WORKING ON ENERGIZED CIRCUITS

1-15 · Remove all rings, wristwatches, bracelets, and similar metal items before working on the equipment. Also ensure that your clothing does not contain exposed metal fasteners, such as zippers, snaps, buttons, and pins. · Do not tamper with interlock switches; that is, do not defeat their purpose by shorting them or blocking them open. · Ensure that equipment is properly grounded before energizing. · De-energize equipment before attaching alligator clips to any circuit. · Use only approved meters and other indicating devices to check for the presence of voltage. · Observe the following procedures when measuring voltages in excess of 300 volts: Turn off the equipment power. Short-circuit or ground the terminals of all components capable of retaining a charge. Connect the meter leads to the points to be measured. Remove any terminal grounds previously connected. Turn on the power and observe the voltage reading. Turn off the power. Short circuit or ground all components capable of retaining a charge. Disconnect the meter leads. · On all circuits where the voltage is in excess of 30 volts and where decks, bulkheads, or workbenches are made of metal, you should insulate yourself from accidental grounding by using approved insulating material. The insulating material should have the following qualities: It should be dry, without holes, and should not contain conducting materials. The voltage rating for which it is made should be clearly marked on the material. The proper material should be used so that adequate protection from the voltage can be supplied. Dry wood may be used or, as an alternative, several layers of dry canvas, sheets of phenolic (resin or plastic) insulating material, or suitable rubber mats. Care should be exercised to ensure that moisture, dust, metal chips, and so forth, which may collect on insulating material, are removed at once. Small deposits of such materials can become electrical hazards. All insulating materials on machinery and in the area should be kept free of oil, grease, carbon dust, and so forth, since such deposits destroy insulation.