Jea48: I live in Santa Cruz, CA. I've called some local electricians, but so far I haven't invited anyone out yet because I want to research a little bit more.
Specifically, our house is on a hill that is a big rock. Dig down 8" and you hit this yellowish rock. This area used to be quarried for limestone. I think the type of geology is called "karst". The rock is not hard like granite, but it is hard enough that you need to chip at it with a pick to make any sort of hole.
The thing I'm wondering about is whether this rock (is it limestone?) has good grounding qualities. The local electricians I have called say they don't know and don't have the measurement tools to test, all they do is visually check compliance with local codes. Do you know if there is a lab somewhere I can send the rock for testing?
In my own visual inspection, I can see that we have just one ground rod, which appears to be just some rebar pounded into the ground; I don't know how deep it goes. The earthing strap is all corroded. So this definitely needs some attention!
Specifically, our house is on a hill that is a big rock. Dig down 8" and you hit this yellowish rock. This area used to be quarried for limestone. I think the type of geology is called "karst". The rock is not hard like granite, but it is hard enough that you need to chip at it with a pick to make any sort of hole.
The thing I'm wondering about is whether this rock (is it limestone?) has good grounding qualities. The local electricians I have called say they don't know and don't have the measurement tools to test, all they do is visually check compliance with local codes. Do you know if there is a lab somewhere I can send the rock for testing?
In my own visual inspection, I can see that we have just one ground rod, which appears to be just some rebar pounded into the ground; I don't know how deep it goes. The earthing strap is all corroded. So this definitely needs some attention!