Re wired my bass and now I get shocked

Discussion in 'Pickups & Electronics [BG]' started by Stevemx25, Aug 12, 2020.

  1. Stevemx25


    Aug 12, 2020
    Hello! New to forums but searched everywhere and could not find anything about my current bass dilemma. I re wired my awesome 100 dollar Craigslist bass (fender knock off) to be simply pickups and the jack. The first time I forgot to install the bridge ground and got shocked a bit and had slight heart palpitations. After re installing the bridge ground it just shocks me less then before. Playable yes but I still get a hum when my hands are off the strings which I’m assuming means there is still a ground issue somewhere. Also I took the knobs off and have holes in pick guard from them. Yesterday I soldered a ground from the jack to the small amount of foil tape on the pick guard from the factory and it changed nothing. Anyone out there have any advice or knowledge on this subject? I was thinking maybe add copper tape inside the pick guard and try grounding to that but who knows.
  2. dwizum


    Dec 21, 2018
    I'm going to let my safety nerd side show here for a minute and suggest that you unplug all of your equipment, take the amp to a qualified tech, and have an electrician come to your house and check that your outlet is properly grounded. Do not diagnose the amp or wall outlet yourself, do not pass go, do not collect $200. If the amp and your home's wiring both check out fine, that's great - come back and let us know, and we can help you solve any issues on the bass itself.

    This could feasibly be a trivial and harmless issue with the wiring you've been working on in your bass, or something silly like static electricity building up because you're shuffling feet on your carpet and then discharging through your grounded bass. But it could also be a grounding issue with your amp or the plug you've plugged it into. Ground issues in mains equipment attached to guitars often show themselves as the musician getting a shock when they touch metal on the equipment and their body becomes the ground path - exactly what you are describing. The classic way this manifests itself is a guitarist touching their strings and a microphone at the same time, when one of those is grounded properly and the other isn't - the guitarist becomes the ground path between the ungrounded equipment and the grounded equipment. But it can also show up as your body becoming a path to the literal ground (the surface you're standing on) for just one piece of ungrounded equipment.

    To be clear - a ground issue in an amp or the outlet it's attached to can kill you or burn your house down. Let's rule those potential issues out before anything else so we know we're operating from a safe basis.
    BazzaBass, DTRN, smarthound and 9 others like this.
  3. MVE


    Aug 8, 2010
    The problem is in the amp or, more likely, the outlet (aka wall holes) (Seinfeld reference)

    Do you have a meter? You should test the wall holes first. There are lots of youtube videos on how to do this.

    The big slot is neutral, round hole is ground, and little slot is “hot”. (That’s means its the one that can hurt you, but that’s ASSUMING it is wired correctly and from your description, it probably isn’t. So tread carefully, and only work with one hand, so any shocks don’t go across your chest.)

    You should see about 120 volts AC across either the (little slot to big slot) or (little slot to round hole).
    There should be continuity between big slot and the round hole.

    If there is AC between the big slot and round hole OR no AC from little slot to round hole, that would explain why your guitar is shocking you.

    Note: if any of this seems confusing or you are not comfortable testing this or you don’t enjoy getting shocked, call a professional.
    jchrisk1, DTRN, gebass6 and 2 others like this.
  4. Stevemx25


    Aug 12, 2020
    I have tried a few different amps at different locations with the same result. Putting the ground to the bridge helped a lot but that hum (when I’m not touching the strings) and very minimal shock still exist. Would a wireless system solve this? Also it looks like someone was already messing with the wiring as the wire under the bridge looks to have been moved several times and the solder on the pickups is mismatched..
  5. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Please listen to us. This isn't a problem with your bass. You should never have shockable-level voltage out at the bass. If you do, it means that either your amp is mis-wired, or your house wiring is messed up. If you are getting shocked through different amps at different locations, this probably means that somewhere in your house wiring, the Hot and Ground legs are connected reversed. This is a dangerous condition. Fire, injury, death. Get this checked out and fixed pronto. We don't want to hear that you got electrocuted while playing around with the bridge ground on your bass.
  6. Derndingle


    Jul 24, 2020
    This reminds me of a time many years ago in high school, our band room had a set of stairs coming down from the main hall way. The rhythm section for jazz band setup next to the stair well. I was playing through an old Fender Bassman amp that belonged the school and had my left hand on the neck and grabbed the metal railing next to the stairs with my right for some reason and it shocked the crap out of me. I don't know if it was the amp or the bass or the school's wiring, but it made enough of an impression that I remember it 30+ years later. I've gotten a few other electrical shocks at gigs over the years, but that one was probably the worst.
  7. Stevemx25


    Aug 12, 2020
    Ouch! Thanks for all the advice. I can double check my outlets but come to think of it.. the place I rent I went over the outlets with an electrician so they should be good. Maybe my removal of all the knobs in the bass and the direct wiring stuff wasn’t done quite right. Anyone els ever remove the tone and volume knobs successfully?
  8. bassinflorida

    bassinflorida turn that dang thing down

    Jan 27, 2014
    Tampa, FL
    Do you WANT to die?
    BazzaBass likes this.
  9. The only way there's enough potential at your bass is if your power wiring is screwed up in your amp or or your wall.

    I'd put your experience getting shocked over the electrician giving the place a once over. I'm an electrician.
    BazzaBass, gebass6, LBS-bass and 6 others like this.
  10. Stevemx25


    Aug 12, 2020
    I played the bass when I got it (before tinkering with it) and it did not shock me or hum at all. It was only after I re wired it did it start with the zapping (which is very minimal now..more of a fuzzy feeling). And it’s even less since putting the bridge ground back in. Some other threads said to just straight up wire the pick ups to the jack and disregard the bridge ground... but then I think I became the ground
  11. Slater

    Slater Leave that thing alone.

    Apr 17, 2000
    The Great Lakes State
    That doesn’t matter. For whatever reason, you were lucky enough to not get shocked before you rewired the bass. There shouldn’t be enough juice traveling through your bass to shock you at all. There is an electrical issue with your amp or home.

    Oh yeah…there’s also this…

    mikewalker and Ruknrole like this.
  12. The list of things that could change how badly you get shocked is large. The only constant thing is the voltage that causes the pain is coming from the 120v.
    Ruknrole likes this.
  13. Bruce Johnson

    Bruce Johnson Commercial User

    Feb 4, 2011
    Fillmore, CA
    Professional Luthier
    Once again, this problem has nothing to do with your bass. You should never have 110v potential inside the bass. The only way that can happen is if the ground circuit of the amp and building is somehow running at higher voltage than the actual ground (stakes in the earth).
  14. Stevemx25


    Aug 12, 2020
    Hmm.. I play my normal rig in the same spot without any issues.. just seems to be this particular bass. My daily driver has active pickups though. Excuse my ignorance as I gave up on engineering school right before electricity and electronics began
  15. JRA

    JRA my words = opinion Supporting Member

    Stevemx25 , you joined this site to get some answers = it would be goofy of you not to take the advice of some experts...right?

    get to it and get back with us! welcome to talkbass. ;)
  16. Stevemx25


    Aug 12, 2020
    Exactaly! Thanks for the input everyone. Luckily I will live to play another day and have my outlets checked out. Maybe I will also take this monstrosity into work tomorrow (where the outlets SHOULD be good) and see how she fairs. I also have one of those mini portable 3w amps.. might be wise to test my wiring jobs there first?
  17. JKos

    JKos Supporting Member

    Oct 26, 2010
    Torrance, CA
    @Stevemx25 ,
    Listen to us. Nothing you've done to bass is the cause of getting shocked. Something else is wrong!

    - John
    DTRN, MVE, Tommy V and 3 others like this.
  18. It's possible that good, solid shielding and a couple of pots are reducing the impact of the flaw to where you don't notice it, but it's still a flaw that needs addressed.
    Ruknrole and JKos like this.
  19. RichSnyder

    RichSnyder Columbia, MD Gold Supporting Member

    Jun 19, 2003
    A bass wired in any way should not shock you. Your problem is not your bass. Have an electrician check your wiring and if that's good, your amp is screwed up. You may get buzzing or not if wired improperly, but there is no scenario where a mis-wired bass would shock you. I'd like to see future posts from you, please don't screw around with this. You can get a receptacle tester on Amazon, at Walmart, Home Depot, etc if you want to test the outlet before contacting your landlord. They will cost about $8.00 and it's a good thing to have in your gear bag to test outlets when you go to a gig. Older bars can definitely have sketchy wiring.
    DTRN, gebass6 and Ruknrole like this.
  20. IS your life insurance paid? Is the beneficiary made clear?

    WILL the EMT's know how to notify your next of kin?

    IS your will made out?

    DO you have one of those blood-type info bracelets?

    IS 911 on your speed dial?

    Do others have keys to your house?

    BECAUSE you will not listen, but here goes again: You can rewire your bass 20 different ways, you can have an orangutan do it if it'll make you feel better, but regardless there is NO WAY any of that is generating 110v (or worse) and giving you heart palpitations, it's in the amp or downstream in the house wiring. PERIOD.

    Get it checked. I've seen someone almost killed by bogus wiring, way past what you encountered. DON'T be the next one.
    mikewalker likes this.
  21. Primary

    Primary TB Assistant

    Here are some related products that TB members are talking about. Clicking on a product will take you to TB’s partner, Primary, where you can find links to TB discussions about these products.

    Sep 25, 2021

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