Re: *****Grounding question

["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>



Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<dbanse-at-comcast-dot-net>
> 
> I have a 15kV60mA NST....
> 
> I have an older house where none of the sockets are grounded....(they
were all
> 2 prongers....I just 'put in' three prong outlets....(but no wire to ground
> with)
> 
> I want to test my NST with just the spark gap, and the capacitor.

This is hard on the NST... Why not just run the NST with the gap alone...

> 
> What will happen if I just plug it in with no variac or anything else?
> Will I get the shit shocked out of me?

Well.. probably not that bad, but it very well might hurt a lot, and you
might start a fire inside the wall..

The risk is that one of the HV terminals will short to the case or to the
low voltage primary (the short might be a spark breakdown inside the
transformer, and be invisible, and not present when transformer's not on).
Then you've got several bad scenarios:

1) Case at HV
2)  case at HV shorted to power line, putting HV back into the line, where
it will hopefully be shorted to ground by something along the way (loose
screw, corona discharge, the power companies transformer).  Depending on
all the impedances along the way, the voltage might be fairly high (several
hundred volts).. enough to breakdown the feeble insulation designed for
300V (when it was newly installed).  If your house is wired with "knob and
tube"... words fail me...



> 
> My NST has two output terminals....which are obviously the 'OUTS'
> 
> It also has a 'GRD' terminal on the other side...which I am pretty sure means
> 'Ground'...........do I use this for anything, and if so, what do I
connect it
> to? ...a water pipe or something?
The third prong on the plug, which should THEN be connected to a water pipe
or something.  

Seriously, if you're going to be fooling with HV, you do need to pay
attention to safety grounds.  When you start making RF High Voltage the
problem gets worse.
> 

For what it's worth, putting 3 prong outlets in without grounding the third
prong is an egregious safety hazard (and probably illegal as all get out,
but that is really beside the point.. we've all done things that are
illegal but safe).  At least with the two prong outlet, you know it's
unsafe, but some unsuspecting person might think that the grounded outlet
really is grounded.  There is a big difference in design between "double
insulated" appliances (designed for two prong ungrounded outlets) and
appliances designed for a third wire safety ground.

In something designed for ungrounded operation, a single failure typically
cannot result in line voltage being applied to the surface or operating
controls.  In things designed for a safety ground, a short of line to case
will result in fault current through the safety ground, hopefully blowing
the fuse or circuit breaker, and in any event, the case won't be at 120V
relative to ground.

This is particularly important if you are, for instance, standing in bare
feet on the concrete/tile floor.

Bear in mind also that ground fault interrupters (like the ones on
hairdryers, etc.) won't work with ungrounded outlets (at least in the
preventing shocks sense...).  You don't want to return to the days of 16
people a year dying from using a hairdryer in the shower, do you.

> Thanks,
> Newbie coiler,
> HyFlyOne