{"data":{"id":"us/30-cfr-18.2","jurisdiction":"us","citation":"30 CFR 18.2","heading":"Definitions.","body":"As used in this part—\nAcceptance means written notification by MSHA that a hose has met the applicable requirements of this part and will be listed by MSHA as acceptable flame-resistant auxiliary equipment.\nAcceptance marking means an identifying marking indicating that the hose has been accepted by MSHA for listing as flame resistant.\nAccessory means associated electrical equipment, such as a distribution or splice box, that is not an integral part of an approved (permissible) machine.\nAfterburning means the combustion of a flammable mixture that is drawn into a machine compartment after an internal explosion in the compartment.\nApplicant means an individual, partnership, company, corporation, organization, or association that designs, manufactures, assembles, or controls the assembly of an electrical machine or accessory and seeks approval, certification, or permit, or MSHA acceptance for listing of flame-resistant hose.\nApproval means a formal document issued by MSHA which states that a completely assembled electrical machine or accessory has met the applicable requirements of this part and which authorizes the attachment of an approval plate so indicating.\nApproval plate means a metal plate, the design of which meets MSHA's requirements, for attachment to an approved machine or accessory, identifying it as permissible for use in gassy mines or tunnels.\nAssistant Secretary means the Assistant Secretary of Labor for Mine Safety and Health.\nBranch circuit means an electrical circuit connected to the main circuit, the conductors of which are of smaller size than the main circuit.\nBureau means the U.S. Bureau of Mines.\nCertification means a formal written notification, issued by MSHA, which states that an electrical component complies with the applicable requirements of this part and, therefore, is suitable for incorporation in approved (permissible) equipment.\nCertification label means a plate, label, or marking, the design of which meets MSHA's requirements, for attachment to a certified component identifying the component as having met the MSHA's requirements for incorporation in a machine to be submitted for approval.\nComponent means an integral part of an electrical machine or accessory that is essential to the functioning of the machine or accessory.\nConnection box (also known as conduit or terminal box) means an enclosure mounted on an electrical machine or accessory to facilitate wiring, without the use of external splices. (Such boxes may have a joint common with an explosion-proof enclosure provided the adjoining surfaces conform to the requirements of subpart B of this part.)\nCylindrical joint means a joint comprised of two contiguous, concentric, cylindrical surfaces.\nDistribution box means an enclosure through which one or more portable cables may be connected to a source of electrical energy, and which contains a short-circuit protective device for each outgoing cable.\nExperimental equipment means any electrical machine or accessory that an applicant or MSHA may desire to operate experimentally for a limited time in a gassy mine or tunnel. (For example, this might include a machine constructed at a mine, an imported machine, or a machine or device designed and developed by MSHA.)\nExplosion-proof enclosure means an enclosure that complies with the applicable design requirements in subpart B of this part and is so constructed that it will withstand internal explosions of methane-air mixtures: (1) Without damage to or excessive distortion of its walls or cover(s), and (2) without ignition of surrounding methane-air mixtures or discharge of flame from inside to outside the enclosure.\nFlame-arresting path means two or more adjoining or adjacent surfaces between which the escape of flame is prevented.\nFlame resistant as applied to cable, hose, and insulating materials means material that will burn when held in a flame but will cease burning when the flame is removed.\nFlammable mixture means a mixture of methane or natural gas and air that when ignited will propagate flame. Natural gas containing a high percentage of methane is a satisfactory substitute for pure methane in most tests.\nGassy mine means a coal mine classed as “gassy” by MESA or by the State in which the mine is situated.\nIncendive arc or spark means an arc or spark releasing enough electrical or thermal energy to ignite a flammable mixture of the most easily ignitable composition.\nIntrinsically safe means incapable of releasing enough electrical or thermal energy under normal or abnormal conditions to cause ignition of a flammable mixture of methane or natural gas and air of the most easily ignitable composition.\nMESA means the United States Department of the Interior, Mining Enforcement and Safety Administration. Predecessor organization to MSHA, prior to March 9, 1978.\nMobile equipment means equipment that is self-propelled.\nMSHA means the United States Department of Labor, Mine Safety and Health Administration.\nNormal operation means the regular performance of those functions for which a machine or accessory was designed.\nPermissible equipment means a completely assembled electrical machine or accessory for which an approval has been issued.\nPermit means a formal document, signed by the Assistant Secretary, authorizing the operation of specific experimental equipment in a gassy mine or tunnel under prescribed conditions.\nPlane joint means two adjoining surfaces in parallel planes.\nPortable cable, or trailing cable means a flame-resistant, flexible cable or cord through which electrical energy is transmitted to a permissible machine or accessory. (A portable cable is that portion of the power-supply system between the last short-circuit protective device, acceptable to MSHA, in the system and the machine or accessory to which it transmits electrical energy.)\nPortable equipment means equipment that may be moved frequently and is constructed or mounted to facilitate such movement.\nPotted component means a component that is entirely embedded in a solidified insulating material within an enclosure.\nPressure piling means the development of abnormal pressure as a result of accelerated rate of burning of a gas-air mixture. (Frequently caused by restricted configurations within enclosures.)\nQualified representative means a person authorized by MSHA to determine whether the applicable requirements of this part have been complied with in the original manufacture, rebuilding, or repairing of equipment for which approval, certification, or a permit is sought.\nSplice box means a portable enclosure in which electrical conductors may be joined.\nStep (rabbet) joint means a joint comprised of two adjoining surfaces with a change(s) in direction between its inner and outer edges. (A step joint may be composed of a cylindrical portion and a plane portion or of two or more plane portions.)\nThreaded joint means a joint consisting of a male- and a female-threaded member, both of which are of the same type and gage.\nVoluntary consensus standard means a safety standard that:\n(1) Is developed or adopted by a voluntary consensus standards body; and\n(2) Prescribes safety requirements applicable to equipment for which applicants are seeking approval, certification, extension, or acceptance under this part.\nVoluntary consensus standards body means a domestic or international organization that plans, develops, establishes, or coordinates voluntary consensus standards using agreed-upon procedures that are consistent with the National Technology Transfer and Advancement Act of 1995 (15 U.S.C. 3710) and the Office of Management and Budget's Circular A-119 (Jan. 27, 2016).","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 A—General Provisions"],"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":"f5b247ed683a8f41c65491b0066feeda32763fa6093002406b3a08e72b8d00d9","source_id":"us-cfr","stale":true,"prev":"us/30-cfr-18.1","next":"us/30-cfr-18.3"},"notice":"GroundRules: Original legal text. Not legal advice."}