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Re: [TCML] Grounding Coil to Water Pipe
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 places. 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 rod).
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.
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.
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.
All of which is to say that if it was me I wouldn't risk it. Generally speaking I wouldn't run my coil near any kind of antenna.
And yea, I know coils are lousy RF transmitters, and I've even read the very cogent mathematics done by some engineers on this very mailing list. But what I'll say is that your satellite dish isn't exactly any sort of significant distance away. If it was in the next block or next door at the neighbor's - probably no issue. But if you're close enough to be connecting to the same water pipe, aie yai yai. I wouldn't do that even if I disconnected it.
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.
Recently, I repaired my garage door opener. Only to have it fried again.
But this time, not by my coil - but rather, by a Van De Graff generator I built and ran in the garage. That's right. My pipsqueak VDG running at about 450KV static fricking electricity actually induced sparks on a bicycle hanging from a metal bike-rack-hook about 10' away - maybe farther. Now - get me right on this - the sparks didn't travel from the VDG sphere to the bike - there were no sparks on the VDG. But there were sparks between the bike frame and the hook when the VDG was running. If I hadn't seen it with my own eyes, I would have never believed it possible at that distance. And I could hear the crackling in the vicinity of the opener, which is closer than the bike. Now these were little sparks that you could only see in the dark. But they were sparks visible across the garage, and I know well enough they'll fry any static sensitive electronics.
So now my garage door opener is fried again.
All of which is my way of saying, if you want to keep your sanity and your stuff working, just keep your sensitive electronic stuff well away from your coiling, and on different circuits.
Joe
On Aug 28, 2010, at 2:01 PM, Brandon Hendershot wrote:
> Hi Everyone,
>
> I got DirecTV the other day and notice that the installer grounded the satellite dish to the protruding water pipe leading up to my garden hose. I'd never thought to ground there before! But I've got a few things I'd like to run by you all before I try it there;
>
> 1. The running water shouldn't be affected by the coil due to the 'skin effect' factor. It should limit the current only to the surface of the pipe, right?
> 2. The satellite ground should be disconnected before powering on the coil, right? Seems like a bad idea to pump thousands of volts into a satellite dish ;P
> 3. The pipe should provide sufficient RF ground, yeah?
>
> I've searched the list, but I didn't see anything particularly definitive on the subject...
>
> Thanks everybody!
> Brandon
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