On 25/10/2007 7:08 AM, Horace Heffner wrote: > > On Oct 24, 2007, at 10:54 PM, John Winterflood wrote: > >> The important thing about a Faraday cage is that inside it you >> cannot tell anything about electric fields or electric potentials >> that exist outside. You can't tell (in theory at least) whether >> the cage you are in is grounded, or sitting at 100kV, or on the top >> of a Tesla coil and being oscillated plus and minus to many megavolts. >> >> In this Ron's case however there is an "ground" wire entering the >> cage and who knows what potential difference exists between the >> cage and the wire entering it until he measures it. This is the >> important thing - it doesn't matter whether either or neither are >> grounded - it just matters what is the AC and DC difference in >> potential between the wire entering and a well constructed cage. > > Good point. Another option along the same lines might be to simply > strip a section of the ground wire and connect the ground wire to the > faraday cage at the entry point using an alligator clip. It the > lights go out then the power is from an external source.
If the lights go out when the faraday cage is internally grounded it may just mean the apparatus requires an external ground but it would not prove the power source is RF. To know for sure, you would have to see how the apparatus behaves far from significant RF sources when the faraday cage is externally grounded... or have the owners of the RF towers turn them off. ;-) Harry
