Stray votlage

wingedfish · #1 12-27-2010, 11:12 PM

not exactly sure where a ground probe grounds (assume it's house ground) but you should check to make sure your house wireing is good. With a meter, check your wall socket blades to ground. One should be 120 or so the other should be zero. If ground in the house is broken somewhere and something in the house is shorting to ground, then ground becomes live.

Worth checking out for sure as the ground probe should not induce voltage in any way.

mike31154 · #2 12-28-2010, 01:53 AM

Here are a couple of links to what I consider some good info on grounding probes & GFCI devices. Personally I don't use a grounding probe, but do use GFCI devices for all my tank equipment, more than one for redundancy.

http://angel-strike.com/aquarium/GFI...alDetails.html

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

I also agree with some of the points wingedfish brought up. It sounds like wherever you had your grounding probe attached, there is a problem. If it was a ground on a wall receptacle, it wouldn't be a bad idea to get hold of one of those receptacle testers available at most reno centers these days. This handy little device will tell you right away if one of your receptacles is improperly wired or has a bad/missing ground.

Ian · #3 12-28-2010, 05:20 PM

Yeah gotta get a tester today and do some searching....

sphelps · #4 12-28-2010, 07:17 PM

The problem wasn't really the grounding probe it's functioning properly. Using a grounding probe will promote stray voltage. Typically most pumps will produce a small amount of stray voltage but it will stay localized at the pump unless a ground is introduced giving something for the current to flow towards. This is partially why I don't believe grounding probes are a good thing, they simply promote current flow through your tank which is the dangerous part and if combined with a GFCI it can cause it to trip and cut power when a problem doesn't really exist. Use a GFCI for safety but ditch the grounding probe, it's not helping you.

mike31154 · #5 12-28-2010, 09:18 PM

In the first post, the OP said he felt a tingle until he removed the grounding probe. If current was flowing from a piece of faulty equipment through the probe to ground, he shouldn't be feeling a tingle. This makes me suspect that he may have a faulty receptacle (or wherever the grounding probe was 'grounded') and that this is actually introducing a voltage potential into the tank and when he put his hand in the water, becomes the return path. This is why I suggested he investigate his house wiring.

But again, yes, I don't personally use grounding probes because their presence can actually hide or mask a problem all the while giving you a warm and fuzzy because you have one installed. Power can be a funny character, lots of gremlins in the wiring. GFCI is the way to go for your personal safety.

sweet ride · #6 12-28-2010, 09:39 PM

tagging along....

..... does anyone have a link on how to check stray voltage in the aquarium?

mike31154 · #7 12-28-2010, 10:03 PM

Most folks simply use a multimeter set to the AC volt scale. One test probe into the water, the other to your ground connection. The voltage potential you get will vary depending on the type of equipment you use and in what shape it is. Any kind of fluorescent lights will most certainly induce some voltage potential into the water, depending on how far above the surface the lamps are mounted. Low levels of AC voltage are generally nothing to be concerned about. However, when the potential gets to a certain point, current will flow through whatever it can, the path of least resistance. If you don't have a grounding probe, the potential is just that, potential only until a path to a lower potential is found or introduced. That could be you, a grounding probe or any number of other things.

If you take lightning as an example, that's a massive, instant current flow through the air, sometimes from cloud to cloud and sometimes from the sky to earth. The voltage potential in a cloud or certain area of the sky is always present, essentially harmless. One of two things will generally cause the lightning to occur. Either voltage potential difference between sky and earth becomes so high that it overcomes the resistance of the air, crack. Or the air gap resistance is lowered somehow, rain maybe, so the current can flow more easily, crack.

So if you're standing barefoot on a wet floor or your skin is wet, chances are you will provide a path of lower resistance for any voltage potential in your tank. You may also get tingled as I have, by touching a flourescent T5 reflector with your arm while your hand is in the water. I've now grounded all my retrofit T5 single reflectors to minimize any difference in voltage potential between them and the water. So theoretically if the reflectors are grounded and the water is grounded, I shouldn't get zapped. But there are a couple of heaters and a powerhead in the water too. If they're breaking down, I could still get buzzed. Hopefully my GFCI devices will cut power to those items before there's a chance of serious injury.

Seafan · #8 12-28-2010, 11:57 PM

Quote:

Originally Posted by mike31154

But again, yes, I don't personally use grounding probes because their presence can actually hide or mask a problem all the while giving you a warm and fuzzy because you have one installed. Power can be a funny character, lots of gremlins in the wiring. GFCI is the way to go for your personal safety.

I'm confused by this. I had a small powerhead that was causing me to get a small shock every time I put my hands in the water, it was plugged into a gfci as was everything else in the tank, yet the gfci was not tripping. At the time I did not know which device was causing the shock. We picked up a grounding probe and it instantly tripped the circuit. Had to use a process of elimination to determine the faulty device. So until the grounding probe was in the tank the gfci wasn't ever going to trip to warn of an issue or possible harm. So my question is how do you know when a gfci is going to function properly to possibly save your life? For now I will trust my probe.

mike31154 · #9 12-29-2010, 01:38 AM

Quote:

Originally Posted by Seafan

I'm confused by this. I had a small powerhead that was causing me to get a small shock every time I put my hands in the water, it was plugged into a gfci as was everything else in the tank, yet the gfci was not tripping. At the time I did not know which device was causing the shock. We picked up a grounding probe and it instantly tripped the circuit. Had to use a process of elimination to determine the faulty device. So until the grounding probe was in the tank the gfci wasn't ever going to trip to warn of an issue or possible harm. So my question is how do you know when a gfci is going to function properly to possibly save your life? For now I will trust my probe.

There are no absolute foolproof guarantees, even GFCI devices can fail or be faulty and everyone's wiring situation is a little different. You say you received a small shock, perhaps it was insufficient to trip the device. Not really sure why or how in your situation, adding the grounding probe suddenly caused the GFCI to trip. They are sensitive devices designed to operate on a very low amperage current differential between line and neutral.

I've had the GFCI trip on occasion simply from plugging in a small powerhead or air pump. Once the device is plugged in and I reset the GFCI, it's fine. I also have a T5HO set up on a digital timer power bar consistently tripping my GFCI. I have two of these set ups that are identical, same power bar, same ballast, same lamps. One trips the GFCI, the other doesn't. I simply don't use the set that trips the device any longer even though there's no indication of a safety issue.

sphelps · #10 12-29-2010, 02:18 PM

Quote:

Originally Posted by mike31154

In the first post, the OP said he felt a tingle until he removed the grounding probe. If current was flowing from a piece of faulty equipment through the probe to ground, he shouldn't be feeling a tingle. This makes me suspect that he may have a faulty receptacle (or wherever the grounding probe was 'grounded') and that this is actually introducing a voltage potential into the tank and when he put his hand in the water, becomes the return path. This is why I suggested he investigate his house wiring.

But again, yes, I don't personally use grounding probes because their presence can actually hide or mask a problem all the while giving you a warm and fuzzy because you have one installed. Power can be a funny character, lots of gremlins in the wiring. GFCI is the way to go for your personal safety.

The ground probe cannot be the source, it's only connected to the ground and if the receptacle didn't have a proper ground then removing or adding the probe would not make a difference. I see no way how a receptacle could be faulty in such a way that a ground probe would add voltage. The stray voltage is from the pump since unplugging the pump eliminates the voltage (also in the OP). Removing the ground probe simply prevents the flow of current, voltage can be created through induction in many ways from pumps and lights but it does not mean the equipment is faulty. Adding a ground probe creates a path for current to flow, typically the ground probe is a strong ground and a person won't feel any current because the ground probe is a much stronger ground but electricity takes the shortest easiest path so a poor ground is more likely the issue relating to the stray voltage but a better ground isn't the solution IMO.

Remove the ground probe, use a multimeter to measure the voltage between the tank water and removed ground probe. If you measure a voltage then the ground probe is functioning properly. The tank is obviously not grounded so voltage cannot flow from the ground probe to the tank, it must be the other way.

A GFCI is the best way to go, a ground probe won't really protect you, this example clearly tells you that. If the current was large enough to cause damage it still would go through you over the ground probe just as the small amount did.