Stray Voltage?

[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.