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I just had (and solved thanks SE) a problem with a wall socket where the ground contacts were malfunctional. Much of the electrical safety relies on proper grounding. As far as I can read, details for state-of-the-art measurement of grounding is a science for itself, but the described methods seem far from impossible to do.

I want to test grounding of each socket (and possibly measure resistance for monitoring) as far as possible and practical for safety reasons (personal protection, possibly reduce noise (especially bad with telephone at my parents' house), and obvious prerequisite for surge protection).

Question: What are practical, safe and economic ways for a technically skilled person, but not regularly trained as electrician? E.g. 3 or 4 wire measurements with earthing, "measuring probe" and "helping-earth probe"? In particular, I am not specifically interested in one earthing metal pole but in the earthing as such that "arrives" at the sockets.

I live in an area with houses and small gardens, but with low distance to other houses/streets (5-50 m distance in all directions). So far, I could not figure out in what way my apartment house is (or: should be) grounded (no answer from landlord, I think they do not know themselves). Is it then necessary to disconect the earthing pole from the rest of the house as I read somewhere? (Seems that this was primarily meant only to test one specific earth pole independent from possibly other earthing poles)

I am willing to spend some money, but not necessarily hundreds of dollars/euros per household. I see devices (from cheap (24 €) to expensive (174 €), all still affordable) such as this, this, this and this. Price would be ok as I can use it for my family and friends as well, this is why I'd prefer DIY (if considered safe). Do such devices offer a valid approach to my question?

Disclaimer: All electrical engineering of the house was done by certified electricians (at least I hope so), and I do not want to change anything - unless I discover a problem and will then obviously ask a certified electrician to solve it if it requires work on the mains.

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Safest way would be with 1 of the 3 neon bulb testers,

Its pretty easy to read them to tell if they are mis-wired or you have a floating ground or neutral etc, e.g. you have a floating ground, the active to neutral one would be full brightness, and the other 2 would be quarter brightness

DO NOT DISCONNECT YOUR EARTHING POLE!!!! your ground may be fine, but your neighbors neutral may not, a few years back I measured about 7A flowing into my ground rod from a neighbours house.

Its also the correct thing to not trust the sparky, there was an outlet with active and ground flipped on the last place I stayed.

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  • \$\begingroup\$ Thanks! Seems that disconnecting ground pole was primarily meant only to test one specific earth pole independent from possibly other earthing poles, not what I need. A neon bulb tester (which 3?) would only indicate if ground is live (and be dark if real ground or disconnected)? Please correct me if I am wrong. What is a "sparly"? (could not find in dictionary or Google) \$\endgroup\$
    – Martin
    Sep 7 '19 at 12:46
  • \$\begingroup\$ sorry, sparky is an australian word for electrician. the 3 light testers (cannot suggest a specific one by this sites rules) show you any voltage difference between the 3 wires, a good socket will have Active-Neutral and Active-Ground fully lit, while your ground and neutral being bonded should have the Neutral-Ground off. If it is different from this, you have an issue. It would hide if the neutral and ground are reversed, but that is not an easy thing to test with a plug in tool. and if that light remains off, your reasonably safe, as they both get joined at the fuse box. \$\endgroup\$
    – Reroute
    Sep 7 '19 at 12:52
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These simple testers are easy to use and test more things than just the ground. Here's one on Amazon. Here's the Amazon search I used. They cost about $10usd, often less.

You just plug it in to each outlet and read the 3 lights.

Convert USD to EUR here.

So far, I could not figure out in what way my apartment house is (or: should be) grounded (no answer from landlord, I think they do not know themselves).

Older houses may not have a ground at all. My house was built in the 1950s. It has a ground from the main electrical box to the outside, but most of the wiring in the actual house does not have a ground. I specifically had to run a separate circuit for my computer which had a ground, because a surge protector (part of my UPS) requires a ground to work.

Is it then necessary to disconect the earthing pole from the rest of the house as I read somewhere?

Why would you do that? What is the purpose of this particular question? Did you hear you had to disconnect the ground pole from the main electrical box to test ground in the outlets?

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  • \$\begingroup\$ Seems that disconnecting ground was primarily meant only to test one specific earth pole independent from possibly other earthing poles, not what I need. \$\endgroup\$
    – Martin
    Sep 7 '19 at 12:48
  • \$\begingroup\$ Thanks. these devices you mention seem way more practical. Can I trust them, how do they work? Do they really measure proper earthing connection, as opposed to only "earth is not live"? Could you please expand a little bit on this issue? Acc. to manual even of one of the most expensive ones (Benning): "The socket tester cannot detect an inversion of the neutral conductor (N) and the protective conductor (PE)." \$\endgroup\$
    – Martin
    Sep 7 '19 at 13:00
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These instruments are very expensive. Usually you would need a licence and approved and calibrated instrument. If you want to DIY, you can buy a second hand instrument that is functional but it missed the calibration schedule, but it still costs hundreds of euros.

If you'r from UK you can search on ebay for: Metrel Alphatek Eurotest Instaltest Easi test

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