Wrist straps and ESD footwears are the first line of defence against electrostatic charge build up on the human body. They are designed to carry away this charge as soon as it is generated. At the same time the wrist strap/footwear must remain electrically safe for the user. Thus, it is important to test every wrist strap/footwear regularly.
In order to protect sensitive electronic components, the maximum wrist strap resistance should not be more than 10 meg ohms and footwear resistance should not be more than 35 Mega ohms. On the other hand, the resistance should not be less than 0.75 Mohm as protection to the wearer from dangerous levels of voltage and current flow.
The wrist strap and the footwear tester checks these parameters under actual operating conditions with the strap on the wrist or footwear to the foot. It clearly indicates whether or not the wrist strap/footwear system is safe to use.