[Vwdiesel] Re: Glowplug used for preheating swirlchambers at 6 volts.

Sandy Cameron scameron at compmore.net
Thu Feb 24 08:47:07 EST 2005

At 03:22 AM 2/24/05 EST, you wrote:
>> There is no connection between any of the
>> circuitry on the primary and that on the secondary.
>  I have an interesting one.  ATI all in wonder card and when I connect the 
>TV cable to it, there's a pretty good "bite" if you touch the case and 
>shield-grounded part of the cable connector.  Other interesting thing 
>is now when the cable's disconnected, the neon light in the switch 
>array won't light up.  Strange.
>     Loren

Not uncommon. Since we assume you are powering your computer with a 3 wire
cord from a U-ground outlet, it is connected to your utility ground. if you
are a rural customer, your neutral is bonded to your ground.
The utility neutral  is almost never at ground potential, due to resistance
in the neutral going back to wherever they have bonded it to ground, there
will be a voltage difference between the local ground, and the neutral.

 It's called a ground loop. (common in rusty rabbits too, makes the
instruments go funny)(

The bane of dairy farmers, who cut the legaly required bond between ground
and neutral, build wire mesh ground planes into the concrete of their
milking parlours, and do all sorts of things to make the cows happy and let
their milk down.

one volt of 60hZ AC is enough to drop the herd's production 20%, cause
mastitis, and make dairying a nightmare.

Furthermore, the cable company is not totaly sanitary either, their lines
strung under hydro wires on the same poles, can build surface voltage by
induction, capacitive coupling, but mostly because they bond the outer
shield to faulty utility grounds along the way, and deliver a volt or 2
difference from the outlet grounds to your house.

You can sometimes draw a spark from the cable connector to a water tap in
your house.

It's usually a low voltage, not lethal, but sometimes surprising if not

I have survived more than 50 years as a broadcast engineer, working on
transmitters with up to 12,000 volts inside, also had a few years experience
in cable tv outside plant. and quite a bit of electric power experience as
well. I have experienced all of the above.

My brother-in -law's dairy farm was the greatest challenge..
Devices have been designed to decouple the neutral from local ground, but
retain the safety requirement.
But the best solution so far is to completey bond all metal in the milking
parlour, and include a wire mesh in the concrete floor at construction,
which is also bonded. 
The reinforcing steel in the concrete is also bonded by welded wires, so the
cows are milked in a low voltage Faraday cage.

Grandpa's farm was never like this!


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