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This NIOSH Toolbox Training program contains 52 different modules designed to stimulate safety discussions among your employees. Each module is intended to be completed in roughly 10 or 15 minutes, so a Toolbox Training session can be conducted once a week for the entire year. Each session counts toward your employee’s 8-hour annual MSHA refresher training, thus saving an entire day of work.. The modules are used to refresh employees on the procedures, policies, and practices of working safely at a specific mine site and can easily be tailored to fit conditions and situations found on your property. Every module follows the same format, so that as the weeks pass, miners will start to approach every safety situation in the same way. A typical Toolbox Training session contains five basic steps that cover all the information in the module. 1. Identification of the hazard and discussions about the types of injuries typically associated with the hazard. 2. Discussions of some of the causes of the hazard. The MSHA example included with each module should be referenced. 3. After the hazard and accident has been explained and understood, discussions about best practices and tips for avoiding a similar accident. 4. Review of similar conditions or near misses from your mine site using the leading questions on the form to start a discussion. Specific examples of equipment or structures on the site that could lead to the same accident should be discussed. The blank space on the module is used to add your own remarks and questions to supplement the given information. 5. Miners fill out the training record on the back of the form with name, initials, and date of training session. The modules are designed to be kept in a standard three-ring binder and easily photocopied. This way, the same set of modules can be used for years to come. A blank form is included that can be used to create more Toolbox Training modules. The key component of Toolbox Training is to start a discussion among employees that will allow them to see the hazards around them every day and respond to these hazards in a safe and consistent manner. To start a discussion, ask questions that need more than a one-word response. Get the miners to talk about similar situations from their own experiences and give suggestions about how to fix the hazards around them. Toolbox Training is a quick and effective way to cover specific mining hazards, but it only works if miners are involved in the discussion.

Jan 1, 2004

By J. W. Hunter, J. H. Jacobs

"Approximately 355 tons of nodules from Chamberlain; S. D., ore were processed in the 1-ton-per-day electrolytic-manganese pilot plant of the Bureau of lanes at Boulder City, Nev., in a continuous 3-month operation. The ore, ground to minus 48-mesh, was found to be amenable to leaching with acid directly or after roasting under reducing conditions in a Skinner muffled multiple-hearth furnace.Unroasted ore gave an acid-leach extraction of 84 to 88 percent of the manganese, which after neutralization showed an over-all extraction of between 81 and 85 percent of the manganese. The amount of iron extracted varied, but it was always,enough to permit the use of ammonia for neutralization.Roasted ore showed an acid-leach extraction of 89 to 91 percent of the manganese. A large amount of iron went-into solution, so that it was not economical to neutralize it entirely with ammonia. By neutralizing with calcine to a pH of 5.0 and completing -neutralization with ammonia to a pH of a.5 an over-all manganese extraction of 84 to 86 percent was obtained. The slight increase in. extraction on roasted ore probably would not justify the cost of roasting.Acid consumption averaged 1.75 pounds per pound of manganese extracted. Settling rates of the residue in leach solution were to slow to permit clarification in thickeners, but a Moore vacuum leaf filter proved to be satisfactory. Purification of raw leach solution was .accomplished readily by hydrogen sulfide with a low gas consumption. Electrolysis was normal, without difficulty, and with -current efficiency ranging between 62 and 66 percent.The use of Chamberlain modules for the production of electrolytic manganese would result in an operating cost of 0.8316 cent per pound higher than the cost of producing electrolytic manganese from Three Wids ore."

Mar 1, 1946

By Verne E. Hooker

The Bureau of Mines conducted a preliminary investigation to determine the state of stress in crystalline rock outcrops near Atlanta, Ga. The secondary principal stresses in a horizontal plane near the surface are compressive and are 500 to 3,000 psi. The maximum compressive stress is northeast-southwest in the Stone Mountain-Lithonia district but changes to northwest-southeast near Douglasville. The elastic constants were determined from data obtained by static and dynamic laboratory methods and in situ velocity measurements. Results show Young's modulus to be dependent upon both stress level and anisotropy in the rock. Average secant moduli obtained from triaxial tests were used to compute the applied stress from borehole deformation measurements.

Jan 1, 1966

By D. P. Schlick

As of June 30, 1970, Federal regulations required the operator of each underground coal mine to maintain the average concentration of respirable dust below legislative standards. As of March 1, 1971, over 152,000 respirable dust samples have been processed by the Bureau of Mines. Approximately 75 percent of underground working sections are being sampled in accordance with Federal regulations. Results indicate that 72 percent of the sections which have completed at least one basic sampling cycle are below 3.0 mg/m3, the standard in effect under the Federal Coal Mine Health and Safety Act of 1969 (P.L. 91-173). Notices of Violation were issued on 1,670 underground mines for failure to begin a sampling program; Withdrawal Orders were issued in 64 of these instances. Notices of Violation were issued on 1,121 sections where applicable dust levels were exceeded; Withdrawal Orders were issued in seven of these instances. There are 381 mining sections currently operating on permit; from the interim Compliance Panel.

Jan 1, 1971

By E. Chin

Bangladesh, whose population probably passed 100 million by yearend, remained one of the poorest countries in the world, with a per capita gross domestic product (GDP) of $126.2 Its only economically significant mineral production was natural gas. A few other minerals or mineral-based commodities were also produced, generally for local consumption. These included cement, clays, nitrogenous fertilizers, limestone, salt, steel, and pilot plant production of ilmenite and rutile. Exploration for oil was a continuing quest, which was hindered by a lack of funding and a hesitancy on the part of foreign petroleum companies to make long-term or expensive exploration commitments. PODUCTION AND TRADE Production of natural gas continued to increase as more use was being made of the abundant gas reserves variously put at between 7 and 16 trillion cubic feet. The main consumers were nitrogenous fertilizer producers and electric powerplants, but other industries were converting to natural gas from imported coal or fuel oil wherever possible.

Jan 1, 1986

By D. R. Torgoson, Th. G. Sahama

"This paper contains some new thermodynamic data for silicates in the series Mg2SiO4-Fe2siO4 and MgSiO3-FeSiO3 and gives the results of a thermodynamic attack on the problems of stability end parageneses.. Although some data are lacking satisfactory agreement with mineralogical and petrological observations is indicated.The use of thermodynamic methods in mineralogy and petrology has been rather limited, because accurate thermal data, especially for the more complicated and more important rock-forming minerals, have been too scanty to permit any systematic application to problems in those fields. It is, nevertheless, a fascinating task to investigate to what extent the mode of occurrence and the stability relations of the minerals and mineral parageneses, as revealed by petrological and mineralogical observations, agree with predictions of thermodynamics. At the present stage of development calorimetric data are needed for most of the abundant silicate minerals.Measurement of the heats of solution in hydrofluoric acid of minerals in the series Mg2SiO4-Fe2SiO4 and MgSiO3-FeSiO3 affords a ready means of obtaining their heats of formation from the oxides. Combination of such data with entropy and heat-capacity values gives a means of obtaining free energies of formation from the oxides, which, in turn, are connected di¬rectly with stability and paragenoses.The two silicates of magnesium, Mg2SiO4 and MgSi03, occur as rock-forming constituents as forsterite and clinoenstatite or enstatite. The orthosilicate (forsterite) forms a series of isomorphic mixtures with ferrous-orthosilicate (fayalite). The continuity of this series, suggested by petrological observations, has boon proved experimentally by Bowon and Shairer.4/ The present work shows that those minerals constitute a series of perfect solid solutions - that is, a series of solid solutions for which heats of formation from the individual pure silicates, Mg2Si04 and Fe2SiO4, aro negligibly small.The metasilicates of magnesium and iron also form an isomorphic series. However, this series differs from the forstorito-fayalite series in the fact that the most iron-rich mixtures, between about En10Fs90 and pure Fs, appear to be unstable with respect to the paragenesis iron-rich olivine plus quartz. The supposed instability of pure FeSiO3 as a crystalline compound, at least at high and at moderate temperatures, is remarkable, as no crystal struc¬tural reason for such instability is apparent. The present work indicates, also, that these minerals form a perfect series of solid solutions and throws additional light on the instability question.In the following, the samples used in this investigation will be described. For each of the natural olivines and orthopyroxenes, with the exception of sample L, a chemical analysis was made of the purified and actually used fraction. All the analytical work was carried cut by Oleg v. Knorring, and the specific gravity determinations, by moans of a pycnomctcr, by Oiva Joensuu, both of the University of Helsinki, Finland. The determinations of the optical properties were made by Mrs. Toini Mikkola, of the Geological Survey of Finland."

Feb 1, 1949

By Theodore R. Jolley

The estimated recoverable reserves in the area in the vicinity of Eska 2 mine are, 699,300 tons in the Chapin and Emery bas of the Maitland group. Those recoverable reserves are in the area between the Eska fault zone and Jonesville fault and extend down dip from the outcrops. No reserves were developed by the Eska 2 entry or by drill hole 14-16 in the Eska fault zone. The small quantity of reserves in the vicinity of the Eska 2 mine is insufficient to justify development of a now, modern .nine in this area. The estimated recoverable reserves in the area east of aka Creek are 974,500 tons in the Eska, Shaw, and Martin beds of the Eska group. Most of those reserves occur in the south limb of the syncline. It will be necessary to practice subjacent mining methods to recover these reserves in the Eska group. The Eska bed developed by the diamond drilling in this area comprises coal end few thin partings. The Shaw and Martin beds comprise two bunches of coal separated by partings, and the product from full-bed mining will require thorough preparation.

Jan 1, 1952

By F. S. Crawford

"After many years of safety activity in the United States in one form or another it becomes increasingly evident to those in contact with safety work that to achieve continuous good results in accident prevention there must be an aggressive organization behind the safety movement at each mine with fairly definite plan and policy. A study of the methods used by various companies and the results they have attained will be of value to the common cause of safety promotion.A study has been made of the safety records of the Menominee iron range in the Lake Superior district, and of data from the county mine inspector's report. Several companies on this iron range that have attained a certain measure of success in their work of accident prevention have given data, and a summary of their safety methods is presented.The Menominee iron range of Michigan lies in the southern portion of the upper peninsula of Michigan, bordering on Wisconsin. It consists of two main. divisions--the West Menominee Range, situated in Iron County in the vicinity of Iron River and Crystal Palls, and the East Menominee range situated in Dickinson County in the neighborhood or iron Mountain, Mich. The mines about Iron River and Crystal Falls are peculiarly subject to fires in a carbonaceous, sulphur-bearing black slate which appears in the footwall. This gives considerable trouble because fires in this material start from spontaneous heating. The methods of mining are top slicing and open stoping, working on benches along the sides of the stopes. The character of the ground varies from medium Soft ore to relatively hard ore which permits open stoping. Approximately one-third of the operating mines are equipped with a fan for main mechanical ventilation. The remainder are ventilated by natural draft. The East Menominee range is the older, top slicing having been used there for a number of years, and the timber mats have boon well developed. In common with all districts, some companies pay more attention to safety than others, although, those which do riot have the best records do pay some attention to safety.During the past three years the annual production per man employed has remained about constant, but in many mines a general decrease is shown in the accident record. The variation in the results attained can be ascribed mainly to the earnestness with which accident-prevention work is pursued, essentially regardless of the method of mining used. This is shown to be generally true, because the record indicates a steady decrease in one mine with an active safety department, while in adjoining mines with the same kind of ground and method of mining but where not such intensive attention has been paid to safety work, the accident record is high."

Oct 1, 1931

By H. H. Storch

"INTRODUCTION The first paper of this series contained data concerning the behavior of polyhalite (K2S04.MgS04.2CaS04.2H20) upon calcination and subsequent leaching with water at 100° C. It was found that upon heating polyhalite to temperatures between 298 and 500° C. the water of crystallization is driven off, leaving, an amorphous mixture of K2S04, MgS04, and CaS04. Two transition points were located; one at 298° C. which coincides with the vigorous evolution of steam; and one at 551° C. which results in the formation of a hard mass of crystals. The latter probably consist of a solid solution If the compounds langbeinite (K2504, 2MgS04), potassium dicalcium sulphate (K2304. 2CaS04), and anhydrite (CaS04). The heat of decomposition of polyhalite at 298° C. was measured and found to be 66,000 ± 5,000 calories per mol. The optimum temperature of calcination with regard to subsequent extrac¬tion with two parts of water (at "" 0° C.) is 430 to 450° C. for 65 to 100 mesh material, if one half hour at the calcination temperature is allowed. The maximum concentration of K2S04 obtainable in the extraction of calcined polyhalite is 11.4 grams per 100 grams of water. This concentration of K2304 is considerably above the equilibrium value (3.6 g. per 100 L. of H20 at 83° C.) with respect to the solid phases polyhalite, potassium calcium pentasulphate, ¬and anhydrite. The figure 11.4 K. of K2804 per 100 g. of H20 is also somewhat than the equilibrium value (9,65 g. per 100 g, H20) with respect to the solid phases potassium calcium pentasulphate and syngenite."

Oct 1, 1930

By F. S. Wartman

The presence of magnetite, either dissolved or suspended as solid crystals, in slags from the copper reverberatory furnace is a frequently mentioned cause of an abnormally high copper content in those slags. The presence of this oxide in the slag is to be expected, since it is present in appreciable amounts in both converter slag and roaster calcine which comprise a considerable proportion of the furnace feed. Magnetite is also a product of some of the furnace reactions. These abnormal losses result in several ways. Magnetite is supposed to favor the formation and retention of copper ferrite, in the slag. Crystals of solid magnetite suspended in the slag are objectionable-because they make the slag less fluid and often entrap globules of matte. Frequently these crystals settle into a layer at the slab-matte interface which may have such mechanical strength as to create a false bottom and interfere with furnace operation by preventing separation of matte from slag. Magnetite may, by crystallizing on the furnace bottom, build the bottom to such a level that the furnace can no longer be operated.

Jan 1, 1928

By D. K. Steele

An 18-in-diam column water elutriator was designed, tested, and operated by the Bureau of Mines for recovering nonferrous mixed metals from automobile shredder rejects. The waver elutriator separated metals from nonmetals contained in shredded nonmagnetic rejects. The unit was constructed and integrated into a local automobile shredding operation. Nonmagnetic rejects from the automobile shredder were fed onto the surface of a column of rising water. Dense materials fell through the rising water and were collected as a sink product at the bottom of the column; medium-density materials were removed as an intermediate product in a water flow through a discharge port located between the overflow and sink; and light materials were immediately carried out in the overflowing water at the top of the column as a float product. Nearly 99 pct of the mixed metals were recovered from the nonmagnetic rejects as a 70-pct-metal concentrate. Other operating conditions yielded a 93.7-pct-pure-metal product resulting in a 93.1-pct metal recovery. Float rejects are combustibles, light plastics, foam rubber, and minimal amounts of coated and uncoated copper wire. The middling discharge contained mainly medium-density rubber, plastics, glass, rock, coated and uncoated copper wire, and frequently some thin-sheet stainless steel and wrought aluminum. Maximum metal recovery in the operating program was achieved using a water velocity of 52 fpm (650 gpm). Maximum purity was obtained with a velocity of 88 fpm (1,100 gpm). .Water was recycled through a 12,000-gal baffled clarifying tank. Entrainment water losses with the float and middling rejects averaged 50 gpt of reject feed. Records maintained by the shredder operator show a 34-pct increase in nonmagnetic metals recovery during a 1-yr operation of the water elutriator as compared to recoveries from a previously used air classification system.

Jan 1, 1983

By Walter Kawa

In connection with its research in producing synthetic liquid fuels from coal, the Federal Bureau of Mines studied reactions of iron and iron compounds with hydrogen and hydrogen sulfide in batch autoclaves. The Bureau hoped to gain indirect evidence regarding the chemical changes that iron catalysts undergo when they are used in the hydrogenation of coal. The information obtained may be helpful in identifying the active form or forms of iron catalysts. At 450° C., with hydrogen at hundreds of atmospheres and hydrogen sulfide at 1 or 2 atmospheres, the thermodynamically stable form of iron is ferrous sulfide in the case of the metal, magnetite, ferric oxide, ferrous sulfate, ferrous oxalate, or the chlorides of iron. However, complete conversion to ferrous sulfide was not achieved at temperatures of 400° to 500° C. for kinetic reasons. Extensive sulfiding of iron, magnetite, ferric oxide, and ferrous oxalate occurred below 400° C., and some conversion of ferrous sulfate to ferrous sulfide occurred at 400° C. In the hydrogenation of coal, ferrous sulfide is the form of iron likely to be available for heterogeneous catalysis when starting with the metal, oxide, sulfate, or oxalate.

Jan 1, 1960

By James A. Morgan

FIELD MEASUREMENTS OF NOISE WERE MADE ON THE PERIPHERY OF ENCLOSURES DESIGNED, MANUFACTURED AND INSTALLED BY INDUSTRIAL ACOUSTICS COMPANY, INC. ON THE SECONDARY TACONITE CRUSHER AT THE JACKSON COUNTY IRON COMPANY PLANT IN BLACK RIVER FALLS, WISCONSIN. NOISE REDUCTION ACHIEVED BY THE ENCLOSURES WAS SUFPICIENT TO PERMIT REDUCTION OF CRUSHER ROOM NOISE TO 90 DBA, PROVIDED THAT OTHER SOURCES ARE APPROPRIATELY TREATED AND ACOUSTICAL ABSORPTION IS PROVIDED IN THE CRUSHER ROOM. SECONDARY CRUSHER NOISE WAS REDUCED 10 TO 15 DBA BY THE ENCLOSURES.

Jan 1, 1980

By F. E. Cash

The Holmes Safety Association was organized and named in honor of the late Dr. Joseph A. Holmes, first director of the United States Bureau of Mines. The association is a national organization and operates through local, sectional, or State chapters in mining, petroleum, and allied industries. The National Council of the Holmes Safety Association consists of representatives of State councils and local chapters, with the Director of the Bureau of Mines as president.

Jan 1, 1929

By Howard D. Jacobs

A bulk sample of oxidized taconite taken from the western Mesabi Range was evaluated by the Bureau of Mines using the Bureau-developed selective flocculation-desliming-cationic (or anionic) flotation process. The raw ore sample containing 32.3 pct Fe was treated by both cationic and anionic flotation. Using the cationic system the concentrates averaged. 37.2 wt-pct of the feed and contained 62.8 pct Fe and 4.7 pet Si02 with an iron recovery of 72.3 pet. With the anionic system, concentrates averaged 37.7 wt-pet of the feed and contained 63.0 pct Fe and 5.3 pct 8i02 with an iron recovery of 73.5 pct. A comparison of reagent costs showed that the cationic process cost 144.1 cents per long ton of crude ore and the anionic process 178.7 cents per long ton of crude ore. Reclaimed water comprised 86 pct of the total water requirement for anionic flotation and 88 pct for cationic flotation. The ore used in this study was one of three samples representing about 3.25 billion tons of oxidized taconite containing from 32 to 36 pct feed iron. Previous study had indicated that selective flocculation-desliming-cationic flotation would produce concentrates from the other two samples of 61.7 pct Fe and 5.1 pct Si02 at 67-pct Fe recovery, and 63.5 pct Fe and 4.3 pet Si02 at 8S-pct Fe recovery. By developing a successful treatment for these ores, the Bureau has insured the availability of technology for processing an amount of raw iron ore which, by itself, would supply U.S iron needs for 50 to 75 years at expected consumption rates.

Jan 1, 1981

By Robert P. Vinson, Kissell. Fred N., Edward D. Thimons

"The Bureau of Mines investigated the presence and extent of methane accumulations in mine roof cavities using a full-scale mine model. Methane was released at a constant rate into the roof of a cavity built onto a 700-ft wind tunnel. Two box-shaped roof cavities were used in the study: one had a volume of 114.7 cu ft; and the other had a volume of 57.3 cu ft. Methane concentration was measured at 28 sampling points in the cavities using 21 different combinations of gas emission rates and air velocities. Brattice hung in the cavity helped reduce methane concentrations without auxiliary ventilation. It was also found that the effective ventilation rate increased by a factor of 40 in the large cavity and by a factor of 20 in the small cavity when air velocity was increased from 100 to 600 fpm.INTRODUCTIONAny location in a coal mine where 5 pct or more of methane is present constitutes a potential site for an explosion and roof cavities are likely locations. Unfortunately, little is known about the buildup of methane in roof cavities. Some research has been done using scale models where no air flows past the cavity so that methane disperses only by diffusion (5) 4 a rare situation in mines.No known cavity-model investigations have been made that simulate air and methane flow conditions normally encountered underground. These Bureau of Mines studies were undertaken to determine the extent and manner of methane buildups in coal mine roof cavities with air velocities in the range normally found in coal mines and with various methane emission rates."

Jan 1, 1978

By Robert P. Vinson

The Bureau of Mines investigated the presence and extent of methane accumulations in mine roof cavities using a full-scale mine model. Methane was released at a constant rate into the roof of a cavity built onto a 700-ft wind tunnel. Two box-shaped roof cavities were used in the study: one had a volume of 114.7 cu ft; and the other had a volume of 57.3 cu ft. Methane concentration was measured at 28 sampling points in the cavities using 21 different combinations of gas emission rates and air velocities. Brattice hung in the cavity helped reduce methane concentrations without auxiliary ventilation. It was also found that the effective ventilation rate increased by a factor of 40 in the large cavity and by a factor of 20 in the small cavity when air velocity was increased from 100 to 600 fpm.

Jan 1, 1978

By Avery H. Reed

[The Bureau of rides is making a general study of the occurrence of the Clinton red iron ores of Alabama. In the course of this study, it developed that the iron-ore seams of the Woodstock and Bucksville areas were virtually unexplored., and the nature and extent of the ore deposits were undetermined. As a part of the work of the project, the Bureau investigated the occurrence of red iron ore in the .areas. Eighty-four channel samples, representing 317.6 linear feet, were taken from l2 locations along the outcrop of the red iron-ore seams, Ten diamond-drill holes, amounting to 3915.5 linear feet, were drilled. In these areas, commercial- and marginal-grade ores of minable thickness have been shown. It is estimated that 4,500,000 tons of indicated ore and 6,700,000 tens of inferred commercial-grade ore averaging 5.1 feet thick, 47.6 percent Fe, 26.1 percent insoluble, 0.1 percent CaO, and 0.04 percent P; 7,200,000 tins of inferred marginal grade ore averaging 6.1 feet thick, 36.2 percent Fe, .35.0 percent insoluble, 3.9 percent CaO, and 0.14 percent P; and 18,500,000 tons of ferruginous sandstone averaging 12.2 feet thick, 19.2 percent re, 50.1 percent insoluble, 9.6 percent CaO, and 0.14 percent P are present in the areas.. All tonnages are estimated as gross tons of recoverable ore in place, based' on 65-percent mining recovery. In accordance with established policy of the Bureau of Mines of publishing factual data as soon as possible after completion of field work, this description of the Woodstock and Bucksville areas is presented. As soon as work is completed in other areas additional reports will be prepared.]

Jan 1, 1953

By N. P. Kripakov

The Bureau of Mines has developed a unique new mine design procedure to determine the changing static load distributions imposed on under-ground support structures during the mining cycle. The procedure reduces the complexities associated with analyzing a three-dimensional problem. A combination of the multiple-seam displacement-discontinuity model and a two-dimensional finite-element window model produces refined results for a specific area of interest by assuming displacement compat-ibility between models. Input to the procedure includes the geometry of mined-out areas in up to two adjacent seams, the rock mass characteris-tics of the surrounding geology, the in situ stress conditions, and the mining sequence. The displacement-discontinuity program calculates ex-pected loadings for mine structures affected by the mining cycle and/or by overlying or underlying seams. Pseudoelastic finite-element analysis using a yield-factor approach determines the stability of coal pillars by simulating the degree and extent of nrogressive rib failure and sub-sequent load transfer. Application of the procedure is demonstrated on a field problem. In-duced stress changes predicted from the numerical model analysis are in reasonably good agreement with stress measurements obtained from an instrumented chain pillar affected by remnant workings in an upper seam.

Jan 1, 1988

By Lloyd A. Morley, Alan M. Christman

PART A. ELECTRICAL EQUIPMENT – GENERAL Paragraph 1. Electrical Equipment; Examination. All electric equipment shall be examined, tested, and properly main¬tained by a qualified person to assure safe operating conditions. The examinations and tests shall be performed at intervals not exceeding six (6) months unless otherwise specified in Parts A, B, C, D, and E. When a potentially dangerous condition is found on electric equipment, such equipment shall be removed from service until such condition is corrected. A record of such examinations shall be kept and made available to an authorized representative of the Secretary and to the authorized repre¬sentative of the miners in such mine. Each item of major equipment, in¬cluding substations, switchgear, load centers, and so forth except powered hand tools, shall be recorded separately. The record of such examination shall include all dangerous conditions found, corrective action taken, and name of examiner, and shall be signed by the person responsible for main¬taining the equipment in safe operating condition, who shall also be a qualified person. Paragraph 2. Electrical Work; Qualified Personnel. No electrical work shall be performed on electrical distribution circuits or equipment, except by a qualified person or by a person trained to perform electrical work and to maintain electrical equipment under the direct supervision of a qualified person. Disconnecting devices shall be locked out and prominently tagged by the persons who perform such work, except that in cases where locking out is not possible, such devices shall be opened and prominently tagged by such persons. Locks and tags shall be removed only by the persons who installed them or, if such persons are

Jan 1, 1976