My bass amp shocks me!!

[BadExample]

Once, I got shocked through my headphones while practicing at home (scary 100+ year old rental house with questionable wiring). I heard a buzz through the headphones, and over about 10 seconds, it got louder and louder and then I got shocked in both ears. Scared the crap out of me. Never used phones with that amp again, and never had any other issue, ever, with that amp. Still no idea what happened there.

Family notice any personality changes after that?

 

[pebo]

But you are testing for AC. It doesn't matter which color goes where.
If you don't know that you shouldn't be doing the test at all.

You may not learn anything about house wiring in an electronics course.
Electronics and electrical wiring are related in that they both involve wires and electrons, but they are different disciplines.
Becoming an electrician is a different set of courses from electronics.

Don't be that guy who gets hurt because he knows just enough to be dangerous.

This is absolutely correct. Lack of knowledge as well as using incorrect tools designed for home electronics is very dangerous when used on mains voltages.

As an electrician and a electronics trades person, if i am live testing a power socket in a home or the main feed to a large factory, i always use the correct rated meter, insulated gloves, have my CPR training in date, a competent observer who is trained in live rescue standing near me with a rescue kit and is willing to rescue me from a switch board. Im also wearing fire retardant clothes, working with a one handed technique that if i do get a shock it hopefully wont travel through my body.

I find it amazing the lack of respect some have for electricity. The same respect needs to be shown on 240v, 110v as it does to hight voltages.

 

[pbass62]

This is absolutely correct. Lack of knowledge as well as using incorrect tools designed for home electronics is very dangerous when used on mains voltages.

As an electrician and a electronics trades person, if i am live testing a power socket in a home or the main feed to a large factory, i always use the correct rated meter, insulated gloves, have my CPR training in date, a competent observer who is trained in live rescue standing near me with a rescue kit and is willing to rescue me from a switch board. Im also wearing fire retardant clothes, working with a one handed technique that if i do get a shock it hopefully wont travel through my body.

I find it amazing the lack of respect some have for electricity. The same respect needs to be shown on 240v, 110v as it does to hight voltages.

I am also a licensed industrial electrician. PLEASE have it checked out enough said!!

 

[Dean N]

Family notice any personality changes after that?

No. But, it was right around then that the voices in my head started advising that I kill everyone.

 

[bumperbass]

PSA: Those $5 or $10 outlets testers are fine for the most part.
But they will NOT detect an outlet with a reverse polarity bootleg ground (RPBG).

Reverse Polarity Bootleg Ground Testing

They will not detect CPBG (Correct Polarity Bootleg Ground) wiring either. That's when, in a 2 wire circuit, the white is jumpered to the green contact on the outlet.

 

[Killed_by_Death]

You can probably fix it yourself, but be sure to update your life insurance policy first.

 

[byacey]

Any electronics technician worth his salt should have a through understanding of premises wiring too. This is 1st year training material.

The important questions still haven't been answered: What is the floor you were standing on when this occurred, a concrete
floor under the carpet? And were you wearing any sort of footwear providing insulation? Leather soled shoes don't provide very good insulation.

The bottom line is for you to have received a shock, current must flow from an AC source, through your body to an earth ground. This means some part of your body must have been grounded and touching an AC potential at the same time. Many older tube amps with a 2 wire AC line cord have a .05 mfd cap between the AC line and the amp chassis. This cap can certainly pass enough current to deliver a very noticeable shock to a grounded human body.

 

[Relsom]

Yes, but both amps doing it indivated a bad circuit or two in his house.

Don't you just love autofill.
Anyway, OP just because you have a 3 prong outlet doesn't mean you have proper grounding. But I'm thinking that your hot and neutral are swapped somewhere on that circuit. If you are comfortable with a meter, you should read anywhere between 115vac and 122vac with one probe on the round (Ground) receptacle hole and the other probe on the short (Hot) slotted receptacle hole. If you read the voltage between the round one and the longer (Neutral) slotted one, your polarity is reversed. And FYI...the neutral and ground wires both connect together on the ground buss back at your panel. If you have any doubts at all about performing this test safely, call an electrician.

 

[FugaziBomb]

It's interesting that as many electronics enthusiasts as there are, most would rather tell you off or tell you to go to someone certified than volunteer to impart some knowledge...

Thing is, if someone gives you the wrong advise in this situation, it might end up killing you. The folks telling you to take it to a pro are actually doing you a solid and giving you the best advice, for sure. Sometimes this place seems snarky, but it usually comes from a good place.

 

[byacey]

And FYI...the neutral and ground wires both connect together on the ground buss back at your panel. If you have any doubts at all about performing this test safely, call an electrician.

Additionally, just because the neutral and ground busses are tied together doesn't mean that they are both connected to a solid, low impedance earth ground. The whole neutral / ground system could be floating with respect to earth ground. The main distribution panel should be bonded with heavy copper wire to the copper plumbing pipes and to a ground rod driven into the dirt outside.

Because this has happened with two different amps, I suspect something is definitely wrong with the AC wiring in this building.

 

[swafran]

This is God telling you not to replace the bass player with a pedal!

Exactly. And She's pretty pissed off.

+1 get an electrician to the room to properly ground outlets.

 

[BadExample]

Additionally, just because the neutral and ground busses are tied together doesn't mean that they are both connected to a solid, low impedance earth ground.

It should also be noted that neutral is not safe in a live circuit. There is a reason it is a separate wire from ground. It passes current. In a faulty circuit, it can become particularly unsafe. An open circuit between neutral and the ground reference at the breaker box will cause it to go to full AC power if there is an appliance (like a turned on light) in circuit. I'm sure there are plenty of dead hacks that can testify to this.

 

[Bigbri]

I don't currently play much bass since I play regular guitar in the project I'm currently in. Since we don't have a bassist at all right now, we have a pedal that plays the backing tracks that include the bass and we plug it into my bass rig, which is an Ampeg SVT-450 and two 8 ohm cabs. Several years ago the gain knob got knocked off, leaving the metal underneath, and since I consider it mostly cosmetic and don't change the gain when playing actual bass guitar, I never replaced it. But we've had to change the the gain more often since we play the pedal though it. During the last month or so, every time I try to change the gain while the amp is on it delivers a shock that while all it does is jiggle my elbows and piss me off, I don't like playing around with any electrical shock and I'm aware of the possibility that it could get worse. I've even experimented with using a different amp and another outlet in the same room, and the same thing happens. I had an electrician look at it and he replaced one of the outlets, but I'm not sure he fixed it because I think he probably just saw that it was upside-down (with the ground prong on top) and replaced it. I tried testing the ground with a multimeter and it seemed fine, but I'm inexperienced and learned to do it from watching a tutorial, and I'm not sure I did it right. I also tried using the hot multimeter probe on the gain knob to see if it picked anything up, and it stayed at zero. This issue is just weird to me because my guitar amp has never done this, just both bass amps. And it seems to only happen when it has been on for a little while and is quite loud. Also when we don't have the pedal, I plug in my laptop, and I get shocked through the keyboard! I have not yet taken my amp to a technician, but that will be the next step. Also, the house was built in the '40's. I'm guessing grounding may have been different then. Thoughts are appreciated!

On a side note, when I first got this Ampeg the fan would not turn on, but from suggestions on this forum I was able to fix it since the fan connector turned out to be plugged in upside-down. I'm super grateful for that help, and I hope for more of the same! Thanks!

My house was built in 57 and it needed a breaker box upgrade to 200A and some of the outlets have breakers in them as well because of a grounding issue. You can also have very "dirty" power which is unstable and can shorten the life of electronics. As far as I know your house should be grounded with very thick copper cable bolted onto one of the water pipes. The danger is when your playing an electric guitar and you touch something like the mic. There should be a ground wire from the jack to the bridge of your guitar. Ace was walking down the stairs on kiss's stage prop, grabbed the metal railing and almost killed himself. That was the motivation to write "Shock me". I have an old tube amp that apparently has "the death cap" so at this point I haven't used it. If your getting any kind of current coming through take the head in and have it checked.

 

[Old Garage-Bander]

My house was built in 57 and it needed a breaker box upgrade to 200A and some of the outlets have breakers in them as well because of a grounding issue.

Those are not circuit breakers in your outlets. Those are Ground Fault Interrupters.

They do not trip on a circuit overload like a breakers does.
And they are not used because you have grounding issues.
They are used to protect against grounding issues.

If you have a ground fault the GFI will trip and shut off the outlet and any other outlets upstream from them.
For the GFI to not trip, the ground at the outlet must be good... not have any issues.
GFI's are required mostly around wet areas like kitchens, bathrooms and laundry facilities.

 

[pcake]

btw, having three prong plugs means nothing. we lived in an apartment with 3-prong plugs, but it turned out the third prong wasn't attached to anything at all - they got 3-prong outlets and only two prongs were attached to any wire at all.

 

[Old Garage-Bander]

btw, having three prong plugs means nothing. we lived in an apartment with 3-prong plugs, but it turned out the third prong wasn't attached to anything at all - they got 3-prong outlets and only two prongs were attached to any wire at all.

YUP! Happens all the time. Old house with no grounding and two prong outlets...
The old outlet gets to where the socket can't hold a plug anymore...
Since you cannot purchase new 2 prong outlets, you replace it with a three hole...
If doing that, the outlet should be marked as not grounded.
It still isn't right, but at least someone else would know not to trust it.

 

[Joe Ty]

Those are not circuit breakers in your outlets. Those are Ground Fault Interrupters.

They do not trip on a circuit overload like a breakers does.
And they are not used because you have grounding issues.
They are used to protect against grounding issues.

If you have a ground fault the GFI will trip and shut off the outlet and any other outlets upstream from them.
For the GFI to not trip, the ground at the outlet must be good... not have any issues.
GFI's are required mostly around wet areas like kitchens, bathrooms and laundry facilities.

You can also buy breakers with the GFI's installed in them. I used one for the circuit I ran to my brewery. It works (DAMHIKT). They claim a longer useful life than the outlet variety.

 

[pcake]

YUP! Happens all the time. Old house with no grounding and two prong outlets...
The old outlet gets to where the socket can't hold a plug anymore...
Since you cannot purchase new 2 prong outlets, you replace it with a three hole...
If doing that, the outlet should be marked as not grounded.
It still isn't right, but at least someone else would know not to trust it.

ah - that explains it! i did wonder why that apartment (which was built just post WWll) had all those new prongs with the ground unattached.

 

[BadExample]

As far as I know your house should be grounded with very thick copper cable bolted onto one of the water pipes.

Old code if I am not mistaken. That fat wire to the pipe should be disconnected at the breaker box. That is if the breaker box is grounded at the service entry. Reason being, if the house struck by lightning and the ground is earthed in two locations, the ground loop can cause a fire,

For the GFI to not trip, the ground at the outlet must be good... not have any issues.
GFI's are required mostly around wet areas like kitchens, bathrooms and laundry facilities.

No, GFI's trip if there is current flow between the hot and earth in the appliance (or circuit beyond the breaker if GFI is at the circuit breaker). This protects you if the appliance has an internal leak to earth; current flow (a few mA's) from hot to earth rather than flow from Hot to Neutral, which is allowed. The idea is to protect you if the flow to ground is through your feet, like in the case of the shocking amp, or it flows out your ass when a fed up wife tosses a hair drier in the shower while you are bathing You have to press the test button to verify functionality. It won't work without a dedicated ground to the outlet or breaker.

btw, having three prong plugs means nothing. we lived in an apartment with 3-prong plugs,

I believe this is actually legal, but would be a good idea to label as OGB stated, and certainly needs to be stated upon sale of the house.

You would not believe what I found in my 100 YO house with "upgraded" wiring.

 

[Old Garage-Bander]

Old code if I am not mistaken. That fat wire to the pipe should be disconnected at the breaker box. That is if the breaker box is grounded at the service entry. Reason being, if the house struck by lightning and the ground is earthed in two locations, the ground loop can cause a fire,



No, GFI's trip if there is current flow between the hot and earth in the appliance (or circuit beyond the breaker if GFI is at the circuit breaker). This protects you if the appliance has an internal leak to earth; current flow (a few mA's) from hot to earth rather than flow from Hot to Neutral, which is allowed. The idea is to protect you if the flow to ground is through your feet, like in the case of the shocking amp, or it flows out your ass when a fed up wife tosses a hair drier in the shower while you are bathing You have to press the test button to verify functionality. It won't work without a dedicated ground to the outlet or breaker.

I believe this is actually legal, but would be a good idea to label as OGB stated, and certainly needs to be stated upon sale of the house.

You would not believe what I found in my 100 YO house with "upgraded" wiring.

The intent of what I said was to explain that you don't install a GFI to fix a circuit that has a ground issue as was previously stated.