Voltage in tank... bizarre meter readings

macphoto

macphoto

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Aug 19, 2005
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Tank is a 16g bowfront. When I placed my hand in the tank to adjust something, I noticed a slightly painful tingle on one of my fingers (which happens to have a small cut... I guess that equals less resistance). I do not have a GFCI on this outlet, but I'll be buying one of those plug-in ones from Wal-Mart that I've heard about.

Curious as to what was leaking current into the water, I pulled out my multimeter, placed the positive probe in the water, and the negative into a ground on the outlet. It displayed about 52 volts. 52 volts!?! I'm positive that it was not .52 volts, or 52 millivolts. That was somewhat alarming.

Next, I unplugged everything, at which time the meter showed about 2 - 3 volts. I then started plugging things in one by one (unplugging the last, so that only one thing at a time was plugged in). Here are the readings I got for each (subtracting out the 2 - 3 volts that was indicated when nothing was plugged in)...

Air pump: .5v
Light hood (a single strip fluorescent): 15v
HOB filter: 6v
Small internal filter: 29v
50w heater: 15v
25w heater: 32v

All those add up to almost 100 volts when plugged in individually, even though "only" about 50 volts is present when everything is plugged in. To confirm the meter was working properly, I measured an outlet directly, and it showed about 119v. These are all new (less than 6 months old) items.

Any ideas as to what all this means? I'm kinda freaked out now.

--Mike
 
50 Volts in the water means you have a ground fault.
I would find it and get the faulty equip. replaced. 50 volts in the tank water is dangerous and if you are grounded when you touch the water it could seriously injure or kill you. It takes less than 20 milliamps to send your heart into ventricular fibrillation. With wet hands and possibly bare feet you could become a conductor and that means current flow.

Mark
 
I partly agree with the above post. However, don't confuse watts with volts. A 50 V shock isn't that rough (speaking personally), we're not that conductive. However, this is definitely a serious issue that needs to be resolved ASAP before it develops into a danger. Start with the heaters and internal filter as your top suspects.

That said, avoid exposing any open wound to your aquarium, it won't hurt the tank, but you can pick up some nasty infections, fish tuberculosis among them.
 
It's amps you need to worry about! But you really shouldnt have any volts in your tank at all. I have all kids of stuff in my tank and the reading i get is ZERO. I only checked it because i keep Oscars and stray voltage can cause Hole in the head disease.
 
OK. To clarify. Macphoto said he read 50 volts. I'm curious as to whether there is a grounding conductor connected to the terminal he was measuring. If there isn't then the meter will read a float of something less than 120 volts. To make certain of the voltage present in the water measure from the water to the grounded conductor which is connected to the longer of the two slots in the wall plug. Even if there is ONLY 50 volts present, your body's resistance drops when you're wet. The tingle he felt WAS current, by the way. The easiest way for him to find the faulty device is to buy a true GFCI protected outlet, the one with the Test and Reset buttons, and plug the devices in one at a time. The one that trips the GFCI is the faulty one. All aquarium equipment should be connected to GFCI receptacles. It's only safe.

Mark
 
Now you guys have me worried. I'm renting a room in an older house and we do not even have a ground at the outlets.

Since I do not own the house and I am only renting the room I don't think there is anything I can do, buying a fancy outlet won't do much good if there is no ground to connect it to...

But hey my computers n stuff run off this too so I deal with it, although I do seem to lose computer components quite often....
 
Happychem, I never confuse watts with volts.

Mark
 
wesleydnunder said:
OK. To clarify. Macphoto said he read 50 volts. I'm curious as to whether there is a grounding conductor connected to the terminal he was measuring. If there isn't then the meter will read a float of something less than 120 volts. To make certain of the voltage present in the water measure from the water to the grounded conductor which is connected to the longer of the two slots in the wall plug.
Click to expand...
Yes, I measured from both the ground and the neutral, and both read about the same (ground and neutral are tied together at the panel, correct?).

The easiest way for him to find the faulty device is to buy a true GFCI protected outlet, the one with the Test and Reset buttons, and plug the devices in one at a time. The one that trips the GFCI is the faulty one. All aquarium equipment should be connected to GFCI receptacles. It's only safe.
Click to expand...
Thanks this is now on my list of things to do. To faciliate the testing of each device (without me having to stand barefoot on a wet floor to complete the circuit), I'll temporarily install a grounding probe.

--Mike
 
Since you don't have a 3rd conductor on your wall outlet, I'd make my own ground if I were you. Find a decent sized length of water and tie it to a good ground somewhere in your house. ....maybe a plumbing pipe, or better yet, try to find the ground rod outside and trace it back to your main circuit box ground. Anyhow, once you find ground, you can tie the 3rd prong of your multiple outlet strip to it and then you should be fine. If nothing else works, consider putting your own ground rod outside the house and using it to ground anything you feel is important. esp the aquarium equipment.

If you aren't comfortable working with electricity, I'd highly recommend bringing in a professional and letting them diagnose. It sounds like your outlet is simply bad.... but there could be bad wiring somewhere behind a wall that is not accessible.

If there is no ground running to your outlet, a GFCI outlet would be a waste of money.

(edit: I just re-read and saw that you are renting. Call your landlord and have him fix the outlet. I wouldn't mess with a grounding probe... as you have no access to a real ground. Invest in some "not cheap" surge suppressors for your electronic equipment. How old is the cord or outlet strip you are running to your tank? The voltage can't really jump into your tank unless there is a path. Do you have a metal aquarium stand? When you measured the voltage across the water, you didn't have a true ground, you were either putting the negative probe into the Phase or Neutral conductor, so I wouldn't trust the results.....other than about 50 volts is what I'd expect to see as about 1/2 the main AC voltage. It isn't safe either to bridge an AC outlet into a large tank of water. Your electrical system could be wired wrong.... as in a split phase instead of 120v on phase and 0v on neutral.)
 
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