Capital Punishment P Bass

[SGD Lutherie]

Every house I ever lived in had the mains grounded to the water main pipe. So it's a local ground.

I think the real issue is electricians miswiring outlets. I've also seen this in every house I've lived in. In my current apartment, which is in an old house, many of the outlets are installed upside down, and along with that the common and hot are reversed (and on top of that all the facets in my current apartment are backwards with the hot on the wrong side!)

You can pick up an inexpensive outlet tester at places like Radio Shack that will diagnose if you have any problems. The most common problem are the common and hot being swapped, and often the ground pin is not connected to anything, except the box!

 

[SGD Lutherie]

This is serious, as others have said. Here is a great article on the subject. I followed his advice after stumbling upon this a few years ago.

http://www.guitarnuts.com/technical/electrical/safety/index.php

Right, and exactly what I have been saying all along.

The easiest way to protect yourself is to install a cap between the ground wire from the bridge and ground. You you have metal knobs you might want to do the whole shielding isolation as in the article.

 

[NKUSigEp]

I'm tired of my 72 Pbass electrocuting me all the time. I've recieved several very minor burns on the inside of my right arm lately. Feels alot like a small bee sting but its starting to get annoying. Any ideas on what could be causing it?

Electrocution: death caused by electric shock.

So you die every time you play your bass?

 

[scottbass]

I'm telling ya guys...the bass is trying to kill me! I just wonder why its doing this, I can see if it was just at my house and my amp....hmmm

IT'S NOT THE BASS!!!:scowl:

There should be NO significant electricity flowing up the instrument cable from the amp to your bass. If there is, THERE'S SOMETHING WRONG WITH THE AMP AND/OR THE WIRING (CIRCUIT).

Sorry about yelling, but it's so freakin' obvious! You're getting significant electricity delivered to you. Your bass itself is not a source of electricity. Therefore, the electricity is coming up your instrument cable from your amp, either due to a fault in the amp itself or a mis-wired AC circuit.

 

[SGD Lutherie]

Someone needs to yell!

I said it was not the bass several times, but no one is listening to me!

So keep shouting!

Unless your bass plugs right into an AC outlet, it can't shock you, but your amp can, and will.

The only rewiring that will stop your bass from shocking you is removing the string ground, but then you will probably have a noisy bass.

Best bet is to install a cap between the bridge wire and ground. The cap will block DC current.

 

[Parabolic Box]

Maybe the OP has had one shock too many.

 

[Cernael]

So. What do we know?

The OP gets shocked.

When?

P bass -> his amp -> his house? Yes.
Schecter -> his amp -> his house? No.
P bass -> other amp -> other house? Yes.

I agree that, if there's a current flow through the lead, it's not the bass. So, how to test that?
By playing without the lead. Does the bass still shock when played unplugged? In that unlikely case, it IS the bass.
Or, plug the bass in, and tap a voltmeter between the strings and likely grounds in the room; water taps, radiators, etc. PLEASE WEAR RUBBER GLOVES FOR THIS, AND BE CAREFUL! Don't touch both the bass and ground to yourself.

If the meter doesn't react, either you haven't found a valid ground, or it's the bass.


BTW, if the amp and/or wall socket is messed up, so that AC is flowing through the lead, how does a cap in the bass help? It does if it's DC, but isn't that more a ground loop thing?

 

[SGD Lutherie]

Where does one get a neon bulb outlet tester as described above?

They used to sell them in Radio Shack, but as we all know, they are getting out of the electronics business.

I did a quick Google for "neon circuit tester" and found these:

Twin Probe Circuit Tester GET-100A

[Invalid or Expired Link Removed]

More here: [This invalid link has been removed]

How is it used to test the voltage between mic and bass?

Hold one probe to your strings, and touch the other on the mic you will be using, or what ever other gear, or even just a water pipe or something grounded. If it lights up, your ground is reversed.

Isn't it actually amperage that kills?

Current... yes, high voltage with low current isn't too bad, but you can still get a good jolt, as with a stun gun, or even a static electric discharge. But a high current source, even at a lower voltage, like a car battery, can be dangerous.

I once measured about 90 volts between my bass and a microphone after I had gotten a nasty shock! After that I always carried a neon circuit tester and later a multimeter. I didn't check the current.

Also an outlet tester like this is handy:

Ideal Outlet Tester, 3 Prong, Checks Ground Circuit

Here's a couple of good articles I found just now

http://www.guitar-repairs.co.uk/electrical_safety_on_stage.htm

http://www.geocities.com/SunsetStrip/Studio/2987/phasel.html

 

[wb20]

+1 on the plug-in tester thing, though $38 is ridiculous. Lowes / HDepot / Harborfreight have them for well under $10.
Invalid Link Removed
These are really handy for instant outlet diagnosis. If the wiring in your house is old & bad (like 3-prong outlets installed where there's not any ground hooked up) you can install GFCI outlets on 2 wire circuits to protect you from getting killed. This doesn't fix the problem, but it keeps you from getting electrocuted

You can also buy a cheap multi-tester for about $6 at HarborFreight. If you know how an outlet is supposed to be wired you can test them with the meter, but the plug-in is still a nice quick&dirty convenience. Set it on high range AC, like 200V. Find a ground. If the plug-in tester says the outlet ground is good, stick one lead in the 3rd prong ground of the outlet the amp is on. Otherwise, metallic plumbing may be a good ground reference. Faucets hooked up with plastic supply lines are not. Now probe the amp. Do the exposed metal parts show voltage? With a cheap non-auto-ranging meter, you'll need to click the range down. Probably goes like 200 / 20 / 2 volts. You'll probably see a fraction of a volt diff. 40V and above you can feel with dry skin, and more can be lethal.

You can also use it probing between any two objects to detect a delta-V. If the outlet checks out, find a metal chassis ground on the amp; probe between it and the strings or other metallic parts of your bass. It should be zero. But it sounds like your amp needs to be trashed or fixed.

 

[wb20]

I think the real issue is electricians miswiring outlets. I've also seen this in every house I've lived in. In my current apartment, which is in an old house, many of the outlets are installed upside down, and along with that the common and hot are reversed

The "upside down outlet" thing really annoys me too. But there is some logic to it. It may even be in the NEC. The thought is that if the outlet cover plate comes loose (they are metallic in industrial apps) it is better to land on the ground prong (ie: upside down outlet) rather than short across the hot & neutral.

This may also just be a maintenance electrician's excuse to annoy us.

 

[SGD Lutherie]

Where I'm living now, there's no rhyme or reason... some are upside-down, and others are not. Same with the facets.

The real annoyance with upside-down outlets is when you have one of those plugs that hands down at a right angle.. and now it's up. And also with wall warts.

I think these things are clearly made to have the outlet the other way around.

I think it's just sloppy work combined with laziness.

 

[detracti]

...

However......

I took both my basses to a few friends houses and plugged in to their amps, one house is less than a year old and he has no problems with his pbass through an older ampeg combo as well as a carvin stack. The Pbass did the same thing to me through both amps at his house as well as the other guys house through a crate combo....I'm telling ya guys...the bass is trying to kill me! I just wonder why its doing this, I can see if it was just at my house and my amp....hmmm

That's just weird. The only thing it could be is the bass itself, since you've eliminated your amp and the house wiring as culprits.

What's the make and model? Has it been customized?

I'm wondering if it is somehow wired like one of those gag/novelty chewing gum packs that give you a jolt.

 

[mongo2]

I took both my basses to a few friends houses and plugged in to their amps, one house is less than a year old and he has no problems with his pbass through an older ampeg combo as well as a carvin stack. The Pbass did the same thing to me through both amps at his house as well as the other guys house through a crate combo....I'm telling ya guys...the bass is trying to kill me! I just wonder why its doing this, I can see if it was just at my house and my amp....hmmm

The P bass is passive. Where do you think this mysterious voltage is coming from?

 

[SGD Lutherie]

The P bass is passive, there are no voltage sources in the bass. Where do you think this mysterious voltage is coming from?

It's coming from the amp. It ALWAYS comes from the amp, or other AC powered gear. His other bass doesn't do it, but he didn't mention if that's an active bass, as they often don't have the strings grounded (especially with EMG's). With no string ground, you wont get a shock.

Just because more than one amp caused a shock doesn't mean all the amps, outlets, etc., were not the problem, as it's a pretty common problem.

I played with the same bass and amp combination for over 10 years (Ibanez SoundGear 5 and GK-800RB) and most of the time it was fine, and some times I got shocks. When I had EMG's in the bass I had no shocks.

There's a simple fix that was mentioned about a half dozen times.

 

[TJBass]

Ok, took me awhile to get things together and have the time to check everything out. Picked up a basic circuit tester and checked the bass against the closest ground (kitchen faucet). It lit up.

Went to friend's house and checked that, it lit up, and the same goes for the third house. Everything lighting up.

Yes the Schecter is active, and no it did not light up when checked.

So, I'm hoping the amp is not the cause and that its just the house wiring. I'm going to bring a friends amp over and see if it still lights up.

 

[TJBass]

would this resolve the problem?

 

[sound of bass]

It's coming from the amp. It ALWAYS comes from the amp, or other AC powered gear. His other bass doesn't do it, but he didn't mention if that's an active bass, as they often don't have the strings grounded (especially with EMG's). With no string ground, you wont get a shock.

Just because more than one amp caused a shock doesn't mean all the amps, outlets, etc., were not the problem, as it's a pretty common problem.

I played with the same bass and amp combination for over 10 years (Ibanez SoundGear 5 and GK-800RB) and most of the time it was fine, and some times I got shocks. When I had EMG's in the bass I had no shocks.

There's a simple fix that was mentioned about a half dozen times.

Ive been on several calls (paramedic) where a person was zapped from thier instrument /amp, nothing too serious, except this one guy was playing near an open window during a storm.....you guessed it, he got wailed! The amp took most of it. Sped his heart rate up dangerously but was fine after an hour or so. Just a reminder these things do happen and can be fatal. My tip is "dont do that".

 

[Bassamatic]

This thread has brought up a really good point - I need to add an outlet tester and an AC checker to my gig tools. It is really easy to have your amp and bass on one circuit and the mic and mixer on another circuit with a different polarity!

Playing bass is GREAT FUN, but not worth the chance of losing it all.