[W2CRA] RACES Room Floor Resistance

[William Powell]

All,

This afternoon, Sandy (WA2JVK) stopped by with a Megger to test the resistance 
of the RACES room floor.
For those who might not be familiar, the RACES room is located in the center of 
the building with no effective RF ground; the HF antenna tuner is HOT with RF.

In rebuilding the room, we glued 12" wide heavy copper foil to the floor in the 
form of the letter E where the I part of the E is at the back of the room, the 
center of the E runs down the center (under the consoles) and the top and bottom 
of the E along the walls.  Then we built an 18" x 18" grid of heavy 2 1/2" 
aluminum foil tape over the entire floor.  Finally, the floor was given 2 coats 
of conductive paint, the 1st coat "flowed" between the copper / aluminum 
overlaps and the second poured and spread evenly over the entire surface.

The question was "Just how conductive is the paint?"
With the megger attached to a 2" sq. piece of copper placed on the paint, in the 
center of an 18x18 grid we measured < 200,000 Ohms but > 100,000 Ohms.  A Fluke 
digi multimeter reads ~136,000 Ohms but the reading is inconsistent as the 
voltage across the probes is very low: not enough to "energize" the floor paint.
So . . .
The electrical resistance of the conductive floor paint is "greater than copper" 
and "less than air".  Good enough to be "anti-static" but unknown if it enhances 
the safety (potential difference).

I have yet to determine how good the RF ground is as I have nothing to compare 
it with as the building ground wanders all over the place and is NOT an RF 
ground.
Any ideas for a test plan?  
Remember - the room is in the MIDDLE of the building; it's 40' from the nearest 
dirt.

Bill Powell - WB1GOT