Governs work on, or close enough to face the hazards of, exposed live parts. Only qualified employees may handle or work on exposed energized lines or parts, or enter areas holding unguarded, uninsulated energized parts at 50 volts or more. Lines and equipment are treated as energized unless deenergized under 1926.961. At least two employees must be present when installing, removing or repairing lines above 600 volts, deenergized lines where contact with other parts above 600 volts is possible, or transformers, capacitors, regulators and similar equipment where parts above 600 volts can be contacted; when mechanical equipment (insulated aerial lifts excepted) works near such parts; and for other work of equal or greater electrical hazard. Exceptions: routine switching shown safe, live-line tool work with no reach or contact exposure, and emergency repairs needed to safeguard the public. Minimum approach distances (MAD): the employer must establish distances no smaller than those computed with the Table V-2 equations for ac or Table V-7 for dc, and must apply the technical criteria and method set out in Appendix B (mandatory for this purpose), which explains the electrical component (air insulation for the maximum transient overvoltage; from 72.6 to 800 kV it is computed as D = 0.3048(C + a) x VL-G x T, with C of 0.01 or 0.011 depending on what spans the gap, a from the Table 3 saturation equations, and phase-to-phase T derived as 1.35 times the phase-to-ground value plus 0.45), the ergonomic adder for inadvertent movement, altitude correction above 900 m (3,000 ft) using Table V-4, and optional reduction by controlling overvoltage (blocking reclosing, surge arresters, portable protective gaps, switching restrictions). Alternative Tables V-5 and V-6 apply at 900 m or lower. Above 72.5 kV, no later than April 1, 2015, the employer sets the highest expected phase-to-ground transient overvoltage (per unit) by engineering analysis or assumes the Table V-8 value; unless Table V-8 values are used, persons competent in transmission and distribution system design must make the determination. Portable protective gaps require five standard deviations between gap statistical sparkover and the statistical withstand voltage, and any engineering analysis must be available to employees and OSHA for examination and copying. No employee may approach, or bring a conductive object, inside the MAD unless insulated from the part (rubber gloves, or gloves and sleeves, with control of the part), the part is insulated from the worker and from other conductive objects, or barehand rules in 1926.964(c) are met. Glove users also wear sleeves unless other exposed parts are insulated (installed without upper-arm exposure), and put gloves and sleeves on and off only outside reach of the MAD. So far as other site safety conditions allow, workers take positions where slipping or receiving a shock cannot carry them into parts at a different potential; between 600 volts and 72.5 kV, without gloves, cover-up, live-line tools or barehand methods, they must work where they cannot reach into the MAD. Connections go to the deenergized part first, disconnections take the source end off first, and loose conductors stay clear. Within reach of exposed energized parts, rings, watches, keychains and similar conductive articles are removed or made nonconductive unless harmless. Flames and arcs: the employer assesses which employees face flame or arc hazards and, for each arc-exposed employee, reasonably estimates the incident heat energy (broad system-area estimates allowed; Appendix E methods are deemed compliant). Clothing that could melt or ignite and keep burning is banned (acetate, nylon, polyester, rayon, polypropylene unless treated or worn so the hazard is removed). The outer layer must be flame resistant when exposed to contact with parts above 600 volts, when an arc could ignite nearby flammable material or molten metal or arcs from faulted conductors could ignite clothing, or when the estimate exceeds 2.0 cal/cm2. Above 2.0 cal/cm2, arc-rated clothing and equipment at least equal to the estimate cover the whole body, except hands (rubber gloves with protectors, or at no more than 14 cal/cm2 heavy-duty leather gloves of at least 407 g/m2 (12 oz/yd2)), feet (heavy-duty work shoes or boots), and head (1926.100(b)(2) head protection below 9 cal/cm2 single-phase open air or 5 cal/cm2 otherwise; with an arc-rated faceshield of at least 8 cal/cm2 below 13 or 9 cal/cm2 respectively; and for single-phase open-air arcs head and face protection may be rated 4 cal/cm2 below the estimate). These duties began January 1, 2015 (estimates) and April 1, 2015 (FR above 2.0 cal/cm2, arc-rated gear). Fuses with a terminal above 300 volts, or exposed parts above 50 volts, are handled using tools or gloves with a rating for that voltage; expulsion fuses above 300 volts also need Subpart E eye protection, a rated tool and standing clear of the exhaust path. Rules on exposed live parts also govern work close to covered (noninsulated) wires. Non-current-carrying metal parts count as energized at the highest exposure voltage unless inspected and found grounded. Load-break opening devices must interrupt, and closing devices safely carry, the current involved.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.