Q for Randy or Electrician

[sowellj]

Hey Randy,

I have some stray voltage getting into my tank, primarily from my dart return pump. When I first noticed this, I replaced the pump with a new one but the problem came back. Very strange I know as it is hard to see how voltage could leak given the design of the pump, not to mention two different pumps having the same problem. Yet in both cases, when the pump is unplugged the problem is mostly gone. My metric is any tingling sensation I get when I put my hands in the tank w/out shoes on. Until I get a hand on what is going on ... my question is this: Fish and corals will not feel the voltage as it stands now ... just like I don't feel it when I have rubber shoes on, correct? The tank is just more or less sitting at a potential. Not super safe, I know. It is strange the GFIs don't trip. Anyway, thanks a bunch.

[Randy Holmes-Farley]

Is the tank water grounded to allow the GFCI to trip without you in the circuit?

[sowellj]

No it is an old house ... actually I am converting an old school cafeteria. Our panel is the old two wire. I wired the GFIs w/no ground as grounding wire doesn't exist on our panel. While not ideal, I read and asked and the GFIs will still function w/out grounding wire. So, the tank just sits at a potential, and, until a path is created, current does not flow. I chatted w/an electrician friend about it and he verifed what I thought. That is, the inhabitants would be unaware of the voltage leak until a pathway was created. Safe for them ... not so safe for me.

[Randy Holmes-Farley]

I wired the GFIs w/no ground as grounding wire doesn't exist on our panel. While not ideal, I read and asked and the GFIs will still function w/out grounding wire.

They do, but to trigger, they need a ground of some sort for the current to enter, and you may be providing it when you put in your hand. Perhaps that to date has not been enough to trigger the GFCI, but it might become so with a better ground.

I'd avoid those pumps, at least until the water is grounded, and try to make a ground myself by attaching a wire to a metal water pipe and sending it to a ground in the water. You may find the pump trips the GFCI in that setting.

[sowellj]

Thanks for the help Randy. I don't know what to make of the pumps. I took one apart, and I cannot figure out how voltage is leaking. From what I can tell the shaft is ceramic ... so should not conduct. The electrical feed to the pump is metal, but is isolated by plastic. I cannot find any sort of 'salt bridge' ... who knows.

[Randy Holmes-Farley]

How close was your hand to the pump when you felt something?

Maybe it was an induced current from the moving magnets.

[sowellj]

Also, as I understand it and from chatting w/my electrician friend, if I do ground the tank right now, and assuming the GFI did not trip at that point, then the fish/coral could potentially feel the current then as it would be flowing.

[Randy Holmes-Farley]

If current is flowing, wouldn't the GFCI trip unless it was defective?

Maybe try it in a different GFCI outlet, if it didn't trip, just to be more cautious.

[dan223]

Originally Posted by Randy Holmes-Farley

Maybe it was an induced current from the moving magnets.

Thats what I would think, coming off the coil.

[sowellj]

I was thinking along the lines of induced current as well. Checked the vortechs just to be sure. Also, during a feed cycle (pump is off) the voltage is still there, yet, when you physically unplug the pump, no voltage. So, I am not convinced it is induced current.

Just to be sure, do you guys concur w/the electrician I chatted in with in that the fish/corals do not feel the voltage/current since the tank is just sitting at a potential, but without an outlet for the current to flow. Basically, the same priniciple that I don't feel anything if I wear shoes and put my hand in the tank. Thanks guys.

On an aside, Randy you aren't involved w/any of lysosomal storage disorder work Genzyme does are you ... I seem to recall you being in the DMPK group.

[bertoni]

I agree that it's unlikely that the fish will suffer much from a potential, but I'd rather have the fish suffer than me die or my house burn down. Stray currents can be tracked down to bad equipment, for the most part. Induced current are unlikely to be an issue, IMO.

GFIs and sground probe make the tank a lot safer, IMO, and I always use them.

[HighlandReefer]

I have read discussions recommending the use of ground arc circuit breakers in conjunction with GFCI outlets to get the most safety for a reef system. I would think you would want to run proper wiring to your system.

[HighlandReefer]

FWIW, I don't want to sound too harsh, but in my local club we have had two house fires do to reef aquarium fires. One was in a new house with new wiring on a GFCI & the other was in an old two wire house. Both were caused by arcing of light fixtures and could have been prevented using a Ground Arc Fault Circuit Breaker. That is why they are requiring them by code in all new homes in bedrooms and probably will soon require them on all circuits that they can be installed on. Simply put, use Ground ARC Fault to prevent fires and use GFCI to prevent electrocution.

[Boomer]

So, I am not convinced it is induced current

Most of this so called induced voltage is not real voltage and is picked up by VOM' s from picking up electromagnetic fields produced by equipment. Any piece of equipment will do this. If you go buy a 10 gal tank, a new PH and heater and check it you will find voltage, usually no more than a 40 V. If you now ground the water it will show zero volts. It is very dangerous to ground water without a GFCI. When you really have a voltage leak it will be quite high, say greater than 80 V. There has been much written on this subject by electrical engineers who have studied this so called induced voltage in tanks.

Lots of web space has been devoted to the measurement of voltage in aquariums... most of which is of no value.

Technical Considerations Regarding Static Potentials
http://angel-strike.com/aquarium/GFI...alDetails.html

Grounding probes
http://angel-strike.com/aquarium/GroundingProbes.html



do you guys concur w/the electrician I chatted in with in that the fish/corals do not feel the voltage/current since the tank is just sitting at a potential, but without an outlet for the current to flow. Basically, the same principle that I don't feel anything if I wear shoes and put my hand in the tank.

Yes

[HighlandReefer]

Boomer,



How's the vacation going?

[Boomer]

It is OK Cliff but has been very wet and windy

[HighlandReefer]

I'll send some of our snow.

[HighlandReefer]

One thing you have to be careful with when grounding the electrical to the water supply in old housing is that in some cases the exterior water supply may have been replaced with pastic at one time or in other cases the pipe may have leaked and eroded soil from around the pipe for quite a a long run, which reduces the ground effect of water supplies.

I've seen cases where they cut the water supply just outside the house and replaced it with plastic at that point.

[HighlandReefer]

I was curious myself regarding the GFCI and if grounding was needed. I was under the impression that grounding wasn't needed.

Here is a link discussing this issue:

http://www.naturalhandyman.com/qa/qagfci.html

From this thread:

"Dear MG,

Sorry about the confusion. I went and reread the passage, and I became confused too. My head was turning two ways at once, and the words followed.

Because portable GFCIs are generally used in hazardous situations... most are used by contractors and tradespeople on work sites... they should be used in grounded situations. Since GFCIs can and do fail, using a metal framed portable saw in the grass and compounding the danger by not providing a ground for the tool is dangerous!

However, portable GFCIs do not need a ground to function, since they are designed the same as stationary ones. In fact, one reason for using a GFCI is to protect a person in case the ground is disconnected!

Remember that GFCIs protect from extreme shock, but slight shocks can occur before the GFCI disconnects the power! Therefore people who might be adversely affected by very slight shocks (people with critical livesaving devices such as pacemakers, for example) should be even more cautious!

I am unsure what the humming noise is, but it can only be a malfunction, even if the unit appears to be working OK. Best to err on the side of caution with electricity. Even though the cause of the noise is unknown, I would suggest replacing the GFCI.

Thanks a lot for allowing me to clarify my remarks."
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You will want to read the entire thread as there are other complications possible.

[bertoni]

The GFCI works by detecting current mismatch, and so some extra path to ground (or a large capacitance) must be around for the device to trip. There are lots of paths to ground that can exist in houses, though. A damp concrete floor can be enough, apparently, for example.

[Randy Holmes-Farley]

On an aside, Randy you aren't involved w/any of lysosomal storage disorder work Genzyme does are you ... I seem to recall you being in the DMPK group.

No, neither. I lead the Therapeutic Polymer and Biomaterial portfolio of research programs.

Existing products of ours that are considered Therapeutic Polymers and Biomaterials are Renagel, Renvela, and Cholestagel/Welchol, Synvisc, and Seprafilm.

www.renagel.com
www.renvela.com
www.cholestagel.com
www.synvisc.com
www.seprafilm.com