Stray voltage/ current, probes... induction,
fixing! 8/11/10
Hey Crew,
<Hi Jimmy>
I have a question re: stray voltage/ current in my marine tank. I have
a very small cut on my finger and I noticed that my 80g marine QT has
stray voltage ( only place I feel it is inside the cut ) the voltage
seemed to be coming from a Mag drive 5 so I changed it out and put a
grounding probe in the sump of the tank. As I was doing my tank
maintenance I again noted stray voltage. This time I thought it was the
titanium heater, which I removed but to no avail. I then removed the
grounding probe and the voltage was gone.
To investigate further I connected the grounding probe to various
outlets that are in the same loop in my garage, put the probe in a
glass of water and noted the stray voltage again ! ( only in the area
of the small cut on my finger ). I tested other outlets inside the
house as well as my main display upstairs ( different system ) and I
detected no stray voltage. It seems to me that there is a small voltage
current in the ground loop of my electrical system that in part grounds
to me or the tank when I use a grounding probe ( i.e. some of the
current preferentially finds the tank instead of the house ground )
that I can only detect through the cut in my finger. I have been told
that my electrical system is properly grounded, and that what I am
experiencing is not uncommon. It is called ground loop interference and
occurs when a grounded circuit has yet another place to ground itself
other than the main grounding pin in to the house. When two or more
devices are connected to a common ground through different paths, a
ground loop occurs. And there is no such thing as a perfect ground. The
problem seem more intense when multiple aquarium devices are grounded
to the same power strip or outlet. ( which makes sense )
If I can feel it through the cut in my finger I imagine the gills of an
animal are probably even more sensitive !
Any suggestions ?
<The first thing to try is adding a grounding rod in the garage (or
right outside). They are right around $15 at a hardware/electrical
store, plus a little for connectors and a wire.>
Thanks
Jimmy
<Scott T.>
Electricity And A Saltwater Aquarium 3/13/10
Hi,
<Hello Shawn>
I have a few questions relative to electricity and the saltwater
aquarium.
I have a Smart UPS that I am using to provide power and back up a 30
gallon fish and invertebrate aquarium. I have the UPS plugged into a
GFCI outlet and various submersible pumps and a heater plugged into the
UPS outlets.
Is this the proper setup when using a UPS? I am not sure if the UPS
outlets are in turn protected by the GFCI outlet.
<Anything plugged into the GFCI outlet will be protected. Do ensure
that your UPS has the capability of handling the wattage/current of the
devices plugged into it.>
I have also measured stray voltage to be around 40Vac by using a
multimeter with 1 probe in the sump water and the other in the ground
of an outlet.
Is this considered a normal reading?
<You should read 0 providing there is indeed a ground wire hooked up
to the outlet ground. If your home is an older home, the old two prong
outlets may have been replaced with grounded outlets to avoid the use
of adapters and it is possible that no ground wire is connected to the
ground terminal.
I would recommend the use of a ground probe even though you are using a
GFCI. Sounds like one of your devices has a voltage/current leak and
I'm sure this device had this problem before you plugged it into
the GFCI and is the reason why the GFCI did not trip. GFCI circuitry
measures current going into the device on the hot leg and looks for the
same current on the return leg (common). If the slightest change
occurs, it will trip. If the device was defective/leaking before you
plugged it into the GFCI, (and this is why I recommend a ground probe
in addition to the GFCI) it would not know the device is defective as
it sees no current change going into and out of it. If the device went
bad/leaked while plugged into the GFCI, it would trip, as it would
sense a current change going into and out of the device.>
I do not have a ground probe and have seen much debate on whether they
actually provide additional safety. Would you recommend a ground
probe?
The tank has been running for 1 year with this voltage present.
<You need to set up your multimeter in the manner you mentioned
above, then unplug one device at a time until you read 0 voltage, once
the culprit device is found, I would strongly recommend replacing it.
Do make sure your multimeter is set to AC voltage and select volts, do
not use the millivolt setting. If you were grounded when you placed
your hands in the tank, the GFCI would instantly trip as it would sense
a loss of current, as much of it would be going through you to
ground.>
Thanks,
<You're welcome. James (Salty Dog)>
Shawn
Re Electricity And A Saltwater Aquarium 3/15/10
Thanks for the advice.
<You're welcome, Shawn.>
I have a new home and the GFCI outlet is new with proper grounding.
However I would like some further clarification regarding your
suggestion that the stray voltage reading should be 0. Do you mean with
a ground probe installed?
<No.>
I made some more detailed measurements and each device was tested
separately without any other devices plugged in. All devices are less
than a year old and are located in my sump/skimmer.
Pump: 18.45VAC
Heater: 16.65VAC
Skimmer: 18.73VAC
With all items powered the voltage is around 40VAC. Based on the above
measurements, I think it is common for "healthy" submersible
devices to induce voltage in water.
<Yes, they are considered inductors and can create stray voltage in
that regard, but if the tank water is indeed grounded, you should read
no voltage, the induced voltage should be going to ground.
There are some UPS devices that use isolated ground circuitry and are
considered above ground devices. Try measuring the voltage without the
using the UPS device and see what you get.>
I will get a ground probe and re-check.
<Great.>
Any further advice is greatly appreciated.
<Not yet. James (Salty Dog)>
Re Electricity And A Saltwater Aquarium 3/15/10
I have measured the devices without the UPS and get the same readings.
You made the statement "Yes, they are considered inductors and can
create stray voltage in that regard, but if the tank water is indeed
grounded, you should read no voltage, the induced voltage should be
going to ground."
Without the use of a ground probe, how will the tank water be
grounded?
<Exactly my point, and wanted to prove this out to you. GFCI's
do not ground your tank water, they just provide protection should you
become grounded and place your hand in the water with stray voltages
present.
A ground probe will eliminate these induced/stray voltages and is also
much better for the animals in your system.>
All of my devices that are submersible do not come with 3 wire
cords.
Thanks,
<You're welcome. James (Salty Dog)>
Shawn
HLLE Related To Stray Voltage?
Ground probe 3/20/09
Hello crew and thanks for all the great advice.
<You're welcome.>
The question has been asked before regarding the value of a ground
probe.
I am in agreement with the argument that the probe completes the
circuit and the resulting flow of
current is a bigger problem from a fish and human safety perspective. I
have a 125g FOWLR with powerheads and heaters in the main tank and the
following fish: Powder Brown (A. japonicus), Tomini Tang, Flame Angel
and an Assasi Triggerfish. The Powder Brown, Flame Angel and Assai are
fine,
but the Tomini has what appears to be mild HLLE on his forehead and it
has been very slowly increasing in size for the past 6 months. Also the
behavior of the Tomini is more reclusive then active, color is good
and
seems to only like to eat New Life Spectrum pellets along with grazing
the rock and tank walls. I feed a varied diet ( New Life Spectrum
various pellet formulas, Nori, Formula II, Mysis and supplement with
Selcon). I decided to try the ground probe and I have noticed an
immediate change in behavior. The Tomini is more active and less
reclusive and now regularly eats Nori. The mild HLLE seems to be slowly
improving, but its to early to be certain. The other fish have not
changed their behavior. The equipment
in the tank is working fine and all are connected to GFIs. I plan to
experiment some more to better confirm if the ground probe addition is
the primary reason for the change in behavior. I also speculate that if
the
ground probe is a benefit then maybe the Tomini is just more sensitive
to very low electric fields relative to the other species in my tank.
The question is has there been any new information on this topic that
may help
clear up the controversy or is this still just a myth?
No myth, has been cited several times/places and your experience does
not surprise me.
If you had any stray voltage/current in your tank it would be very low
due to your GFIC protection. GFIC's will trip when a difference of
5 milliamps (.005 A) is detected. Simply said, if .25 amps are going
out to the
component, .25 better be coming back or the GFI will trip. As to new
info on HLLE, none that I'm aware of. Do some Googling, and thank
you for sharing your experience with us.>
Thanks again.
<You're welcome. James (Salty Dog)>
Fish Recommendation for a reef, grounding probe maint.,
Clown comp. 12/5/08 Second question; Is it a
problem if my grounding probe gets covered in algae? <Mmm, not
really... or at least not much> <And Neale has responded to your
FW queries... In future, please isolate/send your questions one
topic/subject at a time. Thank you, Bob Fenner>
|
Grounding Probe Info 4/23/08 Dear Crew, I was doing a
little research on grounding probes and came across this article
written by a Georgia Tech professor, and thought I'd share:
http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/GroundingProbes.html
Basically, he educates the reader on the difference between
voltage in the tank (not a problem) and current in the tank (a
problem) and concludes that the addition of a grounding probe
more often than not causes a current problem where none
previously existed (the website also contains a good discussion
about GFI outlets). Although I don't know the author and
can't vouch for his wisdom, it seemed to make sense to me.
This article was a real eye opener for me--not because I was
moments away from wasting $22 on a grounding probe, but because
every single catalog and every single e-tailer I see sells and
touts grounding probes. <I do not... and have not... all these
decades...> I assume that there are cases in which they have
some benefit, but I came away thinking, gee, this is like
"reef safe ich killer" and many of the other products I
see you guys poo-poo as worthless snake oil--it's amazing to
me that people can legally make tons of money off of hobbyist by
selling stuff that doesn't actually work or even causes harm.
Cheers, Andy <Agreed... and this is indeed a very fine
piece... and the link to this gentleman's tank project
period:
http://avdil.gtri.gatech.edu/RCM/RCM/MICHELSONAquarium.html Thank
you for sending this along. Will post/share. Bob Fenner>
Re: Grounding Probe Info... and the meaning/liability for
the term/label "reef safe" Bob, <Andy> That
guy's site is really interesting/insightful. Because I've
never used anything that claims to be "reef safe",
I've never had the opportunity to read the label or warranty
(if there is one) on "reef safe" medications as to who
bears responsibility when a hobbyist uses such a product and
his/her reef dies (or maybe nothing dies because it's just
colored water?). Something tells the manufacturer disclaims
liability. <I have said on occasion that I do wish I had the
time and/or money to hire someone in the legal biz to challenge
(i.e. sue) the many folks who make such disingenuous products...
"If only...". BobF>
Re: Grounding Probe Info Was that a subtle nudge?? ;-)
<... always> Ah, we could spend many a keystroke discussing
this topic. In some ways I am surprised it has not happened.
Lawyers tend to have more money than the average Joe =
bigger/more expensive tanks = bigger/more expensive crashes from
use of dubious products = higher $ damages. The problem with your
dream is that you need one of the following (i) a lawyer
who's been personally screwed and is willing to shoulder the
legal battle, (ii) a rich hobbyist willing to pay a lawyer by the
hour (not likely) or (iii) a pot at the end of the rainbow for a
contingency fee lawyer (i.e., a big enough class of plaintiffs
who have been harmed that a lawyer's 35-40% fee is big enough
to take the case). My guess is that the warning labels on these
products make it clear that "we cannot guarantee that
nothing will die from this. Of course it is best to treat in a
separate hospital tank, and the hobbyist assumes the risk of
adverse effects if used in the display." <Well put>
Every consumer product comes with a warranty of merchantability
(i.e., a warranty that the product does what it says it will do).
Generally, a manufacturer cannot disclaim such a warranty in a
consumer transaction. To pursue such a claim takes a lot of time
and, if you hire a lawyer, money. The court system is so
expensive and time consuming these days that it makes pursuing
these claims difficult. There is always the state's attorney
general/consumer protection division, but my experience is that
regulators are loathe to take on such matters unless there has
been a significant financial harm. <Mmm, our system of
jurisprudence/litigation is the element of being a U.S. citizen
that I "like" best/worse about America. Cheers,
BobF>
|
Grounding Probes - 4/22/07 Hi, <Hello.> I checked on
WWM under 'electricity' and did not see information on
grounding probes. <Using the Google search feature reveals many
references to them, although there are varying opinions of course. Bob
doesn't seem to be a fan.> <<Thank you Alex... I am not in
most "cases", arrangements... Better money/attention paid to
using GFCIs, polarization, better wiring period. RMF>> I am
having a difficult time on deciding whether I should use a grounding
probe. Searching the web, I find many sources saying
grounding probes are a must for aquariums. On the other hand
we have the article on why not to use them: http://avdil.gtri.gatech.edu/RCM/RCM/Aquarium/GroundingProbes.html
which makes sense to me. <This does make some good
points. The part that I don't agree with is the amount
of current they seem to think will be flowing through the ground and
the fish. While the induced voltage can build up to a pretty
high level in the tank, this is over time, and once grounded the amount
of current flowing to keep it grounded constantly will be negligible,
unless there is an actual problem with electrical components not being
properly insulated. The argument for the probe is that the
infinitesimal amount of current that would flow to the ground is not
harmful, while to sensitive species, the high potential voltage that
builds up in an ungrounded tank can be. I think of it as
background noise, which does not bother some people, and drives others
batty.> For the record, I do use GFI's on all equipment.
<Excellent. Without GFI's, there could be current
associated with a probe, but with the GFI, if there were an actual
insulation breach, it would trip.> I recently installed a controller
(Lighthouse - http://www.mcuresearch.com < http://www.mcuresearch.com/> ). The installation
instructions start off by saying make sure to use a grounding probe to
insure accurate probe readings (pH and ORP). <Well there
is your answer. Although they may not be necessary for every
tank, it sounds like you will be needing one to get your technology to
behave. Personally, I use them, ever since I measured the
voltage (46 V!) and watched the reaction of the fish when installing
the probe the first time. They 'appeared' much
calmer after the probe.> I would like a definitive answer on whether
grounding probes should be used or not. <This may always
be a controversial topic.> Thank you very much, Jill. <Welcome.
Alex>
Grounding Probes - 4/24/07 Alex, Thank you very much for your
response. I hooked up the grounding probe. My
probe readouts did not change after the addition - that is
fine. <That's good. The readings could
probably be affected for those tanks that had a significant voltage
built up. <<Mmm, voltage does not "build up".
RMF>> After initially grounding mine, it took a long time
for the voltage to return after removing the grounding
probe. It is very much dependent on the equipment installed,
probably. I suspect my old lights were part of the problem.>
Hopefully our inhabitants are happier now. <Maybe. Shouldn't
hurt anyway.> Thanks,
Jill and Aaron.
<Welcome, Alex>
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