Definition(s)
Grounded (grounding)
Connected (connecting) to ground or to a conductive body that extends the ground connection (NFPA 780).
Source: API RP 545 Recommended Practice for Lightning Protection of Aboveground Storage Tanks for Flammable or Combustible Liquids, First Edition, October 2009. Global Standards
Grounded (earthed)
Connected to earth or to some conducting body that serves in place of earth.
Source: API Recommended Practice 14FZ, Recommended Practice for Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class I, Zone 0, Zone 1, and Zone 2 Locations, Second Edition, May 2013. Global Standards
Source: API RP 14F, Design, Installation, and Maintenance of Electrical Systems for Fixed and Floating Offshore Petroleum Facilities for Unclassified and Class 1, Division 1 and Division 2 Locations, Fifth Edition, July 2008. Global Standards