On Jan 27, 11:53*am, wrote:
Most people know that dropping a cord or appliance that is plugged into
an outlet into a bathtub filled with water will electrocute the person
in the tub. *Yet, you can drop a low voltage item such as a flashlight
with batteries in the tub and no one will be hurt. *Even a set up jumper
cables connected to a car battery would not likely do anything, or might
just tingle a little (never tried this, but I've handled plenty battery
cables while standing on wet soil in wet shoes and never felt a thing).

Not that I'm planning to test this, but what would happen if a large
capacitor, charged with 200 volts or more was tossed into a filled
bathtub while someone was in the tub? *(By large capacitor, I dont mean
the size, but rather, I mean a large capacity, such as 500 MF or one
Farad or more....).

I see no reason this would ever occur, but I'm just curious.

[NOTE: This could be DC or AC]. DC capacitors are used in electronics,
while the AC type are motor start capacitors.

I don't know what will happen when you toss it in the water, but I
know what will happen when a dead man stick is used to short the
terminals of a large cap charged up to 7 or 8 KV DC.

A dead man stick is a device with a wooden handle with a hooked rod
threaded into the handle and a braided strap with a clip on the end.
It was used to both ground towers and other electrical equipment or to
pull an energized human from said equipment.

At a minimum, shoting out the cap will cause a bang and a spark that
is sure to strike fear into the hearts of most mortal men. In some
cases, it will blow 4 inches of threaded rod out of the hardwood
handle.

We used to do it quite often when I was in the Coast Guard as training/
warning exercise.

We had large oil filled caps (5F) that ran at 15 - 20 KV DC in the
LORAN transmitter buildings. We didn't want non-Transmitter Techs in
the building without one of us present. As new men would arrive at the
station, part of the orientation meeting included a demo where we
would use a Hi-Pot to charge up a cap to at least 5KV DC, turn out the
lights and then short it out with a dead man stick. One time we went a
bit overboard with the Hi-Pot and I was left holding a smoking hard
wood handle while my buddy retrieved the metal rod from across the
room. We grabbed another dead man stick and still got quite a bang out
the cap since it didn't completely discharge before blowing up the
other dead man stick.

That one even scared me!

On Fri, 27 Jan 2012 09:56:12 -0800, DerbyDad03 wrote:
We
grabbed another dead man stick and still got quite a bang out the cap
since it didn't completely discharge before blowing up the other dead
man stick.

Effect of dielectric absorption, possibly? You short it briefly, it
discharges, but then a small portion of the original charge level appears
to come back moments later...

(http://en.wikipedia.org/wiki/Dielectric_absorption)

cheers

Jules

On Jan 27, 2:44*pm, Jules Richardson
wrote:
On Fri, 27 Jan 2012 09:56:12 -0800, DerbyDad03 wrote:
*We
grabbed another dead man stick and still got quite a bang out the cap
since it didn't completely discharge before blowing up the other dead
man stick.

Effect of dielectric absorption, possibly? You short it briefly, it
discharges, but then a small portion of the original charge level appears
to come back moments later...

(http://en.wikipedia.org/wiki/Dielectric_absorption)

cheers

Jules

I am familiar with that phenomenon, although in this situation, I'm
pretty sure it was the result of a partial discharge before the
grounding rod exploded. Obviously I can't proof it, that's just my
guess, based on prior experience with these large caps.

As part of our bi-weekly transmitter maintenance, we would ground the
caps prior to removing the bus bars to get them out of the stand-by
transmitter. Before they were even lifted out of the transmitter, we
always put a shorting cable on them to stop them from charging back up
due to both dielectric absorption and the strength of the signal from
the on-air transmitter.

On the rare occasions that we forgot to do this (newbies!) or noticed
a bad ground connection, we would use a dead man stick to short them
before grabbing them. Even after a few hours, the discharge was
minimal and we might get a little bit of a pop. In the case of the
training demo, which was done in a rather neutral environment (the
mess hall, a 1/4 mile from the transmitter building and tower) the
resulting discharge was quire substantial, much higher than anything
we'd seen in "real life".

On Jan 27, 11:48*pm, wrote:
On Fri, 27 Jan 2012 09:56:12 -0800 (PST), DerbyDad03





wrote:
On Jan 27, 11:53*am, wrote:
Most people know that dropping a cord or appliance that is plugged into
an outlet into a bathtub filled with water will electrocute the person
in the tub. *Yet, you can drop a low voltage item such as a flashlight
with batteries in the tub and no one will be hurt. *Even a set up jumper
cables connected to a car battery would not likely do anything, or might
just tingle a little (never tried this, but I've handled plenty battery
cables while standing on wet soil in wet shoes and never felt a thing)..

Not that I'm planning to test this, but what would happen if a large
capacitor, charged with 200 volts or more was tossed into a filled
bathtub while someone was in the tub? *(By large capacitor, I dont mean
the size, but rather, I mean a large capacity, such as 500 MF or one
Farad or more....).

I see no reason this would ever occur, but I'm just curious.

[NOTE: This could be DC or AC]. DC capacitors are used in electronics,
while the AC type are motor start capacitors.

I don't know what will happen when you toss it in the water, but I
know what will happen when a dead man stick is used to short the
terminals of a large cap charged up to 7 or 8 KV DC.

A dead man stick is a device with a wooden handle with a hooked rod
threaded into the handle and a braided strap with a clip on the end.
It was used to both ground towers and other electrical equipment or to
pull an energized human from said equipment.

At a minimum, shoting out the cap will cause a bang and a spark that
is sure to strike fear into the hearts of most mortal men. In some
cases, it will blow 4 inches of threaded rod out of the hardwood
handle.

We used to do it quite often when I was in the Coast Guard as training/
warning exercise.

We had large oil filled caps (5F) that ran at 15 - 20 KV DC in the
LORAN transmitter buildings. We didn't want non-Transmitter Techs in
the building without one of us present. As new men would arrive at the
station, part of the orientation meeting included a demo where we
would use a Hi-Pot to charge up a cap to at least 5KV DC, turn out the
lights and then short it out with a dead man stick. One time we went a
bit overboard with the Hi-Pot and I was left holding a smoking hard
wood handle while my buddy retrieved the metal rod from across the
room. We grabbed another dead man stick and still got quite a bang out
the cap since it didn't completely discharge before blowing up the
other dead man stick.

That one even scared me!

Damn, I never knew they even made caps that big. *What was the actual
size of that thing? (roughly). *Or is there a photo on the web?

That sounds like quite a charge to see (literally) lol..- Hide quoted text -

- Show quoted text -

They make capacitors big enough to run electric vehicles off these
days.
http://en.wikipedia.org/wiki/Super_capacitor