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How can I ground a Tesla Coil if I don't have access to the ground outside?

For a project in school, and as part of a speech I'm delivering on Nikola Tesla, I had hoped to have a relatively small Tesla Coil to bring in and show off. The only trick is, the classroom is on the second floor, there are no windows, and it just today snowed where I live (so taking the demonstration outside doesn't seem like a good idea)... So I have really no idea how to ground the secondary on this beast.

I've read a lot about Tesla Coils and seen a lot of schematics, but nobody can give me a good answer for grounding them except for "drive a metal rod into the ground". And despite that, I see videos on Youtube of small tabletop coils (of the scale I wish to build) that don't appear to be connected to anything as a ground other than the mains outlet.


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It turns out you can build an ungrounded coil, but it will increase the danger of shocks. The ground is a stable "zero point" for the coil. Without it, conductors float at various voltages instead of being neutral. Things act as isolated capacitors that can deliver unexpected shocks.

I have to say that I don't fully understand the explanation I read in the Tesla Coil book.
~Bob~
You can use a chicken net about 10ft.sq for the grounding....u dnt necessarily need to dig a 5ft for grounding if u dnt feel like it...lol.....
Mr. Apol7 years ago
If you build a bipolar (horizontal secondary) Tesla coil, you don't need an external ground. See my Instructable "Tabletop Tesla Coil."

You can use what's called a counterpoise--a large metallic object placed on the floor at some distance. Connect your ground wire to it and it will act as a ground. Some people use metal trays or buckets, etc.
b-stro7 years ago
 If your school is built to code, any plumbing should also be grounded. So if you have a faucet or drain nearby, that could serve as your ground.
I would imagine you can ground it through the ground prong on a 3-pin wall outlet - you just have to make sure that it's actually grounded (surprisingly fewer schools are built to code than you might think).

Get an inexpensive outlet tester from a hardware store to verify that the wall outlet in your classroom is properly wired.  It should have three lights, with a diagram showing you what each pattern indicates about the quality of the outlet.  If it shows the ground is okay, then use it.

If not, it gives you a fun reason to complain to the principal.
I would not ground it to the mains ground.  That ground may be a high resistance ground meaning the voltage won't go directly into the ground and that everything that is connected to the ground will have a connection to the tesla coil and something is gonna break, melt, fry or otherwise impact your standing in the school.

Think of all those computers etc.  that might be connected to the same ground circuit.
Ungrounded Tesla coils are said to be unsafe. I only have experience with grounded coils. I made a small one that put out 2 foot sparks.

Schools are full of computers. Tesla coils can be a problem for computers.

I have Mitch Tilbury's book "The Ultimate Tesla Coil Design and Construction Guide" . I'll look for an answer later.
~Bob~
 
Re-design may be right, but I've run a Tesla coil without a ground, a ground to the main, or a ground to any water pipe.  Granted the coil is only 8" (20 cm) high.
Lots of the schematics that I've seen don't show a ground, or they show where the ground should be and it is connected somewhere else.  I guess it depends on the circuit as to what the ground does.
Re-design7 years ago
Take a look at what this site has to say about ground in the section labeled "grounding" about 3/4 of the way down the page.

If you can get near a window and run you ground wire out the window and into the snow that may be the ground you are looking for.

Have you gotten permission to operate your coil in school?

I can't see that happening in any of the schools around here.

Good luck.