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Tesla coil and high voltage demonstration safety

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aonomus

Thu May 14 2009, 07:49AM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

So I've seen the topic come up a few times and I thought I'd take a poll of the communitys thoughts. Once enough points/guidelines have been discussed, I will make a page on the wiki for future reference.

So (at 3:40AM) the things that come to mind are

- Safe observation distance
- Spectators with biomedical devices
- Ozone, nitrogen oxide generation
- UV (and radiation?) emission
- Noise emission
- Legal considerations
- Venue considerations
- Equipment safety

- If you want to contribute, please put the subsection and group your bulletpoints underneath each one.
- Note that this is for any high voltage demonstration, (Tesla coils, jacobs ladders, pulsed power, etc)

Firefox

Thu May 14 2009, 08:04AM

Registered Member #1389 Joined: Thu Mar 13 2008, 12:50AM
Location: Pittsburgh, PA
Posts: 346

One thing that comes to mind a big red button that kills the power instantly. Solid state or latching relays come to mind as being good candidates for this.

Killa-X

Fri May 15 2009, 01:52AM

Registered Member #1643 Joined: Mon Aug 18 2008, 06:10PM
Location:
Posts: 1039

Firefox wrote ...

One thing that comes to mind a big red button that kills the power instantly. Solid state or latching relays come to mind as being good candidates for this.

Big red button....Are you saying hack an Easy button into a higher rated main-power button? And somehow take Easy off and make it just a KILL? That was easy! I recommend this for an easy big-button :)

rp181

Fri May 15 2009, 02:59AM

Registered Member #1062 Joined: Tue Oct 16 2007, 02:01AM
Location:
Posts: 1529

Better yet a dead mans switch, so power is cut off when the hand leaves. I think you have the list pretty well covered. There is also the possiability of power consumtion issues, and mechanical workings.

Bjørn

Fri May 15 2009, 10:46AM

Registered Member #27 Joined: Fri Feb 03 2006, 02:20AM
Location: Hyperborea
Posts: 2058

- Safe observation distance
The device should be placed so high off the floor that children can't reach if they try (the presence of children or not is irrelevant). The observation distance should take into consideration that people some times trip and fall, so there should be rooom for people to leap forward and fall before reacing the device.

- Ozone, nitrogen oxide generation
Devices that are close to 1 W per cubic metre of air contained in a room have the potential to produce enough ozone to make people so sick that someone is likely to call an ambulance and possibly the police. Different devices produce different amounts of ozone, telsa coils are not too bad, lifters can be very bad.

- Equipment safety
If there is a loss of power the device should shut it self off automatically so that it needs to be manually restarted when the power returns. A solid state switch is not a good idea since they have a tendency to go short circuit when they fail.

Cesiumsponge

Fri May 15 2009, 12:15PM

Registered Member #397 Joined: Wed Apr 19 2006, 12:56AM
Location: Western Washington
Posts: 125

Address the possibility of being mildly shocked from coming into contact with surrounding metallic devices on more powerful coils during operation. People should be aware of this so they aren't touching hand rails or keys or other such things unless they want to become an involuntary demonstration tool.

syntroniks

Fri May 15 2009, 01:09PM

Registered Member #1530 Joined: Tue Jun 10 2008, 03:34PM
Location:
Posts: 32

Cesiumsponge wrote ...

Address the possibility of being mildly shocked from coming into contact with surrounding metallic devices on more powerful coils during operation. People should be aware of this so they aren't touching hand rails or keys or other such things unless they want to become an involuntary demonstration tool.

On that line of thinking, try to persuade the audience to remove any easily removable metal items they might have, keys, belts, I am not sure if piercings make the cut, but I don't have any

Makes me wonder what might happen to people with metallic work inside their bodies, best situate them near the rear. This is, of course, for the larger coils. Mine at half-power is very harmless, safezone is ~3 feet away

HV Enthusiast

Fri May 15 2009, 02:39PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
Location:
Posts: 3068

syntroniks wrote ...

On that line of thinking, try to persuade the audience to remove any easily removable metal items they might have, keys, belts, I am not sure if piercings make the cut, but I don't have any

This isn't an issue, even with the largest coils. The only types of coils this would truly be an issue with are CW type coils (i.e. SSTCs which are running at CW duty levels) and even so, only when you are pretty close to the coil.

With disruptive coils, your audience will always be farther away than to have any effects of field affecting them and the larger the coil, the farther away you'll want your audience to be.

Regarding pacemakers, there is evidence that states the fields in tesla coils don't affect them either (Dr. Resonance for example has one and works with Tesla coils all the time), but general practice is to always tell people with pacemakers to leave the area or stand far back - just as a precaution.

aonomus

Fri May 15 2009, 03:03PM

Registered Member #1497 Joined: Thu May 22 2008, 05:24AM
Location: Toronto, Ontario, Canada
Posts: 801

The Ontario Science Centre has a big bipolar spark gap coil, and it does have a yellow line marked on the floor with many signs stating that they are entering an area that they are there at their own risk, and the presenter does ask anyone to move away.

Even biomedical devices such hearing aids, insulin pumps, etc could be affected, each one is different.

Cesiumsponge

Fri May 15 2009, 10:13PM

Registered Member #397 Joined: Wed Apr 19 2006, 12:56AM
Location: Western Washington
Posts: 125

Dr. GigaVolt wrote ...

This isn't an issue, even with the largest coils.

I'm not sure about that. This video of the Griffith Observatory rotary spark gap tesla coil shows that the coil does just fine with the curator/guide drawing arcs off a nail on the wood display panel up front when the coil is running. It's not an especially monstrous coil either. It all depends on how your demonstration is set up and the distances involved.

Dr. GigaVolt wrote ...

Regarding pacemakers, there is evidence that states the fields in tesla coils don't affect them either (Dr. Resonance for example has one and works with Tesla coils all the time), but general practice is to always tell people with pacemakers to leave the area or stand far back - just as a precaution.

I would err on the side of caution when possible. It is everyone's freedom to make their own personal choices but you as a demonstrator should inform them of the probable/improbable risk up front. They can then make their own choice after. Out of curiosity, is there actual evidence or just anecdotal cases on pacemakers? I tend to be skeptical. We were told for decades that streamers were relatively safe because of the skin effect which was well known with metallic conductors...except it doesn't necessarily apply on humans in quite the same way.

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