Grenada runs on 230 V at 50 Hz, with sockets following Type G. At 230 V the supply matches what UK and European appliances expect, so no converter is needed.
The same socket system is used in Saint Lucia and Dominica, so one adapter covers all of them. Travelling further to the British Virgin Islands, the United States and Anguilla means a different adapter. Across North and Central America this setup is fairly rare: 3 of 31 countries.
Protective earth
Grounded socket systems are common
Protective earth is standard in Grenada; your adapter should carry it through.