Stray Voltage

[FleeVT]

I felt a slight tingle on an open wound when I put my hand into my mixing trash can today. I pulled out my voltmeter and read 4 Volts.

So, I figured, while I had my meter out, I would test my tank. That registered 5.8 Volts! :eek1: I've never felt any "tingles" on wounds with my hands in my tank before, but now I'm a little freaked. It seems that every appliance I have leaks a small amount, but the biggest contributor are my VHOs. I know there are electromagnetic properties at work with my fluorescents, but my results have left me utterly confused. Could anyone chime in with some sound reasoning?

I turned everything off then turned each item individually to see what there impact was. Here are the results:
Mag 5 return ~ 0.2 volts
Mag 7 skimmer ~ 0.2 volts
Rio phosban reactor ~ 0.2 volts
Koralia 3 PH ~ 0.2 volts
Koralia 3 PH ~ 0.2 volts
PC Actinics ~ 5.2 volts
VHOs ~ Fired up at 7 volts, then steady at 5.2 volts

The following is what really confused me:
Both Actinics and VHOs on with nothing else is 7.2 volts.
As I started turning other things on, the stray voltage went down, to eventually about 5.8 with everything on.

I plan on picking up a grounding probe ASAP. Any other advice? BTW, to test I set my meter to VAC and inserted red probe into sump and black probe into ground on a wall socket. Any issues with my test methods?

I plan on picking up a grounding probe ASAP. Is there anything else I should do? Troubleshoot the lights? How bad is it?

 

[FleeVT]

Bump.

 

[ReefWreak]

Yea I've been meaning to get a grounding probe, and I've tried to measure my tank a few times, but I'm not familiar with my multimeter, and even then I don't know how accuate it is.

Lee, if you ever want to do some more tests for some frags, I'd love for you to come by for a bit when I get back from school... I've been shocked before, but I could never figure out if it was me just feeling a sensation and then freaking out about it, or if it really was a shock.. hmmm...

 

[jeffbrig]

Anywhere that you have current running down a line, you create an electric field (as well as a magnetic field). These fields can induce a current in another conductor that lies within the field. Ever heard of someone stealing power by running wire parallel to the power company's transmission lines (don't try this at home, kids)? Same basic principles/physics.

Now, with various sources of electrical currents all around the tank, it is subject to lots of relatively weak electrical fields. The total electric field is the sum of the individual ones. But, direction matters. Two fields of opposite polarity can offset one another. Depending on the orientation of the wires carrying the various currents, the resulting fields are added or subtracted.

This 'might' explain why you're seeing varied results. The higher voltage while the VHOs are lighting is expected, since it corresponds to the higher current surge while the bulbs are firing. As you turn on other items, their fields may be partially cancelling that field, reducing its overall magnitude.

That said, I would be stunned if these relatively weak fields were capable of generating 7 volts of AC in the tank. Usually the bigger AC voltages are caused by submerged equipment that's not sealed well. Just to be sure, were you measuring DC or AC? Are you sure of the range the meter was set to while you were measuring? I would expect something on the order of mV rather than Volts if we're talking about induced voltages.

My 2¢

-Jeff

 

[Young Frankenstein]

Get the ground probe, it may be leakage due to wet conditions or it may be magnetic resonance creating a field. Most likely the probe will eliminate the problem.