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## Re: [TowerTalk] Soil resistivity test done: Some questions

 To: towertalk@contesting.com Re: [TowerTalk] Soil resistivity test done: Some questions Beat Meier Sat, 09 Sep 2006 17:28:38 -0300
 ```Beat Meier wrote: Hi again Now I really don't understand anything. Today after raining 2 days I have mesaured again the resistivity (now 107ohm thats ok) and my ground in my house (3 pole method). The ground in my house is show as 9.47 ohm. As I wrote earlier I have only 2 2.5m 5/8 ground roads and the resistivityis 500ohm respectivly 120ohm. How can this be apart from doing something wrong? Beat >Hi all > >I'm still a grounding dumy but I've just bought a GEO test and have done >some soil resistivity test >(for just 800US\$ I can do 4 pole methods, cheapest I have found and >still has serial port >to colect data ...) >I'm still in putting my new tower of 200ft ... > >Now I have some questions. >In a place where I have 2 ground roads (each 2.5m) I have a resistivity >of 120. >4m away I have a resistivity of 500. >The test was done with the 4 pole method. >I have not measured the ground of the house, only the soil just above >where the >roads are with several depth and in the deps of 3 m I have this 120 > >Now my questions: > >1. This low resistivity comes from the 2 ground roads already there >I have read that 2 ground roads in parallel will half the resistivity >i..e 500/2 250 but I have 120 >If you use 4 you get Resistividad/4 i.e. 500/4=125 >Is this formula right? >The other idea is that the fundament of the house is very near (about >1m) could this also >have such influence to lower the resistivity because of concret?? > >2. The resistivity of 500 is not very good, isn't it? > >I have calculated that you must put 36 ground roads in parallel to >achive a resitance of 13.8 >which is still pretty bad (of course only if the formula above is right) > >BTW: The tests have showed what someone already told me that the soil >here is not good >to go in depth ... I have the following: > >a=2m -> 486 >a=3m -> 546 >a=4M ->535 >a=6m -> 429 > >so it seems that going in deep does not make any difference (apart from >the cables you must use >to connect the ground roads) in contrast to use parallel ground roads. > >And last question: >How many copper have good ground roads. The ground roads I can buy here >have only 200um of copper >(5/8''-2m or 5/8''-3m). I have seen that they peel quickly if driven >into earth and there is any obstacle ... > >What I can get also is plate of copper 30cmx30cm but this costs about 8 >times more than one ground road >I don't know how they lower the resistividad of the soil ... I have read >in an article about >0.8*Resitivida/circumference is this right? > >What about putting using the fundament of the house i.e. drive a whole >in the concrete and connect a >copper or what ever cable ot the iron and put again concret? > >Thanks for any ideas or comments > >Beat >_______________________________________________ > > > >_______________________________________________ >TowerTalk mailing list >TowerTalk@contesting.com >http://lists.contesting.com/mailman/listinfo/towertalk > > > > _______________________________________________ _______________________________________________ TowerTalk mailing list TowerTalk@contesting.com http://lists.contesting.com/mailman/listinfo/towertalk ```
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