Electrifying sensation whilst soldering with ESD wrist strap

[alm]

Lets see, you are saying, measure phase relative to earth ground and phase relative to neutral? If these measurements are equal, it indicates that I have found earth ground wire?

Measure the voltage from phase relative to neutral, and from neutral relative to earth. The sum of these two should be equal to the voltage of phase relative to earth. Note that this only shows that the yellow-green wire is connected to ground somehow, not that the impedance is low enough to quickly trip circuit breakers/fuses.

I would probably get an electrician to verify the ground connection. They should have the training and equipment to measure earth bond resistance.

[SeanB]

Copper coated steel rod ( electrical wholesalers, ask for earthing rod and clamp) and hammer into ground, water well with water and a little salt ( gets resistance down if the ground is rocky) and leave overnight. Measure AC volts first between the ground rod and line, neutral and the PE connection, using a long length of copper wire to bring the connection from the outside to near to the socket.  you should get 220V or so between the live and the rod, around under 10V between the neutral and the rod, and hopefully lower between the earth connection and the rod. If you get that then you can consider measuring earth resistance, but not with a normal multimeter. You need a Ground loop tester, which you can probably hire for the day. Normal multimeters will probably not like the noise present on the wiring.

If this shows there is no earth then call the owner ( if renting) or an electrician to bring the house up to code. Minimum is to bond all sockets to earth, mains earth rod set and compliance certificate. Better to add at same time circuit breakers, and earth leakage on all socket outlets. This will make things safer, and will show up all the degraded insulation by having the earth leakage doing random tripping, so all wiring will have to have in-situ insulation testing done, and all that fails will have to be replaced.

[touchh]

I had a similar problem, Work bench top was metal with ESD mat over 50% of it, then I also noticed 50v on the oscilloscope one day, when the probe was touching the work bench. That's when I really had a shitfit amazed that something had not been blown up, be it the scope, the PSU or any project that accidentally touches the workbench.

Found out that it was a combination of a non-isolated power supply and stray inductance from all the 120v power cables on my work bench giving my workbench 50v to ground, with almost no current. simple fix for me was grounding the entire workbench to mains ground.

[Spawn]

... otherwise if you have central heating or something that goes into the ground eventually you could improvise a ground wire by typing the end to an exposed part of the metal pipes. But this later part is not safe.

For the time being use maruish’s method here, just find a point where you can measure between the phase (L) brown wire and the central heating pipe you will be measuring something close to the normal voltage in your home. Brown wire might be some other color because your installation is old and was build before new EU regulations, in that case look for red and gray wire, red should be phase.

Back when I started work we did a lot old houses with this method, getting your earth from water lines or heating installations, later on new regulations didn’t allow this.

But make sure like SeanB said to get a propper earth line, there are several methods for this.

[Janne]

If you start changing electrical sockets into the grounded type, you really should change all of the sockets in a space at one go. Mixing grounded and un-grounded sockets in the same space is dangerous.

If you have a room full of non-grounded sockets.. Ok, if one of your appliances faults, and the cover of the device becames live (115V, 230V or whatever), you will probably get a mild shock. Not too dangerous, because the insulation of the space is good. But, at the moment you add one grounded socket the situation became much more dangerous. Now you have some appliances, which are hard grounded, and some other devices, which rely on ground insulation to work safely in a fault situation.. Touch a grounded device + a faulty ungrounded one, and it might get fatal!

That's why i would recommend against using any water pipe grounded configurations or grounded extension cords around un-grounded sockets. Just bite the bullet, and have proper grounded sockets installed.

[king.oslo]

Thanks Janne,

I will follow this advice.

Alm, I measured between live and gnd: 132.7V, between neutral and gnd: 126.5V. 132.7V + 126.5V = 259.2V.  Between live and neutral 226.3V. What do you think?

Marius

[alm]

This is either some weird earthing system or most likely the green/yellow wire is not connected to earth at all. The fact that the voltages don't add up to ~226 V indicates that the yellow/green wire is most likely floating and only capacitively coupled to the electrical distribution system. This is where low-impedance voltmeters are much more useful.

The voltage between phase and neutral should be less than the voltage between phase and ground, since the current flowing through the neutral is causing a voltage drop (IR drop).

[king.oslo]

I measure between my waterpipe and the green/yellow wire behind faceplate 0.8ohms +- 0.1ohm with my HP 3456A on 2wire resistance mode.

What do you think of that?M

[siliconmix]

Hello my friends,

Lately I have been feeling current flowing through my body whilst soldering using my ESD strap. The experience is not shocking, but it is enough to make me stop soldering, to take the strap off.

I probed my board, solder and iron relative to ground potential, but I could not find AC or DC above 4V anywhere using a averaging handheld DMM, true RMS 6.5digit DMM or oscilloscope. Except when I measured the soldering iron with the true RMS meter. It saw 55VAC relative to ground. But when I went to probe it with the oscilloscope, I found nothing. Could my DMM be lying? Or is it likely that it went low before I came to probe it with my scope? Now I am not sure where else to look for the source.

I want to find and eliminate the source. It worries me a bit to think there may be a hazard somewhere on my bench.

What are your thoughts?

Kind regards,
Marius

do you actually hold the solder or use dispensing tube or on plastic bobbin.? is your soldering iron connected to a transformer or straight to mains.? i have felt this where we used to live but since moving house no problems.i thought i was going crazy.i couldn't work out wether it was hot flux splashing up on my forearms or current.transformer coupled soldering iron best for you and for sensitive ic's me thinks

[IanB]

In response to the previous few posts in this thread, attempting electrical work in the home if you are not an expert is potentially dangerous. There are a few no doubt well meaning posts above suggesting home brew solutions made by people who perhaps know what they are doing. But suggesting such a course of action to someone who does not have the prior knowledge, training and skills to do such work is utterly horrifying 

Please, don't fiddle with this stuff, call an electrician. Even call the electricity company. In most countries they will do a free safety check for you and give you advice about what might need fixing.

For starters, if the voltage between neutral and the yellow/green wire is 126 V, then that is not a proper earth wire and you should not trust it. Stop here and get expert advice.

[alm]

I measure between my waterpipe and the green/yellow wire behind faceplate 0.8ohms +- 0.1ohm with my HP 3456A on 2wire resistance mode.

What do you think of that?M

This most likely means that the water pipe and green/yellow wire are both connected to the same point, which is not connected to PE. I second IanB's suggestion to get a professional to at least identify the problems with this installation. If the earth wires are not even connected, who knows what else might be wrong.

[Spawn]

Please, don't fiddle with this stuff, call an electrician. Even call the electricity company. In most countries they will do a free safety check for you and give you advice about what might need fixing.

Actually you are totally right about that IanB, after so many years it gets easier to give advice to people while I have to do safety exams for NEN3140 (Dutch norms) each two years because of the position I have in the company I work.

Suddenly I feel like this guy below, while I was the one who posted the message to him telling to stop posting things like that… He didn’t approve my post first week after that he allowed to be shown and ask for thumbs up for what he wrote 

[IanB]

I'm going round my house right now replacing the old and worn electrical sockets with new ones. Including examining the ones that were previously replaced by some previous owner. Oh my! The horrors I have found. The originally installed ones were installed to a low standard by the builder, but were basically sound. However some of the previous home owner's work has been terrible. I have found ground wires loose on the screw terminal, and last night I found a "pigtail" holding together by a whisper and a prayer. The original 12 gauge wires were too big to push into the "push fit" connectors on the socket (a plague upon those), so some 16 gauge wires (too thin) had been made into pigtails. For a pigtail you are supposed to twist the two wire ends together with pliers and then screw a correctly sized wire nut over the end to insulate it. In this case there was no twisting and an incorrectly sized wire nut was all that held the two wires in contact with each other. There was a fire waiting to happen if a heavy load had been put on the socket. All because someone couldn't bend the 12 gauge wire and fasten it to the screw terminal.

In the context of this thread, I have posted previously how one of my sockets has a poor ground connection (it measures tens of volts higher than neutral). My socket tester highlights this fault and that's how I knew something was wrong. I am partly inclined to do the light bulb test in that video. It would at least tell me if the ground is connected or floating. Although ultimately I have to trace it back and find the fault.

[G7PSK]

The light bulb is of not much use if you have ELCB's they will just trip, mind you that tests them.

[Spawn]

I dont know about the regulations on other countrys, but light bulb is not a test tool at al, simple as that 

[IanB]

I dont know about the regulations on other countrys, but light bulb is not a test tool at al, simple as that 

It may not be an official test tool, or even an analytic test tool, but it is a test tool.

If I connect a light bulb between live and earth (or hot and ground) and it lights as brightly as between live and neutral, then I have very strong support for the hypothesis that the earth connection has a low resistance return path. Since I am especially interested in the protective earth conducting sufficient current to blow a fuse in the event of a fault, this is not a bad test for that hypothesis.

[Spawn]

I am not with you there,  it is dangerous to test like that, specially showing that on youtube if it’s like the best option to test your ground protection.

Besides I am not sure about other EU countries but in the Netherlands you can’t even test like that because we have earth leakage circuit breakers in our installations, the moment you put your lamp between live and earth the circuit gets shut off. You can’t even test with old fashion Duspols because they draw to much current. With a Earth leakage circuit braker anything above 0.03A leaking to earth will shut your circuit. In some places it is litle higher with 0.05A

Earth leakage circuit breaker:

[IanB]

Newer installations tend to have whole house ELCBs (GFCIs in the USA), but plenty of existing homes do not. You are right of course that this test would fail in cases where such protection exists. I am assuming I would wire up a proper test with a plug and not use bare wires as shown in the video.

[G7PSK]

A light bulb can be quite a good test in some conditions, I have seen people tear a car apart looking for a mystery fault, and replace parts as faulty, They have tested the wiring with a DMM and got a good reading on voltage but still the item will not work.
If they had used a light bulb and you can buy testers which are a 21 watt light bulb they would have found that they had either an earth or feed fault of high resistance stopping the correct power flowing.

ELCB's introduce quite a high resistance into the earth line raising the whole house potential compared to a direct earthing.
In my house even the walls measure 192 volt with a DMM to direct ground. I can measure a voltage but no current as my DMM is not sensitive enough I need one of Dave's micro current thingy's. The problem I found is this renders the house socket earth pin useless for a radio earthing so I had to build one. A six foot stainless steel rod (copper corrodes) in a hole that is filled a mix of soil and rock salt.

[electroguy]

ELCB's introduce quite a high resistance into the earth line raising the whole house potential compared to a direct earthing.
In my house even the walls measure 192 volt with a DMM to direct ground. I can measure a voltage but no current as my DMM is not sensitive enough I need one of Dave's micro current thingy's. The problem I found is this renders the house socket earth pin useless for a radio earthing so I had to build one. A six foot stainless steel rod (copper corrodes) in a hole that is filled a mix of soil and rock salt.

how do ELCB's introduce resistance? they don't even use the earth line! Your earth should still be direct earthing. What voltage do you get between your earth and active? I think you should get an electrician to check your ELCB or get you a new one, they are cheap these days... Do you have a photo we can see? maybe we can have a look at your setup?

[G7PSK]

Been checked by an electrician. They have a coil in the earth as well as the lines.

[Rerouter]

must have been quite a coil, some of the more questionable sparkies still coil up any slack they have, but normally its shouldnt cause anything quite like your describing,

[king.oslo]

IanB, I think if you want to check the resistance of the grounding, how about a jumper between line and earth, then turn on the power, and watch the fuse or circuitbreaker blow?M

[electroguy]

Been checked by an electrician. They have a coil in the earth as well as the lines.

maybe you have one of the old voltage sensing ELCB's. How old is it just out of curiosity? Is it over 20 years old?
Get rid of it, and get it swapped to the new ones.
Can you show us a photo of the ELCB you are referring to?

[Monkeh]

IanB, I think if you want to check the resistance of the grounding, how about a jumper between line and earth, then turn on the power, and watch the fuse or circuitbreaker blow?M

There are devices (earth fault loop impedance testers) which do this in an accurate manner without inviting a multiple-kiloamp fault current.

Been checked by an electrician. They have a coil in the earth as well as the lines.

An RCD has no connection to earth and an RCBO only a functional (not protective, and not part of the final circuit) earth. An ELCB is an old, and often dangerous device which is unsafe to continue using in most cases.