RE: Spark Gap/ UV Re: frequency of electromagnetic radiation

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Mark Dunn" <mdunn@xxxxxxxxxxxx>


My comments are with regard to arc welding.  Whether or not they apply
to a spark gap depends on its similarity to welding arc.

The welder is protected by a hood with shaded lense.  Without the shaded
lense he would have flash burns in a matter of minutes(Flash burns are
in the eyes and can be very serious).  The choice of shaded lense
depends on the sensitivity of ones eyes.  The shaded lenses are
numbered.  The higher the number, the darker the lense.  We have a
welder with sensitive eyes who uses a #13 lense.  We have another that
can get away with a #8 lense which is approximately the lense typically
used in Oxy-Acetylene goggles(Oxy-Acetylene flame is not as bright as
welding Arc).

In addition, the welder wears protective clothing to prevent UV burns to
the body.  Sometimes if his shirt pulls out of his pants during the day
he will go home at night and find a 1st degree sunburn along his pants
line on his back or side.

Others who work in the welding shop area(but are not welders) generally
wear the Oxy-Acetylene goggles to avoid Flash Burns from reflected
welding arcs.  The also keep there bodies covered to avoid the UV burns.

Once I spent about 4 hours in the welding area with my back to the
welding and experienced a sunburn like burn above on my neck above the
collar and below the hairline.  I've also had minor Flash Burns one time
from reflected arcs.  Never even looked at the arcs and got it.  Eyes
were bloodshot and painful for 3 days.

If you were running a Spark Gap Tesla Coil continuously for hours at a
time I believe this would be an issue.  If you want to stare directly at
the arc you need a welding hood and shaded lense.  Likely a lense shade
of #10 to #12 is would be sufficient for most people.

Mark R Dunn, P.E.



 >      I was always taught that the spark gap gave off ultra-violet and
 > thus should not be looked at. Is this correct, as a general rule?
>     The spark gap, as such, will have some UV.
>     Depending on the coil size, possibly enough to
>     be damaging.  A welding arc, with more power,
>     and specific materials makes more UV, and the welder is
>     Looking Hard At It for hours at a time, so more
>     precautions are in order.  Care in any case is a good
>     idea.

>       best
>        dwp