Transient current

[Franklin]

I've measured current going thru my hull before so I know it goes thru it. Now it's either going thru via the paint or it's going thru the glass and yes, it was a very low current, but none the less, it was current.

No all my bus bars have rubber betten the bar and the mounting bolts and all the bars I see at the marine stores do too, but not the automotive stores.

You can throw all kind of theories at me but it doesn't add up to real world.

 

[Ross]

I've measured current going thru my hull before so I know it goes thru it. Now it's either going thru via the paint or it's going thru the glass and yes, it was a very low current, but none the less, it was current.

No all my bus bars have rubber betten the bar and the mounting bolts and all the bars I see at the marine stores do too, but not the automotive stores.

You can throw all kind of theories at me but it doesn't add up to real world.

Franklin, You say that you have measured the current through your hull. I have several questions for you .
What was your method for the measurement?
What voltage did you apply to the fiberglass?
Did you take into consideration the through hulls?

In the real world you should be able to describe a test method and the results and I should be able to duplicate your results.
I know that glass is non-conductive. I know that polyester resin when cured is non-conductive. So, Please tell us by what method you measured a flow of electrical current through a fiberglass/polyester laminate.
I respect most of your posts but in this regard I find your reasoning flawed.

 

[tommays]

If you use even the better brands of CHEEP meters you can go down all kinds of false paths chasing electric ghosts


Now if you use a Fluke or = when chasing tiny stray currents

 

[Don12364]

Many have remarked about Witzend's comment that it is not possible to get a shock from 12V DC.
This may be true for dry skin which has quite good insulating properties but any break in the skin allows current into the body where it is conducted quite readily.

How do I know? I had wet hands and picked up a heavy 12V battery. It was an awkward lift from the locker and my hands were wet. I took firm hold of the battery and each of my thumbs were pressing down hard on each battery post.
I got quite a belt which could have caused injury had I not been able to let go - which happens in DC electrocution cases.
Have never done that again!

 

[John Nantz]

Whoooa - Good post Donelex

Glad I read about it rather than learning it the hard way!

Fortunately I use "plastic" gloves or a battery carrier when handling batteries to try and avoid getting holes in any more of my good shirts or pants.

The only thing worse than getting a good shock is the tongue-lashing from ones wife about getting battery acid holes in formerly good clothing!

Speaking of electric fences, we, too, had horses with a 12V electric fence. Seeing how long one could hold on to the wire was not fun. Don't stand in wet grass!

As for "the other boat" with the generator running, maybe he had electrical wiring problems???

 

[Ross]

Re: Whoooa - Good post Donelex

John , Your 12 volt electric fence was powered by 12 volts just as the ignition system on your car is powered by 12 volts but the charge delivered to the fence is several hundred or thousand volts in very short pulses.

 

[jibes138]

Glass as a conductor

It seems like the whole semiconductor industry is based on this concept. Maybe 100% pure glass is not a conductor but glass filled with impurities can be. Also how about the water that is in the glass, that certainly conducts, then there is the layer of water,dirt, mold, mildew, that is all over the outer surface of the laminate that conducts. You don't need much of a conductive coating, it only has to connect sequential atoms of conductive material to conduct, much smaller than can be seen. Also I seem to recall an old formula from electrical engineering or physics that proved that all current is carried on the outer surface of a conductor, so the state of the interior is not important. This is one source of batteries losing power, there is a leakage path across the terminals cause by water, dirt, etc. One good reason to keep the battery clean.

 

[Ross]

It seems like the whole semiconductor industry is based on this concept. Maybe 100% pure glass is not a conductor but glass filled with impurities can be. Also how about the water that is in the glass, that certainly conducts, then there is the layer of water,dirt, mold, mildew, that is all over the outer surface of the laminate that conducts. You don't need much of a conductive coating, it only has to connect sequential atoms of conductive material to conduct, much smaller than can be seen. Also I seem to recall an old formula from electrical engineering or physics that proved that all current is carried on the outer surface of a conductor, so the state of the interior is not important. This is one source of batteries losing power, there is a leakage path across the terminals cause by water, dirt, etc. One good reason to keep the battery clean.

Some of this is true for very high voltages and very high frequencies. But they aren't making any tubular wire for low voltage applications. as far as contamination is concerned we used to go to extreme efforts to insure that the glass case on our 100,000 megohm resisters were clean and stayed that way. You could in effect short them by rubbing a finger from one end to the other.