ELECTROSTATIC DISCHARGE PRECATIONS

thereafter, he touched the ground lead and received a serious shock. He was treated for minor burns on the palm.” VOLTAGES ABOVE 300 VOLTS All the safety procedures for measuring voltages below 300 volts also apply when you are measuring voltages above 300 volts. However, the big difference when measuring voltages above 300 volts is that you must NOT hold the test probe while the equipment is energized. Instead, you must attach the test probes while the equipment is de-energized. (Refer to table 3-5). ELECTROSTATIC DISCHARGE PRECAUTIONS Electrostatic discharge (ESD) can destroy or damage many electronic components, including integrated circuits (ICs) and discrete semiconductor devices. Since certain devices are more susceptible to ESD damage than others, warning symbols, shown in figure 3-1, are now used to identify ESD-sensitive (ESDS) items. The widespread use of integrated circuits led to the development of special training courses in miniature/microminiature (2M) circuit repair. Certified 2M technicians are trained in procedures for reducing the causes of ESD damage. The procedures are similar for all levels of maintenance. If you are certified in 2M repair, you should follow the protective measures in table 3-6 to help prevent ESD damage. Remember, although many sources of electrostatic charge are of little consequence during most daily activities, they become extremely important when you work with ESD material. If you are not certified in 2M repair, do not attempt to repair any of these circuits. For further information on handling ESD materials, refer to Introduction to Microelectronics, Navy Electricity and Electronic Training Series (NEETS), Module 14, NAVEDTRA 172-14-00-84. Q3. What is the FIRST step in taking voltage measurements below 300 volts? Q4. What is the major difference between using a test probe to measure a voltage above 300 volts and using it to measure a voltage of 300 volts or less? Q5. What dangerous effect to electronic components are EDS precautions designed to reduce or eliminate? ELECTROMAGNETIC RADIATION HAZARDS The electromagnetic spectrum encompasses everyday uses from commercial power to medical 3-5 No. Safety Precaution 1 ALWAYS follow all preliminary safety procedures for measuring voltages below 300 volts before beginning your measurement. 2 ALWAYS make sure that the equipment you are working on is de-energized. 3 ALWAYS follow the tag-out procedures. 4 ALWAYS discharge all high-voltage capacitors with a shorting probe. 5 ALWAYS attach the ground probe of the measuring device first. 6 ALWAYS secure the other probe of the measuring device to the test point to be measured. 7 ALWAYS make sure that the measuring device is set up for the voltage level and polarity to be measured. 8 ALWAYS energize the equipment under test, make the measurement, and then de-energize the equipment. Table 3-5.—Safety Precautions For Measuring Voltages Above 300 Volts