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How good is my ground?
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From: Jim Fosse [SMTP:jim.fosse-at-bjt-dot-net]
Sent: Wednesday, March 18, 1998 2:09 AM
To: Tesla List
Subject: Re: How good is my ground?
Steve,
>Performance of the coil is about the same as when I was using the house
>grounding system. This new ground rod is totally isolated from the
>house ground.
I've never noticed a difference in my TC's performance with different
grounding wires. I have noticed a difference in the amount of damage
I've done to my home electrical controls - Since I've started using
both #4 welding cable and a 2" wide strap of Al tape, I've not taken
out any of my home electronics. (Although I still confuse the timer on
my sprinkler system every time I light 'er off;)
>
>A volt meter reads about .5 vac from a wall outlet ground terminal to
>the new rod. I also get a reading of about .36 vdc between the same two
>points. Trying to measure resistance is futile with this much AC/DC
>riding between the two points (at least with my Radio Shack digital
>voltmeter :-).
On 2/2/97 I measured 12.6 ohms -at- 1kHz between my TC ground and my SWL
antenna ground 40' away. Tonight (3/17/98 off list topic about El
Nino~) I measured 12.0 ohms -at- 1kHz with my LCR bridge. My faithful
Simpson 260 has died so I can't make an Analog measurement:( My new
DMM refused to measure the resistance. I do however measure 0.1 Vac
and 0.4 Vdc between these 8' ground rods using said DMM.
TC wise: I could light a NE2 lamp between my TC's ground bar and my
ground rod with #6 stranded wire as the main ground using a thevanan
(sp) connection. When I changed to #4 welding cable, the NE2 would
just light. When I added the 2.5" wide Al "Duct Tape" in parallel with
the #4 welding cable, I could not light the NE2. All these test were
with an 8" by 20" secondary powered by a 15kV 60mA neon that produced
about 3' arcs to a ground electrode. NE2 lamps ignite at 90 volts and
maintains at 60 volts.
Additional notes in my log indicate that for air discharges, the
ground rod was the negative terminal. For arc discharges to an
electrode grounded to the TC's ground bar, the NE2 indicated AC
between the ground bar and the ground electrode..
aside: 2 years ago the (brackish) ground water table was 12' below
ground. I wanted to see if the 575% of normal rain fall last month had
raised it any. I can't measure any difference. I guess that means I'll
have to pull the sanitary cap off of my well and drop a float to
measure the water table level. (It MAY have risen, but "polluted" the
salt water with rain water. I live a mile and a half from the San
Francisco Bay which is salty water)
>
>So, is this ground any good? It seems to work ok, but I'm curious if
>there is a straighforward way to measure the performance. Maybe try to
>drive some voltage between the two ground points and measure the
>current?
>
Buy a couple of NE2s from Radio Shack and use one as a voltage
indicator. Wire them with small gauge wire between your TC's ground
point and your ground rod. Then try paralleling your existing #6
ground wire with some Al foil tape from the hardware store. You will
not see any difference in the TC's output, but you will reduce the
risk to the electronics in your home.
Regards,
jim