Stray Voltage?

[syncro]

Do I have a problem with stay voltage?

Voltage with nothing plugged in: 5vac
Voltage with Odyssea pump: 35vac
Voltage with Eheim 1000 pump: 15vac

In the past week I've had one clownfish jump out and had trouble with my aquarium controller (solved by the vendor - sounds like configuration data changed in a way that isn't possible by the end user).

It sounds like pumps normally induce 20-30v of voltage because of the rotating magnet. I'm guessing this is ok because very little current will be induced.

I am measuring with a multimeter with one probe in the water and one probe in the third (ground) opening on the outlet. Outlet is GFCI. No ground probe.

[Mike-fish]

How do you have 5vac with nothing pluged in. Any probes or " leaky" timers around

[syncro]

Stray current with everything plugged in and running: 0 mA

[syncro]

How do you have 5vac with nothing pluged in. Any probes or " leaky" timers around

Everything was physically disconnected from the outlet.

I believe this is caused by different ground references. With nothing plugged in, the tank is not grounded. So any induced electrical charge (e.g. static electricity by brushing against the glass) will create a voltage difference. I could be wrong, I don't know this stuff that well.

[Mike-fish]

i follow your thinking if your worried about it just invest in a ground probe. with all running it sits at 0 there shouldn't be a problem

[Baldy]

A ground probe in a tank with stray voltage induced through powerheads, heaters ect, will turn stray voltage into current. and if the current gets high enough will trip a GFCI

[syncro]

A ground probe in a tank with stray voltage induced through powerheads, heaters ect, will turn stray voltage into current. and if the current gets high enough will trip a GFCI

Can powerheads induce enough current to trip a GFCI (5mA)?

How does a heater induce current? Does it have something to do with the heating coil? I understand powerheads induce current by creating a moving magnetic field.

[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]

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.