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Re: [TCML] Grounding Coil to Water Pipe

Joe Mastroianni wrote:
Well, ground should be ground, I suppose.

I run my coil to a separately pounded-in 8' ground rod.

No need to worry about the water in the pipes, that's for sure.   I
think grounding your home to a water pipe is even within code in some

almost nowhere is that within code these days. water pipes are required to be grounded, but cannot serve as the grounding electrode. Too much plastic pipe.

 Before my ground rod I ran it to the ground in my house
(the 3rd prong of the outlet plugs), which is created at my service
inlet by connection to an 8' ground rod + connection to water pipes.
(and in my town, grounding to your water pipes will at least pass
inspection - though I think you have to back it up with a ground

An 8 foot ground rod will generally not comply with code, unless the entire rod is buried. The code (where code == NFPA 70/National Electrical Code) requires 8 feet of rod below the surface, and furthermore, the latest versions of the codes (last 10 years at least), do not allow a rod to serve as the sole grounding means.

Using the water pipe as a grounding electrode hasn't been usable as the sole grounding means for quite a while.

Now,  there may have been an issue with this as electrical items on
the same circuit when I ran my coil RF to the house ground, which
shared that physical ground wire before it reached the service inlet.
Items plugged in there did actually suffer bad transients.  But I
can't say that was because my coil was detuned or because my RF
ground was the same as my power-supply ground.  Either way it was
badness for me.

Yep.. Shouldn't be using the electrical safety (green wire) ground as a Tesla coil RF ground. the two should be connected (bonded in code-speak), but you shouldn't be expecting any current to flow in the safety ground wiring.

I guess the question is whether or not there is sufficient RF
reactance or distance between the coil and the zero-potential of the
earth to let the voltage rise somewhere between.  If this was ham
radio, and you were pumping 1.5kw of RF at a couple megahertz into an
antenna, you'd want to be as close to your grounding source as
possible, and connecting to the pipes in your home could actually
create some parasitic issues.

The code (and good practice, besides) requires that all grounds be bonded together.

But for a coil, running at what amounts to very low frequencies in
the 100s of khz range, I think you'd have to be mighty far away
before you had any of those sorts of issues.

The problem is not inductance or resistance, per se, but inducing currents in the grounding wiring.

I used to completely disconnect my garage door opener when I ran my
coil in my garage, and it fried anyway, even though the thing is a
motor in a faraday cage.  Currents were induced by the tiny hanging
antenna or the rather large "antenna" formed by the gantry that pulls
the door open and closed.

or, more likely, the wires that go to the push button or safety switches.

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