[Prev][Next][Index][Thread]

Re: Just wonderin' (fwd)



Tesla List wrote:

> Original Poster: Terry Fritz <twf-at-verinet-dot-com>
>
> I too would be very cautious of HV gloves.  The power company tests such
> things often with special equipment to insure they have not been punctured.
>  Also a small arc could burn or blow a hole and them and get to you.  The
> people at the power company have a lot of training and experience that also
> help them to do the dangerous work they do.  Almost always they are also on
> a thick non conductive mat or in the safety of their isolated "cherry
> picker" basket when working on live power.  They take risks because they
> often have to.
>
>         Personally, given the choice between gloves and the off switch.  The
> gloves would not be consideration...

I'll third that motion.  I have been responsible for the testing of HV
gloves in
the past.  I used to see an uncomfortably high percentage of failures.  No
lineman worth the ashes that would be left will rely exclusively on HV gloves.
The gloves are a last-ditch backup for when accidents happen.  You will see
linemen handling hot primary cables with gloves but they're almost always in an
insulated bucket truck.

I have a pair of HV gloves that I use whenever I'm around lethal voltage but I
also use the rest of the protective suit.  That is, insulating blankets and
sleeves and insulating mats to stand on.  People tend to get in a complacent
mood regarding pole pigs and even high current NSTs.  A pig used in a tesla
coil
(or neon bombarding) situation is absolutely the most dangerous application
possible, much more dangerous than when connected to the utility.  The utility
high voltage primary distribution wiring has enough energy behind it that
when a
lineman makes contact, he is usually blown away.  Nasty burns, sometimes lost
fingers and toes but many survive.  That same HV limited to a few amps is just
perfect to grab hold and keep you on it for the second or so it takes to stop
your heart.

HV gloves are tested by filling with water, immersing in a water bath and
applying the rated test voltage (usually 4X the service voltage) across the
gloves.  More than 1 ma of current and the glove fails.  The testing rig we had
at TVA contained a huge platform mounted pig and generally would blow a decent
sized hole in the glove as it failed.  I do NOT suggest trying this testing at
home.  I send my gloves off every 6 months for testing and replace them every 2
years.

Gloves that have failed or are out of date should have their approval decal
ground off.  A lot of these failed gloves are showing up surplus, most notably
at Northern Hydraulics.  Everything on the cuff except the size has been ground
off.  These gloves have failed their testing.  DO NOT USE FOR HIGH VOLTAGE!!!
They make nice chemical gloves but that's it.

John
--
John De Armond
johngd-at-bellsouth-dot-net
Neon John's Custom Neon
"Bendin' Glass 'n Passin' Gas"