Danger! High Voltage!

Okay. I finally had a chance to check, and the voltage between grounds on different receptacles is 0.0v.

 

Hmm. Seems it's from the tank then. Try unplugging everything that's involved with the tank and check voltage. It should read zero. Plug in items one at a time, checking voltage with each addition, until the culprit is found.

 

Okay, I unplugged everything & tested, and the 36g was 2.2v, and the 20g was at 1.5v. I tested each appliance one-by-one and they are all causing a voltage reading. The lowest, a Rio pump at 3.9v, and the highest is a heater at 11.0v. I can provide the breakdowns for each appliance if youd like.

 

A grounding probe would be helpful, but most importantly, you should consider replacing the items that are leaking voltage into the water.

I'd start with the probe, and see how that changes things.

I'm a bit baffled. If you unplug everything associated with the tank, and STILL have voltage in it--I don't know what to say.

Does your main electrical panel have a main? (a means to kill power to the entire dwelling?) If so, consider killing the panel, and checking again. If you still have voltage in the tank, your meter is faulty or there's user error somewhere.

Sorry I can't be of more help.

 

If your tank has 40 stray volts, you would be able to feel it with your hand. All tanks have stray voltage, if you can't feel it and all of your stuff is fine, your probably just wasting your time looking for bad equipment. Almost all electrical omits stray voltage. The magnetic fields, of magfloats, koralias, etc, will all through off the voltmeter depending how close you are to each device.

Reefsparky, can you put together a quick "how-to test for stray voltage" reply? I'd like to start a thread asking everyone to test their tanks and compare the findings. I have a feeling that almost everyone's tanks are going to have some stray voltage.

 

As for the "how to test," reply; here ya go. . .

First off, there are analog and digital voltmeters, and almost no two are alike. If the probes are reversed on a digital VM, the reading will simply be preceded with a minus sign, but will still be accurate. If it's an analog meter with a swing-arm, then polarity in placement will either give a correct reading, or bury the arm hard into zero. If you have an analog meter, to be safe, just take a reading both ways. (switch the probes).

1. Place one probe in your tank water--it doesn't matter if it's the sump or the display tank, but do your best to test some distance from pumps, powerheads, or other devices that move water.
2. Place the other probe to ground (the bottom center plug of a standard receptacle).
3. Read the voltmeter.

If you find voltage, shut off everything--better yet--kill the breaker serving the tank, and test again (the ground still works with the breaker in the off position). If you still detect voltage, then you are introducing voltage into the tank from a ground fault that exists somewhere else in your dwelling. If this is the case, you might consider contacting an electrician to find out why voltage exists on your grounding conductor--this should not be the case.

Hope this helps.

 

Well, thanks a lot for trying. I'm not sure if it has a main. The times I've used it was just to kill power to individual circuits. I'll check when I get home. This just seems really weird to me that both tanks would exhibit this much stray voltage, and every single item I'm using in it has been contributing. The devices in the tank are between 1 and 5 years old, but they're all in good condition. (As far as I can tell by a visual inspection..) I'll kill the power to everything in the house & take another reading. If that's still showing some voltage, then I guess I'll have to find a new meter. I think I saw one at Harbor Freight for a couple of bucks. May be worth a try just to compare to the meter I have now. If they read the same I'll try using a ground probe & see if that helps. *sigh* Well my tank inhabitants seem to be doing well. I haven't seen any behavior or physical changes that would lead me to suspect a problem with stray voltage.

Thanks for all your time & effort helping me with this problem ReefSparky. I appreciate it!!

 

Good luck!

 

I'm pretty electrically ignorant, but wouldn't that much stray voltage trip Ravenmind's GFI circuit? I've never checked for stray voltage but pretty much depend on GFIs and grounding plugs to keep that in line. Am I naive? I have a pH probe which reads all over the place if I use house current but works fine with a 9 volt. Stray current? - Paul

 

Howdy piezopaul. It's pretty ironic that you are self proclaimed "electrically ignorant" yet your name suggests otherwise.

Anyways, a GFI monitors current coming in, and current going out. It compares the two figures and trips the circuit if the disparity exceeds 4-6mA. Thing is--if a device is leaking current into its surroundings (like water for instance) this will not be detected by the GFCI since the current is not travelling through the "out" wire. Rather, it's simply subtracted off the incoming.

As a result, current leakage will not trip a GFCI.