A GFI is an abbreviation for a Ground Fault Interrupter. It is a specially designed outlet normally used in locations where moisture can accumulate, such as kitchens, baths and laundry areas, to protect you from electrical shock. A GFI measures the resistance on the “positive” and “negative” loads connected to it, and if there is more resistance in either of the two loads, the GFI trips. The GFI has a built-in circuit breaker to reset once the problem has been resolved.