67  milliamperes  for  3  seconds AVOIDING ELECTRIC SHOCK The  three  basic  ways  to  prevent  yourself  from receiving an electric shock can be summed up in three words: isolate, insulate, and ground. 1.  Isolate:   Isolate   yourself   from   the   source   of electric  shock.  Make  sure  you  secure  the  power  to equipment before you attempt to remove it. And, make sure   all   electrical   equipment   covers,   doors,   and enclosures are kept in place when you’re not  actually working  on  the  equipment.  If  you  must  leave  live circuitry  exposed,  rope  off  the  area,  post  appropriate signs, and warn your fellow workers of the danger. 2. Insulate:   Make  sure  the  electrical  tools  and equipment  you  use  are  properly  insulated.  Use  only insulated  hand  and  portable  electric  power  tools. Frequently   check   power   and   extension   cords   for deterioration,  cracks,  or  breaks.  Breaks  in  the  insulation of  power  and  extension  cords  cause  many  electrical mishaps. 3. Ground:   Electric  current  always  follows  the path  of  least  resistance.  To  prevent  yourself  from  being the   unintentional   path   to  ground,  make  sure  your equipment is well grounded. This will direct any stray electric current to ground, thereby protecting you from electric shock. A good ground could also protect your equipment from excessive voltage spikes or lightning. For  further  information  on  equipment  grounding,  see Shipboard Bonding, Grounding, and Other Techniques for  Electromagnetic  Compatibility  and  Safety,  MIL- STD-1310  (NAVY). RESCUING  VICTIMS  OF ELECTRIC  SHOCK The first thing to do when you see someone being shocked is to secure the power. DO NOT touch a vic- tim  who  is  in  contact  with  a  live  circuit,  or  you’ll  be shocked too. If you cannot secure the power, use  a dry insulating  material  like  a  rope,   a belt   (without   the buckle),  or  a  wooden  cane  to remove  the  victim  (by pulling,  pushing,  or  rolling)  from  the  live  circuit  or wire. Then, immediately call for medical personnel. If the victim is unconscious AND you are certified to administer    cardiopulmonary    resuscitation    (CPR), begin to do so. The  effects  of  the  electric  shock  can  range  from mild  surprise  to  death.  It  depends  on  the  amount  of current, voltage, and the duration of the electric shock. It’s  hard  to know  exactly  how   a victim   of   electric shock has been affected. More than likely, the victim will be very pale or bluish in color and unconscious. MEASURING VOLTAGE ON ENERGIZED  EQUIPMENT As  an  ET,  you’ll  work  on  energized  equipment. You  will  be  troubleshooting  a piece  of  electrical  or electronic  equipment,  and  the  technical  manual  will instruct  you  to  measure  voltages  or  to  check  signal waveforms   while   the   equipment   is   energized.   But, before  you  hook  up  the  multimeter  or  oscilloscope, there  are  certain  safety  precautions  and  procedures you  MUST  follow.  They’re  designed  to protect  you from electric shock. These precautions and procedures are   divided   into   two   basic   categories:   (1)   voltage measurements below 300 volts, and (2) voltage meas- urements above 300 volts. MEASURING VOLTAGE BELOW 300 VOLTS Most  of  the  voltage  measurements  that  you  will make will be below 300 volts. Almost all of the newer electronic  systems  use  voltages  that  are  less  than  28 volts,  except  for  the  main  input  ac  power.  Here  are some  safety  procedures  you  should  follow  when  you need to measure voltages below 300 volts: 1.   Notify   and   obtain   permission   from   the commanding   officer   (afloat)   or   your   supervisor (ashore)  to  work   on  energized  equipment.  Some commands require you to complete a checklist before doing  this. 2. Study the schematic and wiring diagrams of the equipment   on   which   you’ll   be   working.   Note   the location of the points you will be measuring and, also, the location of any other high-voltage points you should be careful not to measure or touch. 3.  Remove  all  metal  watches,  belt  buckles,  rings (even wedding bands), and any other items that have exposed metal. If you’re wearing a security badge, put it in  your  pocket. 4.   Make   sure   you’re   wearing   electrical   safety shoes, if they were issued, and that you’re standing on insulating rubber matting. If you must insert your hand into the enclosure of the energized equipment, wear a 3 - 3