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grounding

Contents:

  1. electrified aquarium
    by daleman/ccrs.emr.ca (Paul Daleman) (23 Jan 92)
  2. (M) Voltage "leaks" again
    by patti/hosehead.intel.com (Patti Beadles) (26 Feb 92)
  3. Induced voltages
    by fhd/panix.com (Frank Deutschmann) (Tue, 24 Nov 1992)
  4. Induced voltages
    by exualan/exu.ericsson.se (Alan Malkiel) (24 Nov 92)
  5. Tank grounding
    by booth/hplvec.LVLD.HP.COM (George Booth) (Sun, 25 Jul 1993)

electrified aquarium

by daleman/ccrs.emr.ca (Paul Daleman)
Date: 23 Jan 92
Newsgroup: rec.aquaria


I read with interest comments from
laurence-at-cco.caltech.edu (Dustin Lee Laurence)
regarding electrified aquariums. I also once read a magazine article on this
subject (FAMA Oct 1990, p62). As an electrical engineer, I think I'll throw
in my opinion on this subject.

Adding a ground to solve the problem of electricity leaking into the water is
not the right to go. It may save the owner from being shocked, but it will make
things worse for the tank inhabitants.

The problem is not the voltage level of the tank, but current flowing through
its occupants. Just as birds perched on a high voltage hydro wire don't notice
their bodies are 27,000 volts above ground potential, the same is true in an
aquarium. If one appliance is leaking electricity, but there are no paths to
ground (a glass or acrylic tank is a very good electrical insulator), then no
current will flow, and the fish would not know that they were not at ground
potential.

Thus everything will be fine until a grounded electrode is placed in
the tank. Now AC current will flow between the bad appliance and the ground.
This is how people are electrocuted in a bathtub when a radio or hair drier
plugged into the wall falls in. Current flows between the appliance
and the drain pipe (which is a good ground). If the victim's heart is in the
path of enough current flow, it will stop beating.

Since the conductivity of salt water is much higher than tap water, it would
probably be harder to electrocute marine fish. The fish will not enjoy
the current passing through its body though. Long term exposure to
even minute currents is probably not good.

On the flip side of this, the electrode grounding the tank will protect the
owner better, because most leaking current will flow through the electrode
(the least resistive path) and not the owner.

The solution to the electrified tank problem is to find out which components
are the culprits and repair or replace them.

I think it would be a good idea for owners to periodically check their tanks for
electrical leakage. The easiest way to do this is to put a voltmeter (AC)
between the water and ground (a good electrical ground - eg wall socket ground).
If you get a reading of more than a few volts, I would worry. **SEE NOTE BELOW
ON VOLTMETER**

I don't think it is necessary to set up an elaborate system to
protect you and your fish from electrical malfunctions. Hopefully it is rare
that a component leaks electricity into the tank. A shock from a fish tank
would not likely be fatal, but if it is strong enough, it will cause
an uncontrollable desire to remove one's arm from the tank as rapidly as
possible. This is where serious injury and damage to the tank / hood etc. could
occur.

If you want to make a shock-proof tank, hook all accessories that could possibly
cause a problem to GFI sockets (Ground Fault Interrupters). Then hook an
electrode from the water to one of the GFI ground terminals. If anything
begins to leak, the corresponding GFI will cut off power.

**A NOTE ON VOLTMETER READING OF TANK POTENTIAL**
When I first tried to measure the voltage of my tank I was surprised to get a
reading of 32 volts. By selectively turning off my equipment I determined
that every electrical piece of equipment near my tank would cause this
potential. It turns out this was because I was using a very high impedance
electronic voltmeter. The tank water acts as an antenna and picks up the 60 Hz
electric field transmitted by nearby appliances. Because the water is so well
insulated, the reading given by a high impedance voltmeter will be
extraordinarily high. The current that the tank can supply at this voltage is
EXTREMELY small. I then connected a 100k Ohm resistor between the tank and the
ground -- the voltage dropped very near zero. If the problem was a faulty
appliance, I would expect no change in the voltage reading with the addition of
a resistor that large.

SUMMARY
- If you are worried about both you and your fish being shocked by electrical
aquarium appliances, use GFI sockets and a ground electrode. There are a few
aquarium related products out there that will do this for you if you don't like
wiring.
- If you are just worried about yourself (or can't afford/be bothered with
GFI's) then ground the tank. You will know you have a problem when your fish go
nuts or die.
- If you haven't had a good shock in the last few years and can't be bothered
with this grounding stuff, you can probably get along fine without it. If you
ever get zapped though, don't come running to me!

-- Paul Daleman     -P.S. I'm leaving my tank ungrounded for now...


(M) Voltage "leaks" again

by patti/hosehead.intel.com (Patti Beadles)
Date: 26 Feb 92
Newsgroup: rec.aquaria

In article <2800130-at-hplvec.LVLD.HP.COM> sylvia-at-hplvec.LVLD.HP.COM (Sylvia Budak) writes:
>     I would like to ground my tank.  My question is how is the electrical 
>connection made?  One would think it would require some metal coming into 
>contact with the water.  Somehow purposely introducing a metal lead into the
>water seems a little like putting a little poison into the tank.  How have
>other people done this?  Is there one metal much safer than others to use 
>for this? [...]

Since Packard of California is no longer selling their grounding probes,
I'll briefly describe the design of the one that I have.

It's a small rod (1/2" or so) of 316SS (a special kind of stainless steel
that is saltwater resistant), connected to a thin wire, which goes to a 
regular three-prong plug.  The two flat prongs of the plug (hot/neutral)
have been removed and replaced with pieces of plastic, so that they are
non-conductive, but will hold the plug in place in a socket.  I haven't
taken it apart to verify this, but the wire is obviously connected to the
ground prong.  (Otherwise the device would be useless. :-)

This method requires that you have properly wired outlets.  If you don't, 
you can run the other end of the wire to a cold water pipe instead.

The steel rod to wire junction is coated with plasti-dip, to ensure that
no water gets into it.  (I believe it's copper wire, so this is important.)
FWIW, Packard used 22-gauge wire (I think) so that if there is a major
current leak, it will vaporize the wire instead of potentially causing a
fire.
-- 
patti-at-hosehead.hf.intel.com |  I don't speak for Intel, nor vice-versa.
   75555.767-at-compuserve.com |
             (503)-696-4358 |  A1: Yes, I'm the one with the big fishtank.
or just yell, "Hey, Patti!" |  A2: A lot, a lot, yes you can see it sometime.


Induced voltages

by fhd/panix.com (Frank Deutschmann)
Date: Tue, 24 Nov 1992
Newsgroup: rec.aquaria


Just a thought on a (relatively) cheap source of titanium: your local
high-performance bicycling shop.  Titanium has gotten real popular
with cyclists these days (lightness, strength, and cool flat grey
color), so bike shops that stock performance bike parts are starting
to carry lots of titanium.  Now, you are probably thinking that all
titanium means mega-bucks; however, I think that if you simply aquired
a titanium bolt (like a stem binder bolt) for ~$5 or so, that would do
the job.  Mounting the bolt, and attaching a ground to it may be
tricky, but could work if you built a little hangar above waterline,
or went through the tank/sump/whatever.

I'm not sure the trouble is worth the modest savings over a commercial
unit, but just a thought...


-- 
-frank
(fhd-at-panix.com)


Induced voltages

by exualan/exu.ericsson.se (Alan Malkiel)
Date: 24 Nov 92
Newsgroup: rec.aquaria

Re: Titanium bolts.

If you use a titanium bolt you still have the problem of attaching a wire
to it which will be of different composition, which can cause its own
problems.  Not to mention you now have an ugly bolt hanging in your tank.

As an alternative, call West Marine, 1-800-538-0775, and order part number
196907, Monel seizing wire, for $8.95.  "Top quality, non-corrosive, pliable,
slightly magnetic, 33 feet".  (quoting the catalog)

Disclamer:  I have not tried this wire to ground my tank.  Nor have I bothered
to measure my tank's induced voltage.  I know nothing about the problems that
induced voltage is supposed to cause.  But I do sail boats in salt water!  

---
Alan Malkiel               |   e-mail exualan-at-exu.ericsson.se
Ericsson Network Systems   |   alt.   exu.exualan-at-memo.ericsson.se
MS - C06                   |   memo - EXU.EXUALAN 
PO Box 833875              |   phone - (214) 997-6672
Richardson, TX 75083-3875  |   "Opinions - worth exactly what you paid"


Tank grounding

by booth/hplvec.LVLD.HP.COM (George Booth)
Date: Sun, 25 Jul 1993
Newsgroup: rec.aquaria

In rec.aquaria, zach-at-hyper.esd.sgi.com (George Zachary) writes:

    Does anybody have any experience using tank grounding equipment like
    Sandpoint's Solution Ground or Sandpoint's Voltage Eliminator or Coralife's
    product?

We use the Solution Ground in our discus tanks and can attest to the fact
they reversed a case of fin rot.  We now have them in all our tanks. 

-------
George


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