Stray Voltage?

[Baldy]

im not exactly sure how electric devices leak voltage into an aquarium. I like using the water analogy, it makes a bit more sense to me. measuring voltage is just measuring a difference between 2 points, just like measuring pressure inside a pipe. its a comparison between the pressure inside the pipe and outside the pipe. adding a ground probe is like drilling a hole in the pipe. if it is static electricity that is giving you the voltage, the voltage will equalize and there will be no current after it does as there is no further source of voltage. but if its a powerhead that is leaking voltage into the tank, going back to the water analogy, its like having a pump applying the pressure inside the pipe. when you drill the hole water will flow out of the hole constantly until the pump is shut off.

It would be difficult to answer whether or not it would be enough current on the ground probe to trip a GFCI. but if it doesnt to begin with, if a heater or powerhead fails and leaks more voltage into the tank, it could in the future. As far as im concerned, a ground probe is a band aid for an underlying problem.

[Reef Pilot]

I used to have a T8 canopy light fixture sitting on top of my refugium/QT that was producing stray voltage in the tank. I don't know exactly how that was happening, as the canopy was not in contact with the water, just sitting on top of the glass tank. It was plastic, too. But when I turned it off the stray voltage would disappear, so it was definitely happening.

I also had a few different pumps that would produce stray voltage, so now just have ground probes in everything. No more stray voltage.

[banditpowdercoat]

Stray voltage can be introduced my leaking through the wire's insulation, or by Induction. Ballast have a huge magnetic field. And properties in your tank, can react and make electricity by a induced magnetic field into the metals in your tank.

I've been shocked off metal structures that were beside Flourescent lights before. The Ballast was inducing about 90v into the metal. Not much current, enough to just feel a little tingle, but it was there. Ground probes are good.
That's also a reason we ground copper water pipes in your house. Electricity running in wires beside the pipes, can induce voltages into the pipes.

[beefORchicken]

I assume you are testing wrt ground (one leas connected to an outlet ground)
there is always noise from the electromagnets in motors and you should see it drop as you test farther away from pumps.
35V sounds like broken insulation though, is there any current when you test?

[Baldy]

Originally Posted by banditpowdercoat

Stray voltage can be introduced my leaking through the wire's insulation, or by Induction. Ballast have a huge magnetic field. And properties in your tank, can react and make electricity by a induced magnetic field into the metals in your tank.

I've been shocked off metal structures that were beside Flourescent lights before. The Ballast was inducing about 90v into the metal. Not much current, enough to just feel a little tingle, but it was there. Ground probes are good.
That's also a reason we ground copper water pipes in your house. Electricity running in wires beside the pipes, can induce voltages into the pipes.

Im sorry but this is misinformation. The reason we (I am an electrician) ground copper water pipes is because in subdivisions where copper piping is used, it forms the grounding grid for us so no ground plates need to be buried. this is how new homes are grounded, using buried plates or probes because most use non conductive water pipes.