RE- Short circuit
Subject: RE- Short circuit
Date: Fri, 06 Jun 1997 11:00:00 GMT
From: robert.michaels-at-online.sme-dot-org (Robert Michaels)
Organization: Society of Manufacturing Engineers
T> From: gweaver <gweaver-at-earthlink-dot-net>
T>While running my 1350 watt Tesla Coil today something very strange
T>The ON/OFF switch shorted itself closed and I could not turn the Tesla
T>off. I tried the switch several times and it refused to turn off. I
T>walked a few steps to unplug the cord from the wall when it suddenly
T>on the side of the cord about 2" from the plug. The arc turned into a
T>hissing ball of fire. For several seconds the Tesla Coil was still
T>sparks and the extension cord was arcing also. I unplugged the cord
T>found the copper wires were melted and burned in half on the cord. I
T>high voltage can do strange things but never had this happen before.
T>only the switch had gone bad or only the cord had fried I would guess
T>died of old age. But 2 things fried within seconds of each other
T>think it was caused by something. Has anyone ever had something like
My very strong sense is that =you= were using a Radio
Shack switch, it's ilk or it's kith. (Or was it the
pull-cord switch (yike!) found on the side of some
Dear people: The one and only way to =safely and reliably=
control power to any Tesla coil outside the
smallest neon/OBIT class (maybe) is with an
industrial/commercial Disconnect Switch.
Such switches amount to nothing more than an old-style knife
switch mounted inside a steel enclosure. A handle extending
from the side of the enclosure allows the switch to be
operated with the grounded (hint!), steel (hint!) cover of
the box closed (always!).
Such Disconnect Switches (sometimes called safety switches)
are ubiquitous in controlling industrial and commercial
equipment and are available at any good hardware store or
building supplies dealer. They are available with/without
arc-suppressors built in and with/without fuse clips.
Cost is $30-$40 and up depending on current/voltage
ratings which begin typically at 30-A/250-V.
- - - - - - -
When working alone (not such a hot idea, I admit) with higher
power coils, I've used a timed switch: A disconnect switch
rigged to turn off automatically after 5-10-30-120-whatever-
seconds. That way, if I became cross-wise of something which
prevented immediate personal access to the switch, I might live
to tell about it (I apparently have).
Tesla coils are wonderful things to turn on. They're
even nicer to turn off when the need arises.
Yours against careless-coiling,
in -- Detroit, USA