Re: Let's talk about single coil equipped guitars shielding
I think honestly it depends on the guitar and the rig, not just how you mod it. My Lite Ash Strat is bone stock, and I've never touched the pick guard (nor will I unless I have a **** good reason). It is going to hum in single coil mode regardless. However, it's ironic that on my '72 Twin Reverb, at home, directly plugged into my Lite Ash, I get no hum in single coil modes, or if I do, it's not noticeable. At church, with my multieffects, stage lighting, monitors, music stand lights, etc, I get some, but I use noise suppression so it's not very noticeable.
Some cheaper guitars may require mods.
Still, for what it's worth, you can't really call the ground on an AC circuit with two output wires a "ground". If you're really that paranoid, maybe you should consider playing in a Faraday Cage

. Just kidding. But still, if you're that paranoid, here are some ideas. First, remove all electronics you don't need, and all that you are wearing (i.e. don't carry cell phone, and don't play near LCD or CRT devices like computer monitors or television sets). Second, check your home or stage wiring and make sure it's not dirty. Some old houses have horrible hum problems, for example. Third, use three prong plugs (i.e. grounded) for everything you can. Fourth, connect the chassis of all your stuff together (i.e. a wire running from your effects pedal(s) to the chassis ground on your amp) to equalize ground potential / capacitance. Or play barefoot on a metal floor with all your pedals on the metal as well

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I'm no expert on this, but I've had USAF training on electrical circuits, and I can tell you that aircraft computer boxes all ground through the chassis and all those chassis electrically are connected so that they "ground" to each other. Works great even when the aircraft is flying and isn't really "grounded".
But anyways, like I said, I'm no expert, so the above is just my opinion.