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Cap305

Got (literally) shocked on the boat today

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Cap305

So, I had filled up the ballast bags with the throw over the side pump. Finished up, started the boat and then realized that I couldn't find my surf rope so I reached between the starboard side hull and the ballast bag thinking that it may have fallen down there. Hit the wet carpet under the ballast bag with my index and middle finger and zzzzap. Fingers were numb for a min or so. Guessing that I've got a grounding issue here somewhere which I'm sure will be an absolute joy to find. Anyone else ever had something like that happen to them? Any obvious places to look other than the engine grounding point? All systems function properly and I all gauges functional. Volt read out is 13v on gauge. Thanks in advance.

p.s. I'm wondering now if this was the cause of my periodic idle issues due to the computer flaking out somehow due to a bad ground.

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shawndoggy

This is surprising because it has been my experience that 12v (or 13 or 14.4) can't really shock you. I mean grab both terminals of your battery if you want to test. i guess i've never tried that with wet hands, but I don't think the outcome is any different. You don't have an inverter on board do you?

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Cap305

Nope, no inverter. Agree with you on the touching the terminals on a battery but I've also accidentally had a wrench cross the positive with the negative and that definitely lit up a nice spark. Unfortunately I'm not going to be near the boat for a couple weeks due to vacation. I'll give everything a good check before I take it out again.

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2003qcwakevlx

Maybe a shock from your spark plug wiring.

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williemon

Wrench between bat posts has 0 resistance so you get lots of amps. Your body has resistance, less if it's wet but produces less amps so still surprised that 12v dc would produce a shock but I could be wrong. I don't remember that part of my electronics training from back in the day.

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shawndoggy

Nope, no inverter. Agree with you on the touching the terminals on a battery but I've also accidentally had a wrench cross the positive with the negative and that definitely lit up a nice spark. Unfortunately I'm not going to be near the boat for a couple weeks due to vacation. I'll give everything a good check before I take it out again.

sure it can make a spark. I mean my BBQ will light with a spark circuit that's activated with a AA battery. but just because it will spark doesn't mean it will shock you.

The laying the wrench across the terminals thing won't shock you but it will weld the wrench to the two terminals and turn red hot and probably eventually start a fire (i.e. only to be tried on episode of mythbusters). But it's heat that would burn you not shock you.

I've been totally knocked on my butt from a shock from a bad sparkplug wire (on a motorcycle). But that's with stepped up voltage, not 12v. Again not saying you are wrong, but if you are looking for things that could shock you on the boat, AFAIK, it's really only the coil or spark plug wires.

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ibelonginprison

Yeah, I was about to say - if you don't think a 12 volt system will shock you, yank a spark plug wire off of a running car by the boot and hang on to that sucker for a hot minute.

It's gonna find a ground somewhere to arc to, and it ain't a happy tingle when you find out that it's "you."

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shawndoggy

Yeah, I was about to say - if you don't think a 12 volt system will shock you, yank a spark plug wire off of a running car by the boot and hang on to that sucker for a hot minute.

It's gonna find a ground somewhere to arc to, and it ain't a happy tingle when you find out that it's "you."

but that's more like 4-5000 volts right? Doesn't the coil step up the voltage?

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ibelonginprison

but that's more like 4-5000 volts right? Doesn't the coil step up the voltage?

What I'm saying is... all that wapowie came from a car... that only has a 12 volt battery in it. Cars can shock the snot out of you.

You want extra pain, snatch one off a truck with an MSD ignition. lol

Edited by ibelonginprison

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Cap305

The hit I got was more like what you'd get from a low power pasture fence wire vs what you guys are describing with a spark plug. I've brushed 110V wires while working on light fixtures at the house before and it was much less force/pain than that sensation. Just odd really.

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shawndoggy

The hit I got was more like what you'd get from a low power pasture fence wire vs what you guys are describing with a spark plug. I've brushed 110V wires while working on light fixtures at the house before and it was much less force/pain than that sensation. Just odd really.

I've never tried it wet... but I know that putting a 9v battery on your tongue definitely gives a little zzzzzz. maybe it's the reduced resistance from being wet?

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martinarcher

I've been nailed by 13.8 volts before in college doing car stereos. I had a buddy with a Crossfire amp running a pair of JL subs in his trunk that would cut out. I had him playing the subs fairly hard and suspecting a loose connection I kicked off my flip flops and hopped in the trunk (we had pulled the spare and mounted the amp in the tire well so I'm standing on the steel trunk floor). I pick up the amp and jiggle it to see if the subs would cut out and as I do I realize the amp ground wire is loose. The subs hit hard and I got a pretty good tingle through my feet into the car. I dropped the amp when I got buzzed and quickly exited the trunk. I had him shut it down and we re-terminated the ground wire and he never had trouble with it again. That day was a hot humid summer day and I know my feet and hands were sweaty which I'm sure helped make me a better "ground" for the amp. I'm sure I didn't get hit with much current as it's pretty hard for that low of a voltage to shock you but I know what i felt!

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Rednucleus

There's amps (current) and there's volts, Really high volts (even 1,000's) with low amps shocks w/o killing. Relatively low volts (like house 110v) with high current can kill you dead. If the shock was similar to a hot wire fence, I would agree look harder at your ignition system. That's very high voltage from the coils and would conduct nicely through wet carpet. Standard 12v battery voltage would probably not be felt based on your description of how you got zapped.

Disclaimer - Damn't Jim, I'm a veterinarian, not an electrician (but I play one on TV!) - AND all of the above must be true and correct cuz you are reading it on the internet!

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williemon

Now that I remember, working with car batteries in a car that was off I still got a burning sort of tingle in my leg where my bare skin touched the chrome bumper so now I do suspect the 12 volt system.

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mainekneeboarder

A 12 volt system can give you a tingle, happens to me all the time on race cars laying across a roll bar while doing wiring. I am also the type that has learned not to play with plug wires while a car is running as I WILL get zapped where another guy MAY get zapped. I have friends that tell me I'm crazy for thinking I can feel a tingle off a 12 volt wire, but I can assure you it DOES happen! To me its more of a tingle then a shock, but not sure I have ever tried it wet.

Next time a bunch of ur buddy's are around take an ohm meter and hold the ends in each hand and check the resistance, the difference in some people is kinda amazing.

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Bozboat

This is surprising because it has been my experience that 12v (or 13 or 14.4) can't really shock you. I mean grab both terminals of your battery if you want to test. i guess i've never tried that with wet hands, but I don't think the outcome is any different. You don't have an inverter on board do you?

we used to lick 9 volt batteries, they will shock you

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shawndoggy

we used to lick 9 volt batteries, they will shock you

they will (airquotes) "shock" you like a handshake buzzer. Not "shock" you like "I gotta go lay down for a while."

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chris4x4gill2

Any chance it was a static charge caused from rubbing your hand against the balast bag?

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Cap305

Kinda doubting it Chris. Definitely wasn't a shock-type discharge, more of a low level continuous current thing. I'm away from the boat for a couple weeks due to vacation and such but will definitely take a multi-meter with me next time just to see if I can duplicate it and/or detect any kind of charge.

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Cap305

Also, one thing I thought about was my Perko switch. I added it a couple years ago and it's fixed to the same board as my amps which in turn is fixed to blocks glued to the hull. I wonder if I'm getting some sort of low-level current from this since I didn't isolate it from the hull with any additional insulation.

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Lance B. Johnson

So try this it will help you figure out the problem. Lick your right index finger and touch the positive post. Lick the left index and touch negative. Seriously. I do this with all my students that are afraid to hook up a battery charger :). At worst your going to feel a very slight tingle. At best you won't feel a thing.... There you go you ruled out most of your scenarios....

I thought I got shocked once when I bent over and touched something... It was just a nerve that sent a tingle down my arm and into my back.... Getting old.

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justgary

Get all good and sweaty and then lay your forearm across the battery posts. Using any part of your hand or wrist is cheating. Spraying your arm with water is cheating. Everybody go try it and report back.

Edit: Don't do this with a large object above the battery. You might bang your arm on it when you jerk it back.

Edited by justgary

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Rednucleus

Get all good and sweaty and then lay your forearm across the battery posts. Using any part of your hand or wrist is cheating. Spraying your arm with water is cheating. Everybody go try it and report back.

Edit: Don't do this with a large object above the battery. You might bang your arm on it when you jerk it back.

Caution - if you have manly hairy arms this could result in a flash fire and bad smell!

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JasonK

Big difference if the boat is running or not guys. His boat was running.

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shawndoggy

Big difference if the boat is running or not guys. His boat was running.

why would there be a big difference?

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