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.~ 4 57.12048 Maintenance of Electric Supply and Communication Lines" (also referred to as National Bureau of Standards Handbook 81, Nov. 1. 1961), and Supple- ment 2 thereof issued March 1968. which are hereby incorporated by ref- erence and made a part hereof. These publlcatlons and documents may be ob- tained from the Sucerin Cendent of Doc- uments, U.S. Government Prln't[ng Of- CSce, Washington. D.C. 20902. or may be examined 1^ any Metal and Nonmetal MSoe Safety and Health District or Subdistrict OCC1ce of the Mlne Safety and Health Adminiscracfon. 2048 Commuaieatinn COadUCLOI'8 0o power poles. Telegraph, telephone, or signal wires shall not be installed on the same crosearm with power contluc[ors. When carried on Doles supporting Dowerllnes. they shall be installed ae ececl fled by the Natfonal Electrical Code. 457.12050 Installation of trolley wires. Trolley woes shall be ins called ac ]east seven feet above rails where height perm[ts, and aligned and sup- ported to sal tably control sway and sag 457.12053 Circuits powered from trol- ley wires. Ground wires Cor I[ghcmg circuits powered from croUey wires shall be connected secure lY to the ground re- ~clrcult. SURFACE ONL]' 857.12085 Short circuit and Ilghtaing protection Powerllnee, including trolley wires, and telephone circuits shall be pro- tected against short clrcul is and ]Ight- ning. 457.12086 Guarding trolley wires and bare Powerllnee. Where metallic tools or equipment can come Sn contact with trolley wires or bare Dowerllnes, the ]Ines shall be guarded or deenerglzed. 457.12087 lnstellatlon of transformers. Transformers shall be totally en- closed, or shall be placed at least 8 feet above the ground, or Installed In a 30 CFR Ch. I (7-1-94 Ed transformer house, or surrounded substan clal fence at least 6 feet and at ]east 3 feet Crom any ens[ parts, casings. or wiring. 457.12068 Locking transformer i sores. Transformer enclosures shall be locked against unauthorized entry 457.12088 Lightning protectlori telephone wires end ungroi conductors. Each ungrounded conductor or phone wire that Leads undergroun is dSrectly exposed to lightning eh equlDced with suitable ]lghtning~ tors o[ approved type wlthln 1000 the Dolnt where the circuit enter mine. Llghtmng arrestors shall bi netted LO a low resistance grog medium on the surface and slu separated from neutral grounds distance of not less than 26 feet. 457.12071 Movement or operatl equipment near high•v powerlines. ' When equipment must be mov operated near energized high-vi powerllnes (ocher Chan trolley and the clearance fs lees than 1( the lines shall be deenerglzed or precautionary measures shall be t UNDERGROUND ONLY ..13 ;% 467.12090 Bare conductor guard Trolley wires and bare Dower of tors shall be guarded at mantrlp Ing and unloading Dalnte, and ~aE stations. Where ouch trolley wfri bare power conductore are less~t feet above the tall, they shall be'~ ed at al] points where persona ~1 peas regularly beneath. 457.12091 Bonding metal pl ~~ ground return circuits. ::rT All metal Dlcelines, 1,000 feet a 1n length running parallel tol~_ tracks, that are used ea a gro turn circuit shall be bonded to-~' turn circuit rail ac the ends of th"f ]1ne and ac lntervala not to exeb Ceec. ,s ~r a Safety and Heath Admin., Labor 12082 Isolation of powerllnes. lwerllaes shall be well separated or .]sled fkom waterlines, telephone sand afr ]Ines. 120&9 Support of power cables in shafts and boreholes. lover cables in shafts and boreholes .1 be fastened securely Sn each a leer u to prevent undue strain on sheath, lnsulatloa, or conductore. 12084 Branch circuit dlscomect- !sg devices. Isconnectiag switches that can be ¢ad safely under load shall be pro- id~underground at all branch cIr- e extending from primary Dower itite near shafts, adlta, levels and Iholee. ~li~-' 32()86 14ansformer stallons. h` raas[ormer stations shall be en- sd~to prevent persona from unln- ;lonally or Inadvertently contact- energized parts. ,12086 Location of trolley wire. rolleY and trolley feeder wire shall nstalled oDDOS1 to the clearance side tulageways. However, thin standard efa0t apply where physical llmlta- Is would prevent the safe lnstalla- I~Or use of such trolley and trolley !er`wire. ~c. 099 Splicing trolling cables. oAepllce, except a vulcanized epllce Ifs] equivalent, shall be made to a cable wlthln 25 feet of the ma- ~Ualees the machine 1s equlpced cable reel or other Dower teed kyayout-retrieval system. How- temDOrery epllce may be made the equipment for repair. rf L-Compressed Alr and Boilers General requirements for 'and pressure vesseb. ~llers and pressure vessels shall ri6tructed, laetalled, and main- ~k1a accordance with the stand- dececiflcatlona of the American Hof Mechanical Engineers Boller _ ore Vesae] Code. § 57.13015 467.15010 Reciprocating-type air com• preseors. (a) Reciprocatf ng-tyce air compres- sors rated over 10 horsepower shall be equlDced with automatic temperature- actuated shutoff mechanisms which shall be set or adlusted to the compres- sor whe^ the normal operating tem- perature is exceeded by more than 26 percent. (b) However, this standard does not apply to reciprocating-type afr com- pressors rated over ]0 horsepower iC equlpced with fusible Dluga that were installed In the compressor df echarge I1nea before November 15. 1979, and de- efgned to melt at temperatures at least 50 degrees below the flash point of the cornpreeaors' ]ubrfcating oil. 457.18011 Air receiver tanks. Alr receiver tanks shall be equl Aped with one or more au tomatlc pressure- rellef valves. The total relleving capac- ity of the relief valves shall prevent pressure from exceeding the maximum allowable working pressure 1n a re- ceiver tank by not more than 10 per- cent. Alr receiver tanks also shall be equipped with lndfcating pressure gages which accurately mane ore the pressure wlthln the air receiver tanks. 457.19012 Compressor air Intakes. Compressor air Intakes shall be In- stalled to ensure that only clean, uncontaminated afr enters the com- preseore. 457.19015 Inspection of compreaeed- alr receivers and other unrirod pressure vessels. (a) Compressed-afr receivers and other unfired pressure vessels shall be lnecected by Snecectore holding a valid National Board Commission and Sn ac- cordance with the applicable chapters of the Natfonal Hoard lnecectfon Code, a Manua] Cor Boller and Pressure Ves- sel Inecectore, 1979. Thla code 1s incor- porated by reference and made a part of this standard. It may be examined at any Meta] and Nonmetal Mfne Safety and Health District Otflce of the Mlne Safety and Health Adminietratfon, and may be obtained fYom the publisher, the Natfonal Boartl of Boller and Pres- sure Vessel lnsceccore, 1055 Crupper Avenue, Columbus. Ohio 93229.