Re: Safe Sparks

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Jim Lux by way of Terry Fritz <twftesla-at-qwest-dot-net>" <jimlux-at-earthlink-dot-net>

Interesting.. at 196 MHz, of course, skin effect will put most of the power 
at the surface (unlike at 100 kHz'ish TCs, where the high resistance of the 
body makes for a fairly large (RF)skin thickness).  I wonder how the poor 
guy got 2A at 196 MHz? That's   TV channel 10 (192-198 MHz) in the US (I 
don't have the channel frequencies for Australia handy..but it's in the 
same ITU band), and I'll bet you could get 2 Amps (if not a lot more) if 
you happened to grab the  transmitting antenna or an exposed feed terminal. 
50 kW at 50 ohms is around 32 Amps...

I'd change the first line of the abstract to be:
RF electrocutions are not commonly reported.

I'll bet that there are a lot more RF burns that actually occur than are 
reported.   Only the most egregious or ones with lasting effects would show 
up in a doctor's office.


At 06:06 PM 12/2/2002 -0700, you wrote:
>Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" 
><DanReind-at-aol-dot-com>
>
>Hello all,
>
>I was doing some digging on pubmed as part of my work, looking for some 
>information on radiofrequency burns.  Found an abstract for a very high 
>frequency burn that I thought might be off interest.
>
>Cheers,
>
>Dan Reinders
>
>
>
>"Occup Med (Lond) 1999 Sep;49(7):459-61 Related Articles, Links
>
>
>Radiofrequency electrocution (196 MHz).
>
>Hocking B, Westerman R.
>
>International Diabetes Institute, Caulfield, South Vic., Australia. 
>bruhoc-at-connexus-dot-net.au
>
>Radiofrequency (RF) electrocutions are uncommon. A case of electrocution 
>at 196 MHz is presented partly because there are no previous reports with 
>frequencies as high as this, and partly to assist in safety standard 
>setting. A 53-year-old technician received two brief exposures to both 
>hands of 2A current at 196 MHz. He did not experience shock or burn. 
>Progressively over the next days and months he developed joint pains in 
>the hands, wrists and elbows, altered temperature and touch sensation and 
>parasthesiae. Extensive investigation found no frank neurological 
>abnormality, but there were changes in temperature perception in the palms 
>and a difference in temperature between hands. His symptoms were partly 
>alleviated with ultra-sound therapy, phenoxybenzamine and glyceryl 
>trinitrate patches locally applied, but after several months he continues 
>to have some symptoms. The biophysics and clinical aspects are discussed. 
>It is postulated that there was mainly surface flow of curr!
>ent and the micro-vasculature was effected. Differences to 50 Hz 
>electrocution are noted. Electrocution at 196 MHz, even in the absence of 
>burns may cause long-term morbidity to which physicians should be alerted. 
>Safety standards should consider protection from electrocution at these 
>frequencies."