• Convenient connection to power socket.
  Enables grounding through mains earth.

Grounding per EN 61340-5-1 and –2
“An easily accessible dedicated EBP [EPA ground bonding point] for the wrist strap shall be established adjacent to each working area, or working surface. A sufficient number of EBP shall be provided for operators and visitors.” (EN 61340-5-1 section 5.3.3)
“EPA ground cords shall be used to make electrical connections between groundable points and the EPA ground facility.” (EN 61340-5-1 section 5.3.4)
Regarding 1 megohm resistor, “A nominal 1 megohm resistor is commonly used in wrist straps and to ground work surfaces.” [EN 61340-5-2: Section 5.1.1] However, for Working Surfaces, it refers to “it is allowed, when approved by the ESD coordinator, to use surfaces which are “hard ground” i.e. less than 1 X 10^4 ohms to EPA ground.” (EN 61340-5-1 Note 6 of Table 1)
“The EPA ground facility shall be connected to EPA ground and provide a low resistance path to EPA ground (<2 ohms). When available, the mains protective earth shall be used. (EN 61340-5-1 section 5.3.2)