Desco 19219 Ground Hub Monitor, 120VAC, N. American Plug Features:

• Monitors AC Outlet’s Wiring and Path to Earth Ground
  Continuously monitors the path to ground integrity of the outlet meeting the ANSI/ESD S6.1 requirement for verifying wiring orientation.
• Constant Visual Indicator
  LEDs provide a visual indication that outlet is properly wired for grounding purposes of an ESD Control Plan.
• Visual and Audio Fault Alarms
  Alarms activate instantly when a failure occurs, alerting user and supervisor of a problem.
• Six Banana Jacks and Six Screws for #8 Ring Terminals
  Provides numerous groundable points for wrist straps, mats, carts, tools, and other items. May also be connected to other grounding hubs. See Part# 09837
• Made in The United States of America

TB-3049 - Ground Hub Monitor: Operation, Installation, and Maintenance

“The grounding system must be verified periodically at the frequency established in a user defined ESD Control Program Plan.” [Grounding ANSI/ESD S6.1-2009 section 6.2 Verification Frequency]

“All of the grounding conductors from each of the ESD technical elements (excluding level 2 technical elements) used within an EPA shall be terminated at the same electrically equivalent point. The common point ground may be a terminal strip, bus bar or any other convenient configuration that is, within itself, electrically continuous to no greater than 1 ohm measured from point to point with an ohmmeter”. [Grounding ANSI/ESD S6.1-2009 section 5.2.1 Common Point Ground]