how much does it cost to ground an outlet
1 On average a portable GFCI outlet can cost anywhere from $15 to $35 while an outlet that is installed within the wall can cost $6 to as much as $20 for a commercial grade model.2  There are different types of GFCI outlets available and the price for the outlets usually varies depending on these difference. These are 2 to 5 socket outlets that have 25 amps and 125 volts. 2  GFCI outlets which have a 3 wire 15 amp outlet adapter can cost $10 to $12. 3  For example, the highly rated Leviton 7899-W 20 Amp, 120 volt GFCI outlet retails for $11 to $21.