Passing HF current through your body / Tesla Coils / Forums

Forums

4hv.org :: Forums :: Tesla Coils

« Previous topic | Next topic »

Passing HF current through your body

1 2 3 next

Move Thread

LAN_403

Steve Conner

Mon Mar 11 2013, 12:33PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Hi all

I found this interesting paper:

It has an IEEE/ANSI recommendation for the maximum high frequency current that can safely be passed through the body. At VLF frequencies, you can have roughly 1mA for each kHz of frequency flowing in a limb. (Limited by current density in the ankle or wrist. A more detailed discussion is on page 33.)

This seems to imply that you can pass a few hundred milliamps through your arm at Tesla coil frequencies, and so it is actually quite safe to light a low-powered filament lamp with current passed through your body. I've done it with a 30W, 240V lamp and suffered no ill effects.

HV Enthusiast

Mon Mar 11 2013, 01:45PM

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

Interesting paper.
What do they consider VLF frequencies?

Physics Junkie

Mon Mar 11 2013, 01:54PM

Registered Member #7267 Joined: Tue Oct 16 2012, 12:16AM
Location: Detroit, Michigan
Posts: 407

Yikes, so who wants to be the guinea pig on this one?

ScotchTapeLord

Mon Mar 11 2013, 08:02PM

Registered Member #1875 Joined: Sun Dec 21 2008, 06:36PM
Location:
Posts: 635

I don't know, this guy says higher frequencies are worse:

Much more credible than IEEE! ;)

Graham Armitage

Mon Mar 11 2013, 08:22PM

Registered Member #6038 Joined: Mon Aug 06 2012, 11:31AM
Location: Salado, TX
Posts: 248

LMAO - I want that guy as my Tesla Safety Officer !! Nothing could go wrong !

Marko

Tue Mar 12 2013, 10:16PM

Registered Member #89 Joined: Thu Feb 09 2006, 02:40PM
Location: Zadar, Croatia
Posts: 3145

Hi Steve and Everyone :)

Funny how in another thread I've read a claim of maximum permissible H field exposures on only a few V/m at Tesla coil frequencies (which, even more absurdly, decreases with the frequency!). In any case, I wouldn't take any of these as a rule above some basic sanity and ohm's law.

When lighting incandescent bulbs with Tesla coils, one would need to take care that his arm doesn't end up dissipating many times the power that's already dissipated by the body, which is 100W or so. If typical arm resistance is in range of few hundred ohms, the current indeed resolves to a few hundred miliamps. I certainly wouldn't take the above rule as meaning that one can safely pass 10A at 10Mhz through his arm!
I'm actually not convinced that frequency may have much to do with this, as long as it's well above cutoff frequency of the nerves.

As Steve already said, these experiments tend to concentrate the power in fingers, fists and ankles and that's likely the first place where damage would occur.
I once lit a 100W bulb that way for quite a long period of time this way by holding it only by a thumb and index finger, and got a weird pain in the thumb joint which went away another day. Couldn't figure it it was even related at all, but it till made me to put some sense into the thing, so I later used a 25W bulb and a big copper pipe as an electrode which I held firmly with both hands. This is the setup that I'd recommend for anyone who really wants to replicate this experiment. If I had to put a line somewhere, I'd call the maximum permissible rf current through palms about 100mA, because that was what I was able to pass without any ill effects!

Cheers,

Marko

g8gon

Wed Sept 25 2013, 09:05PM

Registered Member #2370 Joined: Fri Sept 18 2009, 02:15PM
Location: exmouth
Posts: 2

i have on occasion drawn arcs from a cw powered coil @ 2kw with a hand held 5ft flourescent tube..
no burning hands etc but i always suffer chronic hoarsness later in the day and for a few days after, such that i try to avoid the party tricks as much as possible now.. anyone else suffered hoarsness i wonder.. is it arcing from the tonsils i wonder maybe keeping the mouth shut would be better..

alec

Steve Conner

Wed Sept 25 2013, 09:45PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

I think hoarseness would most probably be caused by breathing the ozone and oxides of nitrogen from the sparks, both toxic gases.

I once got a really bad sore throat from practicing the Tesla guitar show in a room with a smoke machine and poor ventilation.

Dr. Dark Current

Wed Sept 25 2013, 09:56PM

Registered Member #152 Joined: Sun Feb 12 2006, 03:36PM
Location: Czech Rep.
Posts: 3384

I have seen people pass amps of RF current into their hand at MHz frequencies, of course it was always just for a moment

BigBad

Thu Sept 26 2013, 01:07AM

Registered Member #2529 Joined: Thu Dec 10 2009, 02:43AM
Location:
Posts: 600

I realised a while back that even when you hold a fluorescent tube near a Tesla coil and it lights up, of course the power/current for that is actually going through your arm; even though it's capacitively coupled through the glass.

I can't remember exactly how I did it, but IRC I did a BOTE on that current, and found it was much closer to the fatal limit than I would have preferred.

IRC it was a few tens of milliamps, I may have done the calculation wrong of course.

1 2 3 next

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob