Myth - Ground Loops in guitars

Myth - Ground loops in guitars

Someone posts a pic of their wiring to an FB group and one of the comments suggests that the wiring contains a ground loop. What the commenter is seeing is a conductive loop via pot casings, foil shielding, a control plate or another conductor. They draw a visual loop in their mind (perhaps confirm continuity with a multimeter) and reach the conclusion that this "conductive loop of ground wire" forms a "ground loop". While this is a loop of grounded conductor, it's strictly and in engineering terms, not a ground loop.

- Can anyone offer a straight answer? Googling won't help either. Since the internet began posts have contained errors and myths about ground loops in guitars. This misinformation is now aggregated by search engines and LLMs and spat out as fact. Even some top pickup makers and instrument builders supply info on ground loops in guitars. These "ground loops" in guitars are alleged to add noise, yet a comprehensive search of the internet has failed to turn up a single demonstration of a change in noise by altering this “looped” wiring. We've created deliberate loops of grounded conductor inside guitars, added a switch to break the loop and there's zero change in noise. We generated and tested many noise types and the fact is, these "loops" are unable to induce any extra noise. Because both ends of these "loops" are grounded, they're at the same potential therefore cannot create a ground loop. (You would require hundreds of turns of wire across considerable area to receive enough noise to be noticeable, in a guitar. Then wire the ends to hot and ground, like a pickup!)

- What is a ground loop? In an electrical system, a ground loop occurs when two points of a circuit are intended to have the same ground reference potential but instead have a different potential between them. This is typically caused when enough current is flowing in the connection between the two ground points to produce a voltage drop and cause the two points to be at different potentials.

You may have created a ground loop when two (or more) devices are connected to mains power at different points. Amps, pedals, audio interfaces, computers; these can all be configured to cause ground loops. These are well understood and there are many solutions available. In all cases two independent references to mains ground are required to form a loop.

A guitar has a single reference to ground, via the output jack > guitar cable shield > and to the mains ground. In a guitar, both ends of any conductive loop are at the same potential. No current can flow. (This is how we shut down one humbucker coil, both ends are grounded, the coil is silent and adds no additional noise)

You can help dispel this myth by not repeating it!