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Guitar pot grounding; Wire or shielding, which is best?
If you've considered modding or replacing your guitars wiring, you might have considered your shielding or grounding methods too. If you've ordered a replacement wiring loom, whether that's from myself or from another trusted supplier you will have likely noticed that there are ground wires between the pot casings. Exact method or wire used possibly may vary between maker, but generally speaking there will be some form of ground connection present.



More often than not, us wiring loom makers/suppliers will pre-solder ground wires to your new loom to ensure that you have a secure/solid ground connection as ultimately we don't know your exact guitar and what it might have already. It may have no shielding at all, but it could also have existing shielding so you may wonder what to do in regards to the ground wire(s), whether you leave those in situ, or opt to snip them off and ultilise shielding plates or shielding tape for example. So, which is better? The answer most likely comes down to what your guitar cavity/pickguard already has, or if a new project, what you plan to use. But ultimately, continuity is best! So whichever method achieves good continuity for your points of ground, is best. If you look under your pickguard or peer into the control cavity, inspect to see whether it already has a shielding plate or tape in the areas where the components will mount. On Strats for example this might be a full aluminium plate like the one photographed below, or even a partial one just in the pots/switch area. For a Les Paul, more often than not the pots are just mounting right up to the cavity without any shielding, and a Telecaster for example of course has the metal control plate. So there are number of things to look out for.



If you have shielding plates or tape already in place, or plan to use these, then in theory you do not need a ground wire in between each pot as the plate/shielding will take care of it for you. The shielding plate/tape in theory will provide you with sufficient connection between those components for solid ground continuity. But to know for sure, I would advise that you have a multi-meter to hand to ensure continuity; As I have come across scenarios during my time doing repairs that damage/wear over time may affect shielding tapes effectiveness. Scenarios where the shielding tape hasn't been applied correctly so isn't providing continuity, and I have also found that sometimes even bad quality plating (the chrome etc plating on a Tele control plate for example) can cause continuity issues so couldn't rely on the control plate alone. So I feel it's always best to just do a super quick test to know for certain that the plate/tape is doing it's intended job well. If it is doing it's job well, and has continuity, then by all means, you can simply rely on that as your method of grounding the pot casings and you won't need the little ground bus wire(s) between the pots pre-soldered onto a harness. 



Most multi-meters will have a setting for testing continuity, where this setting is located or exactly how it looks might differ between meters/brands, but the symbol is standardised. So you'll want to look for something like this (what the arrow is pointing to) -



It normally displays this to the user via an audible 'beep'. So first step will be to mount your parts, via the shielding plate or tape and grab your multi-meter. Set it to the continuity test setting and methodically test between each component. Perhaps starting by placing one lead from the meter on the shielding plate/tape, and touching the other one on each pot casing. Basically you just need to test between the points of ground, so pot casings, shielding tape/plates, switch housings and if already pre-soldered, the jack ground/sleeve too for good measure. If you get a nice clear audible beep (or however it displays on your specific multi-meter) then you have continuity between those points of ground. Here's some photo examples of me testing continuity of this Strat loaded pickguard, which has a full aluminium shielding plate attached so I was testing it without a separate ground wire between the pots/switch. 







The same methods would apply if it was a Telecaster control plate for example, or any other guitar for that matter with shielding or some form of control plate where the pots mount to/through.



If your guitar has none of these though, so pots mounting straight to a plastic pickguard with no foil shielding or plate, or pots mounting straight through the body wood like the photo example above, then keep your ground wire(s) pre-soldered between the pots in situ. But if you have shielding, grab a multi-meter and test it before assuming you can rely on it. Just in case there are continuity issues to address. As I have briefly touched on, I have had ocassions when working on guitars in the workshop, where the foil shielding on the back of a pickguard etc was worn/damaged, or it was applied poorly resulting in no continuity. So those occasions it's better to replace/remove that shielding foil for example. 



So you've fitted your new wiring loom/harness, you have discovered you have existing shielding in the guitar, tested it and are happy with it, but your new harness has a ground wire between the pots. Then you can simply snip off, or de-solder depending on what you prefer to do, then you're good to go and no concerns of potential ground loops. But if you don't have any shielding at all, then you'll be safe in the knowledge that the pre-soldered ground wire between the pots will keep things working quietly.
I hope this helps with your repairs and modifications to your own guitar(s). 

James.

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26 April, 2023 by James P Gascoigne

Comments

Thomas H.

Thomas H. said:

Very interesting and helpful!
I‘ve recently added an aluminium plate below the pickguard of my jazzmaster and I will cut the ground wires between the pots and switches. Where would you connect the ground of the pickups? Still on the volume pot?

James Gascoigne

James Gascoigne said:

My pleasure, Thomas! Glad it has been helpful.
Yeah you can certainly still solder your pickup ground wires to any pot casing, that will be absolutely fine:)

Thomas H.

Thomas H. said:

Thanks, James, for your specific reply.

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