Ground/earth loop question

[fender3x]

I will be wiring up a Strat-style guitar next and realized that am not sure whether I should worry about a ground loop?

The pickguard has aluminum foil tape stuck to it. If I put one lead of an ohm meter on the foil, and the other on any of the components I see continuity. Normally I would solder a ground wire to each of the pots and switch housings and attach it to the "ring" on the jack. The only guitar I have wired where I did NOT do that was on a Jazz-style bass because everything was attached to a big metal jack plate.

Should I use a ground wire with this? Or should I allow the shielding tape to be the ground wire? My sense is that ground loop is mostly a problem when you have more than one component (e.g. an amp and a pedal) plugged into a grounded outlet, but that it's probably not much of a worry in the control cavity of a guitar. But I wondered if anyone has ever had this problem...and what the "best practice" is.

[McCreed]

I am in no way an expert in electronics, but I can say with some certainty that "ground loops" in passive guitar circuits don't happen.
It is a broadly perpetuated bit of misinformation.

If you're getting continuity through all the components already, you don't have to add the ground wires BUT you CAN without worrying about a ground loop.
You will at least need to run a ground wire from the bridge to somewhere that's grounded in the circuit.
I personally don't rely on my shielding to be my common ground. I prefer the reliability of hardwired grounds. However, I do make sure I have continuity between all my shielded cavities, as I'm shielding to protect against RFI, not solely as a ground point. (hope that makes sense)

[Simon Barden]

It's theoretically slightly better if you can avoid multiple ground circuits, but practically, any extra noise created (or rather, not reduced) as a result is so small to be insignificant against the general background noisiness of guitar and amp circuits. If you had metres, rather than a few cm, of wiring in a guitar, then it could be noticeable. But you don't, so I'd much prefer to be like Marcel and have soldered ground connections between all the pots and ignore the effect of the shielding ground connection.

You could always cut away the shielding foil around two of the controls so that those two pots don't touch the foil, but I really wouldn't bother myself.

[Marcel]

Within a guitar the tiny loop created by running a wire from pot to pot and the copper of aluminum foil between the pots is insignificant. There is virtually nil significant current flow to cause a noticeable voltage drop within the guitar, and no way for it to get out of the guitar to the amp. Inside a guitar the biggest voltages that an amp will respond to will come from the pick ups...

Ground loops between guitar amps and mixing consoles and guitar pedals pose the more serious/annoying problem... These days near everything has an Earth pin on the power plug so for the most part everything has a similar voltage on their exposed metal parts. The earth loop problem rears its ugly head when two connected devices obtain their power from different outlets, and one of those outlets also has a high power consumption load (such as an air conditioner or very high powered amplifier) on its circuit.The voltage drop caused by the high current load (the air conditioner or whatever) is often "seen" by the guitar amp or mixer and presents as 50Hz or 60Hz buzz in those devices. Simplest remedy is place all your music gear on one circuit and series of outlets, and place the high power consumption load (the air conditioner) on its own separate power circuit and outlet. It is the minuscule voltage difference between various audio devices that manifests itself as mains power frequency Earth loop buzz.

In most home studio situations the use of power distribution boards connected star fashion for the entire audio system helps greatly reduce the chance of earth loops ever appearing... In big PA systems and large Pro studios special precautions and techniques are employed to minimize Earth loops.

There are guitar amps that also have a built in anti Earth loop feature. Separating all the amplifier internals from the chassis ground with a 5W 10 ohm resistor will often relegate Earth loops into non-existence. Early VOX amps were all fitted with said 10 ohm resistor. Many modern amps don't, and are engineered and built in a way that the resistor is (hopefully) not required.