I have never heard of this practice before but is there a specific proceedure for measuring resistance from the ground grid to earth? What typically do you reference in this case ? Another gound grid? Water pipe?
I don't know exactly what you want to know? I guess you want to know the grounding resistance. if it is, I try to answer the question as I know.
This is an important parameter for a building design, project check and accept and later maintainance, because every building has to have a groung grid net, but how to measure the parameter, is not everyone aware of. generally speaking we use a Mega ohm meter to do it.
the meter has three terminals, one is common, onle is current generator and the last is voltage measure terminal. we used to lead a wire as long as 40M distance to crurrent terminal, rotate handle on the meter to gene\rate a high voltage, some can get 2000v apply to the wire, then we use another wire at middle distance of 20M measure its voltage, we can read ohm value at the meter scale. diffenet situation, different required value for project. generally speaking, it would be less than 4 ohm. but some not strickly place it can be up to 200 ohm. you can ask your electric engineer for detail standard in your country.
If you find its not the value yoiu can pour some salt water on the ground. however its a complex engineering, have to deal with care.
Not sure exactly what information you need concerning "earth ground". CNPOWER, your #2 respondent basicly gave you the procedure for measuring ground conductivity as we do it in the broadcasting community. Commercial AM radio antennas (typically towers about 180' tall) are basically 1/4 vertical dipoles and depend on the virtual image signal in the ground plane for good propagation. The ground plane is typically 120 radials buried under the surface of the ground and the conductivity of the ground and the system is an important design parameter.
Sometimes measures must be taken to improve the ground conductivity (the saltwater, etc.) and the conductive interface between the copper radials and the earth. Any competent radio engineering firm will be able to give you more in-depth analysis. Suggest Hatfield Dawson Engineering in Seattle, WA. Hope this helps.
Yes there are specific procedures and purpose designed instruments for this task. The quality of earth grids must be measured for substation earth grids and SWER systems. Hioki and SEW both manufacture "Earth Meggers", try their sites.
The reference points are extra electrodes driven at specific distances from the grid or electrode. Some flash units even utilise current transformers and log the data via computer.
Resistance to Earth?
Re: Resistance to Earth?
