As understood in the N.E.C. concrete is considered as ground.
An office on slab w/ground water issues, would be considered as an ideal
ground.
Therefore the concrete floor is the counterpoise.
Look around near the Electrical Service Entrance. For anoffice bilding,
should be in the rear of the building, outside. look for a wire bolted to
the building frame. better yet look at the Electrical blue prints for the
for the building and iron frame.
concrete encased electrodes found in 250.52
A “Ufer” *ground* is slang for what the *National Electrical Code* (*NEC*)
addresses as a *concrete*-encased *grounding* electrode. The term “Ufer”
does not appear in the Code, but many in the industry use it.
a “made electrode” is ... water pipe, a *concrete encased electrode*
(typically re-bar), and structural steel
Section 250.50 requires a *concrete*-*encased electrode* to be connected to
the grounding electrode system if it is *present*
On Wed, Apr 8, 2015 at 10:47 PM, Jim Lux <jimlux@xxxxxxxxxxxxx> wrote:
> On 4/8/15 7:31 AM, Tim Flood wrote:
>
>> I would like to install a small TC, 3" dia. sec., in my office. The floor
>> is a carpeted slab and we have ground water issues which probably would
>> prevent drilling a hole through the slab for a ground rod.
>>
>> Possibly, simply drilling a hole into the slab and istalling a metal
>> anchor
>> for a ground connection would work. (?)
>>
>> Any suggestions for a ground system that is not too obvious?
>>
>> for that sized coil you don't need an "earth" ground.. You need a
> counterpoise under the coil. Make the radius approximately equal to the
> height of the topload above the counterpoise.
>
> Counterpoise can be chickenwire, hardware cloth, finely crafted silver
> sheets beaten into an elaborate pattern, whatever you fancy.
>
> I've stuck chickenwire to a piece of carpet that I can roll out under the
> coil.
>
> The cold end of the secondary goes to the counterpoise with a shortish
> wire. Then also connect the counterpoise to the "green wire ground" for
> safety's sake. (so nobody gets a shock if they touch it)
>
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