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Re: Random TC Questions

Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>

----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx> To: <tesla@xxxxxxxxxx> Sent: Tuesday, March 15, 2005 6:34 AM Subject: Re: Random TC Questions

> Original poster: "Gerald Reynolds" <gerryreynolds@xxxxxxxxxxxxx> > > Hi Jim, > > Do you really think that tying the strike rail and secondary base to the > green safety wire is going to make the TC any safer??

I think that the counterpoise, or anything that you will be standing on,
that is connected to the bottom of the secondary should be tied to
protective ground (green wire). The idea is to minimize the possibility of
injury or fire in the case of a fault.  It's not unheard of for the 110V or
10+kV to short to TC components (something falls on the coil, you get a
flashover, etc.).  If I am standing on the concrete floor, or happen to be
touching something with a grounded metal case, AND I happen to be touching
the TC counterpoise at the same time, I don't want to be fried.

 If you think you
> need a strike rail then I'll let you touch the strike rail or base during
> operation.  If you tie it to the green safety wire then any strike to
> objects earth grounded will cause the return current to come back thru
> house wiring to find its way back to the base of the coil.  That could
> your computers plugged into the mains even if turned off.  If you think
> this is a code issue, then this has got to be an issue of  "can touch" and
> certainly not "intended to touch".  Then what do you do about the top
> load???  That can be touched too.  You, as operator, have the
> responsiblility to see that it is not.

Sure.. If you can set up your system so that it's entirely floating, and
that a strike never goes anywhere near a "grounded" object, you can not
safety ground the secondary.  However, that's a fairly big challenge.

As for RF return coming back through the "greenwire ground", that's why you
should put a choke in the connection.  The safety ground is for 60Hz, not
for RF.  However, whether it's explicitly connected or not, the streamers
can still put significant voltages into the house grounding system by
inductive coupling. The streamer is a fairly fast, fairly high current
transient (i.e. high di/dt) and the area of the loop is fairly large
(secondary, topload, streamer, whatever it hits, return path to secondary).

> > If the green safety wire is used to ground the TC (like for indoor > operation where an earth ground is not close at hand) then, as you say, a > counterpoise will be necessary to intercept any strikes and allow its > return current (and RF return current) to go directly back to the base and > not thru the house wiring.

If you don't have a counterpoise, where do you think the RF return currents
are going?  Why would they not follow the green wire ground back through the
interwinding capacitance of the HV transformer to your coil?

> Gerry R.