[benealing]

Thought I would post this as I am not certain why it occurred.

In my 55 gallon tank, I have two heaters a 300W and a 200W. This tank is in the basement which stays about 64-66 degrees and it takes a lot to keep the tank warmed.

I was changing the water this weekend and when I put my hand in the water I felt a mild burning sensation on a cut on my index finger. I didn't think too much of it and finished the water change. After I finished the other two tanks, I realized I did not get the same feeling in that finger and I wondered why.

I went back to the tank and still felt the mild tingling. It did not happen to any other finger, just the one with the cut. I thought it might be an electric current and so I unplugged everything. I plugged things in one at a time until I determined it was the heaters.

There was a current in the tank when either heater was plugged in individually or both together. I took the heaters out and inspected them, but found no visible damage. The cords were wrapped around each other so I isolated them and then plugged each heater into a different outlet which solved the problem.

I know I should not have been sticking my hand in the water with a current flowing, but I am a dumb man and did it anyway.

My question is, why did this happen? Anyone with an electrical background provide a reason? Initially both heaters were plugged into a three outlet extension cord. Afterwards, one was in the extension cord in one outlet, the other was in a surge protector in a different outlet on a different circuit.

Thanks,
Ben

 

[PlantedRich]

I have a background in power gen as related to telephone line work. That is not going to get us far on a real answer but only that there are lots of "phantom" currents and you have found yet another way to generate them. The saving grace in this situation is that the power (110AC) is not huge and the distance involved is not long as in miles. When you have lines running a few miles under a 7600 Volt line, the induced voltage can kill a guy but not when it is 110 running for a few feet.
Not that the 110 is not dangerous stuff. It is more likely to kill you than the 7600 due to the 7600 may burn an arm or leg off while the 110 can cause heart failures. But the induced current is not likely to be very large in your setup. Just enough to notice it on the cut where things are tender but not on a normal finger?

I've noticed this at times but, in general, I don't worry much about it. Like you it is a weird feeling that does cause wonder but then not too much worry.

 

[benealing]

Thanks for the insight. The feeling was much more like citrus on a cut than electric current and I could feel nothing on unbroken skin. The intensity was far greater at the surface than under the water.

Ben

 

[Kubla]

Stray current like this can be harmful to fish. I know it can be an issue in koi ponds. Fish can end up with crooked spines and other issues.

 

[benealing]

Fortunately in this particular tank, there are just plants. It did make me think if the stray current would have an impact on plant growth. PhD thesis project anyone?

Ben

 

[PlantedRich]

Sorry! No time to take that project until I figure how much the RF from my cell phone has drained my memory........

 

[Linwood]

This is a frequently debated subject but I'll offer my two cents.

First, anytime significant amounts of water are in contact with 110v, it is best to have the outlet protected by a GFCI breaker or outlet. The outlets are very cheap and easy to install, the breakers not quite so easy but not hard. They can literally save your life and should always be used for outdoor circuits, near pools, bathrooms, and in my opinion largish aquariums (the kind that could for example spill a lot of water onto a floor).

Now that said, most aquariums where you can feel such voltages tend to be a type of static charge, coming from friction of flowing water, plastics, glass. It can also be induction for flowing current in a heater, I guess. Basically anytime you have a moving electrical field (and AC is by definition moving) you can induce current flows in nearby conductive objects. In a transformer, for example, there is no actual connection between the incoming wires and the outgoing wires, it is all magnetic/electrical fields. Moving between outlets can change which phase of the AC you are on, conceivably (if they go to different sides in your breaker panel), and affect it (e.g. now instead of both going plus at the same time, one is going minus when the other goes plus -- speculation here).

You COULD have an actual voltage leak, but the chances of two heaters having such a insulation failure, of about the same amount, at the same time, seem pretty slim. So I doubt you are actually seeing 110v leaking by direct connection into the water. Though frankly I do not see how heaters contribute to a static charge (unless these are in-line with a water flow?)

The static charges are a lot like touching a doorknob after walking across the room, i.e. nothing is happening really until you touch it, then you feel the flow. Hence "static" . Static buildup in a tank is not necessarily bad, and is often something you cannot prevent. People who recommend ground rods in the tank to let this flow off can actually make this worse -- you stop feeling it, but now you have flowing current through the water instead of just static charge. It's current FLOW not charge that can harm fish. There are circumstances where ground rods may be appropriate, but I would not start there.

If you have a good ohm meter, you can try this. Unplug the heater. Put one probe in the water and fasten it there (clothes pin or something). Put the other probe beside the heater - see what you get as a reading. Now go move that second probe to the AC plug on each connector in turn. Compare readings. There should be a dramatically higher reading on the heater than in the water, in fact the heater may read as an open connection, which is good. If you get nearly the same, that is bad and your heater really does appear to have a breakdown of insulation. Be sure the heater's cord is dry and not wet throughout its length and so conducting (a drip loop is always a good idea in AC cords, so water running down them reaches a low point and runs off before going to the outlet). I'd bet heavily the heater is not leaking through the insulation, at most it is causing some inductive flow that is likely harmless, though all physics aside, I'd probably swap to a different heater type just so I would not worry about it.

 

[PlantedRich]

Reason I fell back to thinking "phantom" when I had the bite was that the GFCI did not pick it up as a leak. I use the small plug-in type as they are so easy to move around and take no install. They can get a bit too touchy and shut things down when I really would like them to continue to work but there do give enough added safety that I use them. I now mostly plug lights and heaters that I've learned get wet more often and not plug filters into the GFCI. I'm here quite a bit and can spot trouble soon but if I were out when things got shut down, I would rather it not be the filters. Another one of those places where we each need to look at what we have, what might happen and then do some thinking about how to avoid the worst cases. I like the added safety if I drop a light or a heater goes bad but I'm willing to go with the filters not on GFCI to avoid the unneeded hazard of them being off for a long term due to an over sensitive GFCI.

 

[Linwood]

It could be an induced voltage, I just do not know anything about how that works in water with small (and short) flows of current. But I suspect if so, given how short a run it is, it is not a dangerous one?

I've had filters trip GFCI's also, mostly if I turn off or on more than one filter at a time, e.g. on a power strip (or due to a power failure). My GUESS is that the rotating magnets continue to move a bit in with the inertia of the water flow, and for a fraction of a second are acting as small generators and produce enough current to affect the GFCI's current leak circuit and trip. It does give me some concern after power failures, but it happens infrequently enough I take the chance of that, rather than the chance of a bigger problem. In my case the outlets all feed from under-floor (in concrete) outlets and in the event of a big leak, they are going to be under water. Last thing I want is someone walking over to clean it up and stepping in an energized puddle just as they touch something metal around the tank.

 

[Seetide]

If your worried you can always run a grounding probe to the tank, I used one on every saltwater tank I set up. Obviously saltwater is much more conductive, and the tingling you experienced on an open cut is definitely from stray voltage. Its possible since planted tanks are receiving ferts with small concentrations of metals, this increases conductivity more than in a standard freshwater tank. The probes are really inexpensive or you can DIY since most of the available ones are coated in titanium to be saltwater resistant.

 

[Linwood]

The problem with a ground probe is while it may remove the feel of the current for the human, if the buildup is basically a static charge, it will turn the charge into a constant flow of current through the water, which reportedly is bad for fish. I emphasize reportedly as I have no clue personally how much difference it makes, in open water and rivers there are also sorts of current flows (of the electrical kind) just in nature, much less when high voltage power lines are nearby.

Picture the bird sitting on a bare, high-voltage power line -- the charge itself does no harm. Give the bird a path to ground, however, like then pecking at part of the poles grounded surface, and you end up with fried bird.

There's a pile of debate in various forums how much ground probes help or hurt. My own feeling is above, but it is more feeling and opinion than science. Unfortunately I have yet to find any good science addressing the subject.

From a human safety perspective, I do think, however, that GFCI breakers are without question appropriate and life savers. You can still feel static and induced voltages but those are not going to hurt you. (And yes, before someone jumps in, it is possible to still get hit with AC, if you have a device that has both hot and neutral exposed without having any ground in the tank -- but that's almost sabotage, not accident).

 

[benealing]

I have installed GFCI outlets on DIY projects, but never replaced on in my house. It the process identical? Shut off power at the breaker, remove old outlet, correctly wire new outlet, turn power back on? Is there anything else to it?

Ben

 

[Linwood]

I have installed GFCI outlets on DIY projects, but never replaced on in my house. It the process identical? Shut off power at the breaker, remove old outlet, correctly wire new outlet, turn power back on? Is there anything else to it?

Ben

Provided you have 3 wires (load, neutral, and separate ground) in the house wiring, that is it. You can protect downstream outlets as well as you can daisy chain them off the protected side of the outlet (just be sure you wire the right one to the feed from the panel).

The GFCI outlet needs to be, itself, out of possible water though, so these are not suitable for mounting in floor outlets, or anywhere water may spray or rise to cover the outlet, as they only turn off power to the wires coming out of the outlet, not coming in. For those outlets either get further in the chain toward the panel, or use a breaker panel GFCI.

Breakers in the panels are similarly easy but to be safe require turning off the entire panel power, which is inconvenient for some; it also requires running the neutral to a different place (the breaker instead of the neutral bar) which may or may not reach. I'm a fan of breakers personally because it is a single place to go check whenever you loose power, but they are much more expensive (like $25 vs $5), especially if it is a bit over the DIY rating you feel you have.

 

[benealing]

Thanks for that information. Definitely above my pay grade to work at the breaker box. Is there an easy way to trace the chain of outlets to find out where to place the GFCI upstream?

 

[Linwood]

Thanks for that information. Definitely above my pay grade to work at the breaker box. Is there an easy way to trace the chain of outlets to find out where to place the GFCI upstream?

None that I have ever found that is reliable. There are tone kits that purport to do so, but I have never had good luck, and even then it is hard to tell if they are up or downstream. The only thing I've ever managed to do is find all the things on a breaker (e.g. which go off when you turn it off), look at it physically and guess how they ran the wires, then open up the one nearest the breaker, disconnect it, turn the power back on and see if I was right.

I just had an issue with stray neutral current tripping a GFCI breaker, and traced it to a wire going off one of my outlets, and no matter where we looked could not find where it went. I ended up leaving it disconnected, figuring one day we would find a dead outlet -- so far have not, it just seemed to go off into space.

Electricians wiring houses sometimes get creative. Or drunk.

 

[benealing]

Electricians wiring houses sometimes get creative. Or drunk.

This made me laugh

I think I will just install individual GFCI outlets where I need them just to be sure.

This has been tremendously helpful and potentially saved my owner, if not other people from dangerous situations with electricity.

Thanks again,
Ben

 

[Linwood]

I think I will just install individual GFCI outlets where I need them just to be sure.

If you mean you may daisy chain more than one, I have heard that is a bad idea. I do not know why, I do not know for sure, but I would find someone who knows for sure before putting more than one in a daisy chain. Now you can put more than one where each is fed from the unprotected side of the prior outlet, that will work fine, for sure.

And maybe feeding from the protected side is OK. But check, because I know I've been told otherwise, just not sure if that advice is reliable.

 

[PlantedRich]

Sometimes we miss a bit on the prices that are handy for many of our shopping trips? I don't find GFCI outlets under $15 for most of my places I shop and then there is always the question of how to wire one. That leaves me recommending a bit different way for lots of people who do want to add the protection. How concerned we are is often easy to see when we look at a few videos on the tube! When they are showing how easy it is, you can sometimes see they have little sense of being safe when they show all the electrical laying on the floor with no drip loops or covers to keep water out. But then those folks are not the ones this discussion is for anyway.
If you are looking for a fairly cheap item that almost anybody can use that can save you or your kids life, I suggest this:

Shop Shock Buster 2-ft 15-Volt 3-Outlet 12-Gauge Yellow / Black Outdoor Extension Cord with GFCI Circuit at Lowes.com

Instead of the $15 I find paying for GFCI outlets, this will cost you $25 but all you have to do is plug it in and then plug all your tank equipment into the three outlets. Is your family worth $15-25 ?

 

[GraphicGr8s]

This made me laugh

I think I will just install individual GFCI outlets where I need them just to be sure.

This has been tremendously helpful and potentially saved my owner, if not other people from dangerous situations with electricity.

Thanks again,
Ben

One GFI per circuit. In general the outlet closest to the panel is the first one and if you put your GFI there it should protect the rest. Simple check is to trip the GFI after install and see if all outlets go dead. Any that remain live will of course be ahead of the GFI outlet.

Wiring them is not difficult at all. Most today just require pushing the wires into holes in the back of the outlet.

You don't want to use GFI's on all circuits though. Some motors and small appliances will constantly give nuisance trips. (Also why you only put one GFI per circuit)