Potential sources of EMI are all around us: cell phones, radios, computers, and fluorescent lights are just a handful of common sources. To compound the issue, the human body is a natural antenna for electromagnetic interference.
To eliminate the EMI that a player inherently adds to the signal, a wire is attached in such a way as to connect the guitar strings to the instrument’s electronic ground.
While the player touches the strings, this wire effectively cancels out the noise that a players body adds to the signal by giving it a path to ground. This crucial length of wire is known as the “String Ground Wire”.