Electrifying sensation whilst soldering with ESD wrist strap - Page 1
Forum section: electronics / general

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 12:26:12 pm
content: 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

author: Unknown
author_rank: Unknown
timestamp: March 24, 2012, 12:33:06 pm
content: What is the resistance between the ESD strap and ground? This should be at least 1 Mohm, so currents should not create any sensation. I would check the grounding of your mains sockets, wrist strap and soldering iron. If there is current flowing through the wrist strap, there must be a relatively large potential across it compared to the resistance. 4 V across 1 Mohm does not create a tingling sensation. I would fix both the potential and the wrist strap resistance.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 12:33:59 pm
content: Wrist strap resistance is 1M. I will go sit in the electric chair and tell you the potential across it whilst soldering. Please just give me a minute. I am not looking forward to itElectrical appliances where i live, unfortunatly does not have ground in this building. I am using a cold water pipe for ESD GND.M

author: Psi
author_rank: Super Contributor
timestamp: March 24, 2012, 12:40:42 pm
content: If your wrist strap has 1Meg to ground then it isn't part of the circuit responsible for the sensation.Unless you have leakage from the 11kV mains line somehow, but that is extremely unlikely.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 12:51:52 pm
content: alm, Psi, I went back to the electric chair to solder like normal. Now I get no tingling sensation. Damn.Psi, could you be wrong? Once I took the wrist strap off, I felt nothing, when I put it back on, the sensation was back. I did this just to be sure it was the strap. I understand that 1M + resistance of skin = high resistance, but there is no doubt that current was flowing, and disappeared once I took the strap off.Kind regards,Marius

author: Ajahn Lambda
author_rank: Regular Contributor
timestamp: March 24, 2012, 12:55:46 pm
content: Strange question, but are you wearing good shoes? And are you working on a concrete floor?Don't laugh, I've got an old non-isolated amplifier that will give you a nasty tingle when you're touching the strings of an attached electric guitar, given those situations. My feet became the ground connection, on a concrete floor with a small amount of moisture (it was a basement).

author: T4P
author_rank: Super Contributor
timestamp: March 24, 2012, 12:57:06 pm
content: Does your iron have a earth pin ? you'd better have one on your iron .

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 12:59:46 pm
content: Quote from: Dave.S on March 24, 2012, 12:57:06 pmAt the minute, it doesn't.Quote from: SigEpBlue on March 24, 2012, 12:55:46 pmI am sitting on a rubber mat with wool socks.M

author: SoftwareSamurai
author_rank: Regular Contributor
timestamp: March 24, 2012, 01:53:21 pm
content: If your wrist strap-to-ground has a solid 1M of resistance, you're probably not feeling a DC current. But itispossible that you're feeling an induced AC flow. If your soldering iron isn't properly grounded, it could, with just the right conditions, cause an AC feedback loop to form between it, you, and the surrounding environment. Sitting on a rubber mat with wool socks insulates you from earth ground extremely well, so your wrist strap is the only ground potential for the AC to couple to, hence why you feel it only when you have it on. If this is the case, hunting down the source is going to be like chasing a ghost, since doing such seemingly non-important things like moving your chair over an inch might disturb the feedback loop just enough to break it.Having said that, I would take a closer look at your soldering station and the power supply to make absolutely sure there isn't an intermittent short somewhere, just to be safe. And make sure it's properly grounded. Most of the time these mysterious tingles are due to equipment that has a floating ground while powered by AC.

author: ejeffrey
author_rank: Super Contributor
timestamp: March 24, 2012, 03:30:07 pm
content: Quote from: king.oslo on March 24, 2012, 12:59:46 pmYou mean it is designed to be earthed but you have defeated that somehow? Try fixing that...

author: G7PSK
author_rank: Super Contributor
timestamp: March 24, 2012, 04:09:10 pm
content: You say that the earth is via a water pipe, has any repairs to the water supply taken place, like a new piece of plastic pipe inserted, also if your soldering iron is meant to be earthed and is not due to no or poor earth on the system that could well be your problem you say that there is 55 volts on the earth side of your iron relative to to your earth on the wrist strap this will give you a tingle even with the 1M ohm in the strap if as is quite likely the metal contact of the wrist strap is placed over a nerve, The other thing is it might not be electrical problem I used to get tingles in the wrists when working, it was the first sign of carpal tunnel syndrome, it started low and slow and increased until i had to go and see a doctor, ended up having surgery to fix the problem.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 04:09:28 pm
content: Quote from: ejeffrey on March 24, 2012, 03:30:07 pmSorry, I can see that what I wrote was incomplete- The soldering station has earth contacts on the socket, but the building I am in does not have a lead going off to earth.M

author: Unknown
author_rank: Unknown
timestamp: March 24, 2012, 04:35:46 pm
content: If a piece of equipment has an earth contact, it is designed to be used with an earthed socket, using it without earth connection defeats its safety features. A single fault (eg. loose wire) could shock you, something that would require a double fault (much less likely) if an earth connection was in place. It's quite likely that there is some leakage current going through the mains input filter which is supposed to flow through the earth pin, but is now flowing through your body when it has a low impedance connection to earth.A water pipe is not a solid earth connection, and earthing via the water pipe is not even allowed in many countries. As already stated, water pipes are routinely replaced with plastic pipes, and it's not very nice for the plumber to get shocked because something you 'earthed' via the water pipe has a fault.

author: Monkeh
author_rank: Super Contributor
timestamp: March 24, 2012, 04:41:03 pm
content: Quote from: king.oslo on March 24, 2012, 04:09:28 pmYou should get that fixed. It can't possibly meet regulations.

author: T4P
author_rank: Super Contributor
timestamp: March 24, 2012, 05:24:16 pm
content: You need a earth pin in your home mains .If not you are just gonna blow things up with ESD by accident with your ironNo actually the most important thing is that something doesn't accidentally short out to the metal body in your iron .

author: IanB
author_rank: Super Contributor
timestamp: March 24, 2012, 05:48:32 pm
content: Quote from: king.oslo on March 24, 2012, 04:09:28 pmAre you saying that all of the electrical sockets in your building look like this one?http://electricaloutlet.org/type-cAnd that none of them look like this one?http://electricaloutlet.org/type-fIf so that is rather unfortunate. It means you cannot safely buy or use any appliance that has an earthed Schuko type plug, including your soldering station.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 06:01:10 pm
content: IanB, that is true. I am thinking about running a wire off to earth ground.M

author: mariush
author_rank: Super Contributor
timestamp: March 24, 2012, 06:10:00 pm
content: You should have at least one socket with ground in the house. Usually you find such sockets near the bathroom, as were meant for washing machines or hair driers.You should have ground wire through the sockets - unless you house is really, really old. Try opening the faceplate of a socket, maybe you actually have the cable there but it's not connected to anything.If you find the grounded socket, just use long power strip... 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.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 24, 2012, 06:27:13 pm
content: Quote from: mariush on March 24, 2012, 06:10:00 pmWow! You are right. Under the faceplates I found the good old green/yellow wire. How do I measure whether it actually goes off to mains ground? Measure the voltage between phase and ground? The fact that the faceplates was the C-type, makes me worry about this.The house is 70 yrs old.Kind regards,Marius

author: IanB
author_rank: Super Contributor
timestamp: March 24, 2012, 07:11:03 pm
content: Quote from: king.oslo on March 24, 2012, 06:27:13 pmGo and have a look in the cupboard where the circuit breakers are. If you can see big green and yellow wires in there bonded to metal pipes or other objects it is likely the building has been rewired recently to modern standards, especially if you find circuit breakers and not fuses. If there is evidence of proper earthing arrangements where the circuit breakers are then the green and yellow wire behind the socket is almost certainly a proper earth. If so you could replace type C sockets with type F sockets and get proper grounding.Is the building yours or does it belong to someone else? If there is a landlord you will have to ask the landlord to have the sockets modified.

author: Unknown
author_rank: Unknown
timestamp: March 24, 2012, 07:37:08 pm
content: A neat trick I once picked up from a Fluke appnote is to measure the voltage between phase, neutral and earth. Only consider these measurements if you have the equipment, experience and confidence to measure live mains wires. Neutral and earth are generally bonded somewhere, but the current flowing through the neutral wire causes and IR drop compared to the earth wire, through which no current is flowing. You're using the earth wire as a sense connection to the earthing point. The voltage between neutral and ground plus the voltage between neutral and phase should be the same as the voltage between ground and phase. This allows you to quickly verify correct wiring. It's not a replacement for proper earth bond resistance and insulation resistance tests, but it should give you a clue whether it's connected to PE or just a loose wire (the latter would be against the code in many countries).

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 25, 2012, 01:17:27 am
content: Quote from: alm on March 24, 2012, 07:37:08 pmLets 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?Quote from: IanB on March 24, 2012, 07:11:03 pmI will check this tomorrow. Thanks.M

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 28, 2012, 02:28:09 pm
content: Alm, did I understand your neat trick?IanB, the cupboard holds old fashioned fuses. No modern circuit breakers. I could spot some green and yellow wire in there. The wires went off into some pipes to somewhere else. No idea where.What do you guys think? Is this good earth ground?M

author: G7PSK
author_rank: Super Contributor
timestamp: March 28, 2012, 02:51:37 pm
content: Most likely not, as you appear to have grounding problems. You need to find a good ground and test for resistance and potential between the good ground and the wiring ground that you have.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 28, 2012, 06:23:10 pm
content: Quote from: G7PSK on March 28, 2012, 02:51:37 pmShould I hammer a copper stick into the ground and measure the resistance between this and the green and yellow wires behind the faceplates?M

author: Unknown
author_rank: Unknown
timestamp: March 28, 2012, 06:41:20 pm
content: Quote from: king.oslo on March 25, 2012, 01:17:27 amMeasure 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.

author: SeanB
author_rank: Super Contributor
timestamp: March 28, 2012, 06:49:53 pm
content: 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.

author: touchh
author_rank: Contributor
timestamp: March 28, 2012, 07:02:52 pm
content: 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.

author: Spawn
author_rank: Frequent Contributor
timestamp: March 28, 2012, 07:06:45 pm
content: Quote from: mariush on March 24, 2012, 06:10:00 pmFor 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.

author: Janne
author_rank: Contributor
timestamp: March 28, 2012, 07:34:38 pm
content: 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.

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 28, 2012, 08:16:24 pm
content: 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

author: Unknown
author_rank: Unknown
timestamp: March 28, 2012, 08:24:46 pm
content: 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).

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 28, 2012, 08:37:44 pm
content: 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

author: siliconmix
author_rank: Frequent Contributor
timestamp: March 28, 2012, 08:40:51 pm
content: Quote from: king.oslo on March 24, 2012, 12:26:12 pmdo 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

author: IanB
author_rank: Super Contributor
timestamp: March 28, 2012, 08:45:01 pm
content: 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 horrifyingPlease, 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.

author: Unknown
author_rank: Unknown
timestamp: March 28, 2012, 09:00:20 pm
content: Quote from: king.oslo on March 28, 2012, 08:37:44 pmThis 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.

author: Spawn
author_rank: Frequent Contributor
timestamp: March 28, 2012, 09:11:18 pm
content: Quote from: IanB on March 28, 2012, 08:45:01 pmActually 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

author: IanB
author_rank: Super Contributor
timestamp: March 28, 2012, 09:31:27 pm
content: 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.

author: G7PSK
author_rank: Super Contributor
timestamp: March 29, 2012, 12:08:51 pm
content: The light bulb is of not much use if you have ELCB's they will just trip, mind you that tests them.

author: Spawn
author_rank: Frequent Contributor
timestamp: March 29, 2012, 10:23:32 pm
content: I dont know about the regulations on other countrys, but light bulb is not a test tool at al, simple as that

author: IanB
author_rank: Super Contributor
timestamp: March 30, 2012, 12:43:32 am
content: Quote from: Spawn on March 29, 2012, 10:23:32 pmIt may not be anofficialtest 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.

author: Spawn
author_rank: Frequent Contributor
timestamp: March 30, 2012, 02:21:09 am
content: 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 0.05AEarth leakage circuit breaker:

author: IanB
author_rank: Super Contributor
timestamp: March 30, 2012, 03:40:33 am
content: 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.

author: G7PSK
author_rank: Super Contributor
timestamp: March 30, 2012, 07:55:15 am
content: 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.

author: electroguy
author_rank: Regular Contributor
timestamp: March 30, 2012, 09:25:31 am
content: Quote from: G7PSK on March 30, 2012, 07:55:15 amhow 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?

author: G7PSK
author_rank: Super Contributor
timestamp: March 30, 2012, 09:42:44 am
content: Been checked by an electrician. They have a coil in the earth as well as the lines.

author: Rerouter
author_rank: Super Contributor
timestamp: March 30, 2012, 09:50:48 am
content: 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,

author: king.oslo
author_rank: Frequent Contributor
timestamp: March 30, 2012, 10:24:56 am
content: 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

author: electroguy
author_rank: Regular Contributor
timestamp: March 30, 2012, 10:32:24 am
content: Quote from: G7PSK on March 30, 2012, 09:42:44 ammaybe 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?

author: Monkeh
author_rank: Super Contributor
timestamp: March 30, 2012, 12:11:00 pm
content: Quote from: king.oslo on March 30, 2012, 10:24:56 amThere are devices (earth fault loop impedance testers) which do this in an accurate manner without inviting a multiple-kiloamp fault current.Quote from: G7PSK on March 30, 2012, 09:42:44 amAn 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.

author: electroguy
author_rank: Regular Contributor
timestamp: March 30, 2012, 12:26:13 pm
content: Quote from: Monkeh on March 30, 2012, 12:11:00 pmThank you, the words i was looking for! As Monkeh mentioned, the ELCB does not protect your body effectively. On the other hand, an RCD gives body protection and in most cases can save your life (not all cases, but most).

author: T4P
author_rank: Super Contributor
timestamp: March 30, 2012, 05:33:56 pm
content: Do all RCD's have a Test button ?I have no idea whether mine's a RCD or ELCB i but think it probably is a RCD since this building was constructed in the 1970's . ( But it looks very old and very flimsy now )It is so sensitive that when something goes even slightly wrong ( like a open circuit tungsten bulb ) it just TRIPS !Well there was this once that a tungsten bulb ( don't know why they still exist in my house )filament was touching the glass ( shouldn't it be OKAY ? )and when switched it glowed WHITE for a few miliseconds before all the breakers tripped . ( Right , the incoming service 100amps MCCB , unchecked "neutral line" , unchecked RCD and the 13amps MCB of course . )

author: Monkeh
author_rank: Super Contributor
timestamp: March 30, 2012, 08:16:47 pm
content: An RCD will not trip from a bulb blowing. It cannot.

author: T4P
author_rank: Super Contributor
timestamp: March 31, 2012, 12:40:58 am
content: Quote from: Monkeh on March 30, 2012, 08:16:47 pmBut mine did . I have no idea why it did .

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 12:47:29 am
content: Quote from: Dave.S on March 31, 2012, 12:40:58 amUnless that bulb is in an earthed enclosure, shattered, and the filament fell on the enclosure, there's no way a real RCD (an ELCB might behave differently.. we don't use them now.) could trip.

author: electroguy
author_rank: Regular Contributor
timestamp: March 31, 2012, 06:35:32 am
content: Quote from: Monkeh on March 31, 2012, 12:47:29 amMaybe there was a short circuit, so the current exceeded the RCD and it tripped (ie: it tripped because of current, not because of an earth leakage...)

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2012, 09:39:11 am
content: RCD's do trip with a very large current flow, as they are not wound perfectly, but have a very slight imbalance, and the high current ( well above the rated carry current, but well within the must break fault current) generates enough sense current to trip them. think of this being an extra safety feature, as it ensures a fault will both trip the overcurrent breaker, but will also ensure the system has the capacity to break the fault if the fault is too large for the overcurrent device ( can be if the fault is within 3m of the breaker, as there is a built in assumption that there will be no faults within 3m of the breaker, and the rating is sized so) the extra contacts will help break the arc.Earth leakage breakers are not easily found, as they were pretty much only used in industrial applications, almost never domestic use. They were used only if the supply could be isolated from ground and made to float at a defined potential to enable faults to be detected by current flow. Mostly used still on medical isolated supplies, with 1 transformer and monitor per outlet socket.If the earth and the piping is well bonded, but is floating, then you need to call the supply authority, as they have a broken earthing point in their system that feeds your house, and they need to fix it. The 3 wire power system in the house ( Line, Neutral and Protective Earth) is made from a PME system on the pole supply where there is a Live ( 1 of 3 phases) and an earthed neutral wire, which is provided to the customer side by joining the customer neutral and earth together, and providing an extra earth connection direct to ground at the customer premises. All this is on the supply side before the meter, and is the suppliers responsibility. Most common fault is a corroded ground rod, or a broken earth wire from a massive fault. ( earth wire is allowed to be a certain amount smaller, and if it corrodes a lot it can be blown open by a short) Call the supply authority.

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 03:21:53 pm
content: RCDs are not designed to trip under overcurrent situations and the chances of them doing so are pretty slim..

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 04:12:20 pm
content: Quote from: Monkeh on March 31, 2012, 03:21:53 pmIf a combined RCD/circuit breaker is installed as primary protection in place of a normal circuit breaker then it will have the function both of RCD and over current protection in one device. Under these circumstances it could trip in the event of a blown bulb. The (normal) circuit breakers in my house here in the US do tend to trip when a bulb blows.

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 04:22:06 pm
content: Quote from: IanB on March 31, 2012, 04:12:20 pmIn which case it's a: Not an RCD, and b: Totally pointless because he has a 100A MCCB (according to him, anyway).As for your breakers tripping, that's because the American idea of a CPD is very poorly thought out.

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 04:39:00 pm
content: Quote from: Monkeh on March 31, 2012, 04:22:06 pmI can appreciate that electrical standards vary between countries, but what is wrong with putting an RCD in the same enclosure as a circuit breaker? That is what they do, for example, with AFCIs.Also, what is wrong with a breaker tripping when an excess fault current from a blowing bulb is present? Are you suggesting the breaker should react more slowly?

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 04:48:44 pm
content: Quote from: IanB on March 31, 2012, 04:39:00 pmI didn't say it's wrong, I said it's not an RCD. And it's totally pointless because he already has a protective device for the installation (The MCCB) and the circuit (the MCB). You do NOT add extras for fun, it's bad design.QuoteYes, it should react more slowly, and it would if their breakers didn't have a silly tripping profile which prevents a 15A device operating on a 15A breaker.

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 05:03:48 pm
content: Quote from: Monkeh on March 31, 2012, 04:48:44 pmWe don't really know anything about what Dave.S has. Most of what he writes is confused or speculation or wrong or just plain garbage.Here in the US there is a main circuit breaker for the installation (e.g. 100 A), and then each individual circuit has its own breaker downstream (e.g. 15 A or 20 A for normal receptacles). These circuit breakers are individually replaceable in the main breaker box.The historical tradition here was for GFCI devices to be installed externally in individual circuits (they replace a standard power socket and go in the same wall box). You install a GFCI as the first socket in a chain, and then daisy-chain the remaining normal sockets on the output terminals of the GFCI.However, regulations are tending towards having GFCI protection installed automatically at source. Hence you can get a combined GFCI and circuit breaker that installs in the breaker box protecting the whole circuit and removes the need for an external separate GFCI. For example, like this:http://www.homedepot.com/webapp/wcs/stores/servlet/ProductDisplay?productId=100187456

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 05:06:24 pm
content: Quote from: IanB on March 31, 2012, 05:03:48 pmYes, so let's make wild speculations and assumptions instead of working from what he's said. That's logical.QuoteSo like any installation.QuoteInsanity.QuoteRather more sane, congratulations to them on finally catching up with the rest of the world.E: Wait, 5mA? What happens if you sneeze at it or dare to connect a computer to the circuit?

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 05:25:36 pm
content: Quote from: Monkeh on March 31, 2012, 05:06:24 pmThat's easy. Computers are incompatible with wet areas

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2012, 05:29:55 pm
content: The illustrated item is designated for bathrooms - ie wet areas. So a likely thing is a hair-dryer or curling iron, where you want tripping at low current levels.The USA is hampered by having old installations that have to be great grandfathered in, you still find KT wiring around with open wire on wooden beams, and it still is in use. New stuff had to be done such that it would work more or less with what was there, so the kludges that have appeared. It would be good to make compliance mandatory, but that would cost a huge amount, and no politician will do so as it would be tantamount to stepping in a grinder with no reward.Here it went illegal years ago, the only grandfathered stuff is fuses with replaceable elements, and then to do any work the new stuff has to comply ( replace a 5A outlet with the same 5A outlet is ok, a new one with a switch where the old one never had one, or upgrading to 15A so you can use anything, needs to comply with current regs, so has to be to new standards with MCB, ELCB and insulation test for wire. Most electricians will only do so if they can do the rest of the installation to spec as well) as well as be cable in a conduit or with double insulated conductors. Sale of a building means compliance cert, so this does get upgrades done.

author: Monkeh
author_rank: Super Contributor
timestamp: March 31, 2012, 05:40:49 pm
content: And when you need protection for a circuit supplying a non-wet area?

author: SeanB
author_rank: Super Contributor
timestamp: March 31, 2012, 06:42:28 pm
content: 30mA is what is used here in South Africa. Funny enough you get industrial RCD units for water heaters that can have a limit of 100ma or 1A, but they are not approved for any other use.

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 07:51:02 pm
content: My GFCIs do not trip inappropriately with anything I have tried plugging into them. So I will worry about spurious trips if and when I encounter that problem.I don't feel any need for GFCI protection in normal home areas away from garden/garage/bathroom so I'm not going to go round and refit my whole house with GFCIs.

author: megajocke
author_rank: Regular Contributor
timestamp: March 31, 2012, 08:08:00 pm
content: Quote from: IanB on March 28, 2012, 08:45:01 pmAlso, it is important to be aware that the electrical installations in different countries may be very different.In (some or most) Norweigan electrical installations the normal 230V loads are connected between two different phases of a 3-phase 230V supply. If the supply is perfectly balanced you'll have 133V (that is, 230V/sqrt(3)) between phase and ground as well as between "neutral" (which is actually another phase) and ground. Measuring 126V would be perfectly normal!At least here in Sweden, having only ungrounded receptacles in some or most rooms is very common, and I suspect that this goes for other Schuko-using countries too. Grounded plugs fit in ungrounded receptacles, and the idea is that since there are no grounded items in the room you are safe as long as you don't touch two different defective appliances at the same time (which can be classified a double or even triple fault). This is no less safe than ungrounded non-doubly insulated equipment which relies on the same thing to get its second safety barrier. The plugs of this kind of equipment do not fit in grounded receptacles.In new installations grounded receptacles are required, to which non-doubly insulated ungrounded equipment can not be connected. New equipment is required to be either grounded or doubly insulated. Doubly insulated equipment has plugs that fit in both grounded and ungrounded receptacles.So, in the Schuko system you have the following kinds of receptacles:ungrounded receptacles in rooms where the room itself is insulating (not used in new installations)grounded receptacles: in rooms where ground is accessible, outdoors, kitchen etc. or recently everywherereceptacles into which only doubly-insulated equipment can be connected (pretty uncommon)Mixing ungrounded and grounded receptacles in the same room is not permitted in Sweden because this would introduce ground into the room, whose absence is relied on as the second safety barrier. (a Finnish poster earlier in the thread said the same thing applies for Finland) The receptacles into which only doubly insulated equipment can be connected can be mixed with the other kinds. They can be used in a room where ground is accesible, without requiring a ground wire to be available for the receptacle.As for equipment and plugs there are three different kinds too:grounded (fits in ungrounded and grounded receptacles): relies on the ground as a second safety barrierungrounded (fits only in ungrounded receptacles): relies on the insulated room as a second safety barrier.doubly-insulated (fits in all receptacles): the second safety barrier is internal to the equipment.Note that the way different plugs fit into different receptacles is opposite of that in the US, unless nongrounded US receptacles and plugs are understood to correspond to the doubly-insulated Schuko ones!

author: Unknown
author_rank: Unknown
timestamp: March 31, 2012, 08:47:50 pm
content: Quote from: megajocke on March 31, 2012, 08:08:00 pmThat's the reason why having someone knowledgeable on site is useful. Two phases from a three-phase supply would make sense, but makes it hard to draw any conclusions about the quality of the earth connection. The original problem was an apparent flow of current through kind.oslo's body, that current has to come from somewhere.Quote from: megajocke on March 31, 2012, 08:08:00 pmDoes this also require water pipes and radiators to be floating? Any requirements about carpet impedance? It's not too hard to get a shock while touching just a single phase, although I've never bothered to put an ammeter in series to measure the current.

author: IanB
author_rank: Super Contributor
timestamp: March 31, 2012, 09:02:40 pm
content: Quote from: alm on March 31, 2012, 08:47:50 pmI've never been able to get a shock from touching a single live wire while in a dry room. There were many times as a teenager that I handled live wires while sitting or kneeling on a carpeted or wooden floor and never felt a thing. Unfortunately as a youngster one has no perception of danger at all and it was entirely easy to be careless about whether equipment was unplugged before working on it.I imagine you would not be allowed to have any metal objects like water or gas pipes in a room where you are relying on room insulation to be a safety barrier.

author: megajocke
author_rank: Regular Contributor
timestamp: March 31, 2012, 09:18:38 pm
content: Well, theideawas that you wouldn't have any grounded objects.Water pipes (if any) and radiators are usually coated in thick paint, but nevertheless there usually are exposed metallic parts. It seems that these details were conveniently overlooked. Or maybe you were just supposed not to touch the radiators at the same time as electrical equipment. I actually saw a note attached to an old fuse box which said: "Do not touch radiators or faucets at the same time as electrical appliances.", or something to that matter.In new installations non-grounded receptacles are not permitted, so this is becoming a non-issue albeit slowly. If I understood correctly, GFCI protection is also a requirement. It is typically done with one central GFCI protecting all normal circuits. I'm not sure when the electrical code was changed, but buildings from the mid-90's usually have ungrounded receptacles in "dry" rooms.