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 I 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?

  • 1
    You seem to be mixing two different things with the term grounding. One meaning for it is to connect the neutral to an electrode that you bury into ground to make your neutral to be at the same potential as the earth ground. The other meaning is providing safety ground, or protective earth, to your electrical devices, and it only means that the neutral wire is connected to ground wire at some point in the electrical system. Now which one are you talking about?
    – Justme
    May 10, 2020 at 20:54
  • @Justme What I mention in the whole question is safety ground, i.e, providing an alternative path for the current to flow to in case something goes wrong. Here it's not done in any of the ways you mentioned (and there are some federal norms about that, there is only one way you're allowed do it afaik). Power outlets here have 3 terminals, 1 neutral, 1 phase, both provided by the power company. The third is for grounding and is what I'm referring to. You use additional wiring that will connect the third terminal of every outlet in the house to metal rods buried into the ground. May 10, 2020 at 23:14
  • There are many ground resistance references on the web. Some are directly realted to your query. Here is an excellent manual by Megger. You do NOT have to have a fancy meter. Note that in some tests they convert their 4 terminal meter to a 2 terminal meter with straps. || The electrician's test is informal but probably good enough . He said " ... After that he's do the same test while connecting it to the phase/ground and see if the current matches. ". May 11, 2020 at 3:43
  • ... This works by seeing whether r\the ground and neutral return resistances to ground are similar. You cam make some assumptions and calculate the difference in neutral and ground resistances. You will see only small differences. The larger the load the easier to see the differences. || Electrodes. Find web references on how to make a good ground. Deep, Long pipes. Several pipes, Bentonite clay / Magnesium Sulphate / ... in hole . ... . || See Megger ref above p37-41 for improving earth. || Make ONE good ground and connect all to it. DO NOT make many smaller grounds. May 11, 2020 at 3:48
  • 1
    @EzequielBarbosa the latter is what I meant, providing safety ground to your electrical devices means the ground prong in your wall sockets. Look, the mains socket earth pin is not just connected to earth, otherwise there would be huge resistance from that pin to neutral and it would not protect you. It is connected to neutral, but only at one point in your electrical system, at your home or at substation or somewhere. Wall socket neutral and earth are and have to be at same potential and they have to have low resistance, so they are connected together somewhere.
    – Justme
    May 11, 2020 at 4:56


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