I'm Brazilian and I need to ground my house, especially because of some expensive equipment I don't want to use without proper protection.
By "grounding my house" I mean: provide an alternative path for current to flow to, in case of an electrical discharge or if the neutral provided by the power company breaks, for example. Here all power outlets have a third terminal for that purpose, and it's done by driving metal rods into the ground and connecting those terminals to these rods.
The thing is, I live in as small town and all the electricians around seem not to care for appropriately measuring grounding systems appropriately, by using a ground resistance meter. None of them even had one, and when I expressed my concerns about it (even though I'm admittedly a layman) they all dismissed it as something unimportant.
One of them told me ground resistance meters are expensive and that he'd test using a multimeter. If the voltage between ground and phase was the same as the one between phase and neutral, then it was ok.
Other would said he'd test it with a lamp. If the ground and phase could turn the lamp on, the grounding was good.
The other one (one whom I briefly worked with and the one I trust the most) was the only one who had a different attitude. He first asked me what kind of load I'd have on my system, what I planned to have connected. Then he told me I should have a separate electrical system for each of my showers (or other potent devices), each with individual grounding, and then all the least potent equipment could be connected to the main system, with one grounding for them all. But he also said he didn't have a ground resistance meter, but he'd tackle that by having 'three rods 3 to 5 meters away from each other providing the grounding' and that it should suffice.
So I tried looking into some other info in the internet and everything seems conflicting. The one guy who made the most sense for me was an electrician who told it is indispensable to have a proper meter, but that if you're an electrician and don't have one, there are some tests that are somewhat reliable you could make to make sure the grounding is good.
Basically he said one should disconnect all equipment from the outlets in the house, then do the multimeter test I mentioned before. After that, if the voltages were the same between phase/ground and phase/neutral, he'd connect some potent equipment (he used a drill machine) to phase/neutral and measure the current with an amperimeter. After that he's do the same test while connecting it to the phase/ground and see if the current matches. If those matched, the grounding was good.
I'm now left wondering, I absolutely need good grounding in my house, but the way it seems, I will either have to buy the ground meter – and they're expensive, especially considering ill use it only once – myself or go for one those fishy 'solutions' above.
What are your thoughts on it?
Best Answer
If the utility neutral breaks you're up against the ground (i.e earth, dirt, soil, water, rocks) being a relatively terrible conductor as compared to a metal wire, so the various tests involving testing the ground with a heavy load between hot and ground are highly dubious.
In the USA, the NEC (our local code, presumably not what applies in Brazil) requires either a ground test (time consuming, expensive meter) or two ground rods 8 feet or more apart, minimum. Many places have also implemented code requiring that in new construction the concrete foundation should include a "Ufer" ground or basically have the reinforcing steel tied into the grounding system, which is a far more effective connection to earth ground than ground rods in almost all soil conditions.
As a result, few electricians here bother to own the expensive meter, and most services have two (or more) ground rods 8 (or more) feet apart; Or one foundation ground (concrete encased electrode) and one ground rod.