"},"notice":"GroundRules: Original legal text. Not legal advice."}