Electrostatic Discharge (ESD) is probably something you have experienced many times. It occurs when an electrical charge on one non-conductive surface discharges onto a conductive surface. For example, if you shuffle your feet across a carpet, particularly one that contains man-made fibres, a static electrical charge builds up in your body. As soon as you touch something that conducts electricity, such as a metal handle, the electrical charge in your body discharges rapidly to the metal object. You feel an electric shock, which is harmless. However if ESD occurs between sensitive electrical components, such as computers, it can cause serious damage. Since ESD occurs mainly between people and other objects, if you work on sensitive electrical equipment you need to wear a special wristband connected to ground so that static electricity doesn't build up.
Use static electricity built up in your own body: it's a great way to check ESD using a multimeter. Practice discharging ESD first so you know electricity builds up. Rub your hands or feet on a carpet as this produces friction which converts to electricity and is stored until you touch something metal. Touch something metal, but ensure it's not an item connected to an electrical supply: a metal door handle is ideal. You get an electrical shock as you touch the metal object.
Use a digital multimeter to check for ESD. Digital multimeters use their own battery to power the display and they retain the measurement unlike analogue multimeters that return to zero once there is no electrical current. As ESD occurs in a microsecond, you need to be able to retain the reading.
Select the multimeter to read "amperes." This measures the amount of electrical current passing from one object to another. Attach the metal prong on the end of the black wire from the multimeter onto the metal object before you build up static electricity. Use a strip of tape to keep it attached. Hold the plastic cover protecting the metal sensor on the end of the red wire from the multimeter in one hand. Don't touch the metal prong on the end.
Rub your feet or other hand on the carpet you practised on earlier to build up a static charge. Touch the prong on the end of the red wire from the multimeter using a finger on your other hand. Your get an electrical shock as ESD passes from your body, through the multimeter and onto the metal object.
Read the digital multimeter display. It tells you the amperes produced from the ESD. If you want to check the voltage then simply alter the setting on the digital multimeter to read volts and then repeat the process.
Things you need
- Insulating tape