[TCML] top load and photography (tripod grounding)
bartb at classictesla.com
Wed Mar 5 20:37:05 MST 2008
> But it's implied that after Peter grounded the tripod, the "tingle" went
> away. This would mean that the camera was originally not at ground
> potential, but Peter's body was.
Likely neither was at ground potential, but the potential difference
between Peter and the camera was lowered when the tripod was grounded.
No problem with that. The tingle was simply an indication of a potential
difference (several thousand volts).
> The same theory that "standard" safety grounding is based on applies
> here as well. If a conductive object is in contact with your body, if it's
> grounded then the current should take the path of the grounding conductor instead
> of your body.
Of course it should, but that isn't the issue.
> I don't think being in bare feet would make much difference WRT strikes from
> the topload. But it might save your life if you get in contact with anything
> on the primary side (or the line side!). Besides, you might step on
> something painful which causes you to jump or fall into live equipment.
> Who does this stuff in bare feet, anyhow?
Just an analogy of grounding your body (bare feet is a good way to do
it). Standing in water, hooking up your body to a grounded conductor,
> That's a valid point, but I bet even if the tripod wasn't intentionally
> grounded you'd still be in bad shape if you took that strike. I don't think a
> ground wire to the camera would make much difference.
It certainly could make a difference. Ever notice how bright those
steamers get when they contact ground?
> If I was out in the middle of a field holding a lightning rod, I'd
> really prefer to have the lightning rod solidly grounded, not free floating in my
> hands. Almost a moot point? Better to stay out of a bad situation!
Ok. After the lightning rod is solidly grounded, and you grabbed it in
one hand (camera click) and got jolted on your other hand? Now what?
Could it be that because the rod was grounded so were you, and you
became a nice target? Yes...
> FWIW, I remember when I was running my 4" coil in the garage, and the
> thing reached out with a 4' strike to a big polyethylene trash barrel. One
> strike only! Apparently it was attracted to the static surface charge on the
> barrel. Once it "sucked all the charge" off the barrel with a hot strike, it
> never tried to hit it again. So even if you're conscientiously wearing
> well-insulated footwear and staying away from grounded objects, you might still make a
> highly attractive target to a strike.
Could happen. Again, stay out of harms way.
Grounded targets are obvious, but that is only one aspect. There are
also hv transients that ride on ground.
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