How I can trust the earth on the sockets?

[AlfBaz]

Yep. The labeling is a bit confusing so just to check, trip the one labeled light/main switch and see if you loose power on the outlets you want to use.

[themadhippy]

One design flaw of many of the plug in testers is they show a good circuit with only 2 of the 3 indicators lit.unless you  test the tester before and after every use you cant be 100% certain of the results.The better testers indicate all is good by illuminating all 3 indicators.Out of curiosity how many people test there volt meter before and after checking if a supply is safe to work on?

[AlfBaz]

Out of curiosity how many people test there volt meter before and after checking if a supply is safe to work on?

It depends on the level of sphincter contraction. The greater the contraction the greater the level of care

[wizard69]

The posting you referenced leaves a lot to be desired, in part it is garbage.

First the age of a building does impact its wiring, the ground and even if there is a ground installed.   The Safety of a buildings electrical system can easily be inspected and if you are concerned frankly you should learn to do the minimal yourself.

Second any ground can fail that is why testing and inspection make sense.   For example the original author claimed that driving a ground rod into the ground outside of the hose is a good solution.   It may be perfectly fine in one location and fail miserably in another.   Soil conditions weather and age all impact how well a driven ground rod will work.   Someplace on the net there was a rather elaborate write up on how to get those driven ground rods to work properly.   Likewise water pipes might not be ideal either as there has been a fairly large scale change to synthetic materials there.

In simple terms if grounding is important to you take the time to understand electrical systems and how to test those systems.   After all home wiring is just another form of electronics.  Highly regulated but not impossible to understand.   Ultimately if you are involved in electronics you will not want to rely upon others when it comes to safety.   

Can I please pm you both?

Nope.   Anything I have to say for free goes on the forum, where it gets peer reviewed and is available to all future readers.  I *REALLY* don't want to know any 'secret' that might make PMing me desirable to you, nor am I willing (or even qualified), to offer private paid electrical consultancy to an Australian resident.

Ed can speak for himself . . .

It's nothing like that, but I understand. This https://electronics.stackexchange.com/a/510070/207355 is where I got the information regarding trusting the earth on the socket. Do you think the answerer's fears are overblown? Reading their answer is what made me concerned.

[Mechatrommer]

One possible way without spending a fortune. Make a fixture with safety in mind and probe points. A properly rated 1M or 100k ohm resistor. Connect one end to earth wire, one end to hot live, measure potential of both end with dmm. If showing mains voltage level, there is current flowing, earth should be good. Earth potential will be the nominal mains voltage in your country, subtract with shown dmm reading.. if less than few volt, earth side is safe. Break or earth wiring impedance is within acceptable level.. but that depend on how stable the installation is. Ymmv.

[tkamiya]

I am a licensed electrician.  I've seen far too many cases of improperly wired ground that unless I did the work, I don't trust the outlet.  Typical multi-meter cannot be used to test an outlet.  Input impedance is way too high that "phantom voltage" (via magnetic and capacitive coupling) becomes a problem.  Fluke has a version specially made for electricians that has lower impedance.

A only reasonably sure way to test it is to go to a main distribution panel, and measure resistance between the grounding point and the ground prong.  Of course this should be done with someone with experience, and preferably a proper certification. 

Aside from that, your local home improvement center should have an outlet tester with few lights.  It will give you a reasonable assurance that it is connected properly (or not).  But does it grantee it?  I won't bet my life on it.

[Zero999]

As you are cleaning the leads, inspect them for any damage, and if you find even slightly nicked insulation or any cracks at all, they *MUST* be replaced before using that meter on any circuit above 50V.

That's fine if it's just your meter/test leads and you only use them at home, or in a situation where no one's going to use it on the mains, but I must stress you shouldn't take it to work like that. If someone else uses it on the mains and is injured, you will be liable. If I saw a some test leads in an unsafe condition where I work, I'd chop them up into pieces and put them in the scrap cable bin, even if they weren't mine! An unsafe meter would have its test leads, battery and fuse removed, the dial covered in duck/gaffer tape, a label attached stating it's unsafe and shouldn't be used and disposed of in the electronic recycling bin.

[Renate]

I'd chop them up into pieces and put them in the scrap cable bin.

That's right from a safety point, but it's also right from a sanity point.
If you have a VGA cable and one end is slightly wonky, chop the darn thing off so somebody else (or you) won't waste time with it.

[Ian.M]

Unfortunately its all too easy to damage good quality modern test leads - silicone insulation may be heat resistant but it is a lot softer and rips more easily than the old-fashioned PVC, and the probes and plugs are almost invariably moulded on so aren't rewirable. 

I must emphasise that Zero999 is right: Damaged leads *SHOULD* be cut up immediately in a workplace, makerspace, or formal educational environment,  but if one tells an impoverished maker hobbyist who's never going to go over the 30V from their bench PSU that, they'll probably laugh at you and ignore all your other advice.  If you do decide to risk keeping damaged test leads, *PLEASE* tag them 'Damaged: 50V MAX' and keep them in a locked draw to stop numpties killing them self with them!

I have bad memories of replacing plugs on VGA cables, in the days when monitors had wired in cables . . . .  It was always preferable to find a 'near enough' replacement cable from a scrap monitor and fiddle with the pin order of the PCB end till it matched, and transplant the cord grip rather than having to solder the center row of a DE-15 plug, then get everything to fit in a metal DE back shell!

[Mechatrommer]

If I saw a some test leads in an unsafe condition where I work, I'd chop them up into pieces and put them in the scrap cable bin, even if they weren't mine!

make sure you have replacement cable ready for them...

[Ian.M]

That idiot had better pray he never meets someone wearing the $3000 Shure KSE1500 electrostatic earbuds, as if he does, he's probably going to end up in A&E getting his nose reconstructed!

[Mechatrommer]

then this is more sane idiot... check 10:36, he wont cut anything equal or higher than the replacement cable...

at least these bunch of jobless filled the net to teach us what to do when we cut other peoples cable..

[Zero999]

If I saw a some test leads in an unsafe condition where I work, I'd chop them up into pieces and put them in the scrap cable bin, even if they weren't mine!

make sure you have replacement cable ready for them...

Funny video, but no, not for meter cables which I've destroyed because they were dangerous. They can thank me for saving their life and I'm pretty sure the company would buy a replacement, if they complained to a manager.

[Ed.Kloonk]

I was going to say cut something else off so they can't breed. Then I saw the flaw in my thinking in regards to who got the headphones cut the most.

 

[John B]

https://www.eevblog.com/forum/chat/girl-in-critical-condition-after-fault-earth-electric-shock/

I did have a re-read of this thread to get my head around the fault conditions. So for however unlikely the fault is, it's not unreasonable to give the house a thorough inspection to spot even slightly fishy readings.

Am I right in thinking the crux of the issue is a difference in potential between the "ground" wire circuit in the house and the actual physical earth? So all the metal appliances etc inside the house are connected with low resistance/impedance wire, but that circuit is bonded to the ground through an earth stake at minimum, and maybe some metal pipework, both of which have significant resistance to the ground?

[CatalinaWOW]

I'm going to add my voice to saying the link is overly alarmist.

I have observed each of the conditions described.  Starting with the dorms at my university.  But to my knowledge no one was killed or injured in spite of the hundreds or thousands of careless young people that cycled through them.  The reason is that two conditions are required to cause a hazard.  You need to have a moderate (few thousand ohm) connection to one of the wires.  And you need a similarly low resistance connection to ground.  The combination of two relatively unlikely events is very unlikely (though it does happen given the millions of people using electricity around the world.)  Normal life activities, including soldering with a wrist ground, rarely cause both of these conditions.

I agree with others that you can not prove that the wiring is totally correct or safe with simple multimeter or tester checks.  But you can easily check for an unusually high level of hazard simply by observing the voltage between ground and the neutral and hot wire.  Use old school safety tricks (one hand in pocket, one hand handles one probe at a time).  Think about the risks of sticking a probe into a socket and don't do it if you don't understand them and believe you have them under control.  If there is less than a volt between neutral and ground, and the nominal voltage is seen between neutral and hot and between ground and hot you are probably not at serious risk.  This simple test can give false positives which can be reduced by connecting an appropriate 30 kohm resistor between the multimeter inputs.  An additional check would be to measure voltage between the ground lead and earth potential, but as mentioned above earth potential is not easily found. 

Finally the suggestions in the attached link for correcting problems range from problematic to dangerously wrong.  If you find something that causes serious concern it is time to engage someone who knows what they are doing.

[pickle9000]

Just curious does Australia have gfci power bars? In Canada they are pretty common on worksites.

[Ian.M]

Yes.



From AlfBaz's Reply #21 above.

[JustMeHere]

Tools like this:
https://www.barefoothealing.com.au/p/australian-socket-tester/STAU

[Mechatrommer]

What is earth's potential is less important, (esp for high rise dwellers). Whats important is what is your feet's potential, thats what will decide kill or not kill. I've seen both floated neutral and gnd line and even got shocked from floated neutral. I've given enough thought about it and made the suggestion on my 1st reply.. and confirmed by some youtubes videos where people can touch KV safely if their feet as well.. though i'm not a certified electrician to be paid nor to give any credible advice. another cheap life saving device and light enough to bring anywhere anytime.. it uses your feet as decision maker.. so to get a valid reading, make sure your feet is wet enough (coupled with hot to gnd or hot to neutral test i mentioned, i believe this is how the 2 lights tester works). men are afraid of what they dont understand. Ymmv.



edit.. the one hand trick is not a guarantee to safety, if you get gripped the line with one hand, you can be dead as well, but the occurence of the one testing the line with their palm is very rare, but its not impossible.

[tszaboo]

Step 1: Buy a socket tester

Step 2: Test each sockets. Test the RDC, while not doing super important BIOS updates on your PC and ironing.
Step 3: Remove 1 typical socket, to take a look inside, on how the cables look like. If you see any wierdness, like aluminium cables, rotten isolation, dead mice, etc... then
Step 4: call an electrician. They charge you less money than doctors.

[SL4P]

If your socket tester indicates all is well, the simplest second test for me would be to measure resistance from the socket earth pin to a known metal water pipe that can physically be traced to physical ground.

Once you have a known good earth, you can test between others and that good one.
This can be done with power off to avoid any nasty existing wiring errors.

[Siwastaja]

Always GFCI aka RCD. No excuses in 2020.

Having working, properly done Protective Earth connections remove some risks, and add some others.

GFCI is a near-silver bullet that protects from both types of risks, without requiring earthing connection. The remaining risk types are very rare.

[rstofer]

You have used the same tester that a typical Building Inspector would use for approving an installation.

https://www.bunnings.com.au/deta-power-outlet-tester-plug_p4420488

Around here it would be similar to this:

https://www.amazon.com/Sperry-Instruments-GFI6302-Receptacle-Professional/dp/B000RUL2UU

I don't see worrying about made up possibilities posited on the Interwebs.  If you're worried about grounding, you're going to hate the BNC connectors on your scope.  They will be connected directly to earth ground.  So will that dangling alligator clip on the probe.

[tooki]

That youtuber should go to jail for having his meter in such horrible filthy condition. When i see things like this it will tell me a lot about the owner.

Out of curiosity, how does one go about cleaning such a device?

I can attest to the Fluke rubber holsters being safe to clean with dish liquid and warm water, as well as with isopropyl. Those two things will get off most grime. Neither one alone gets everything. I’ve been using those two to progressively wash every old Fluke 87 that comes across my desk at work. (It’s a training center, so it’s a pool of a couple of dozen meters.)