Neutral connected to earth in wall socket. OK? Legal? - Page 1
Forum section: electronics / general

author: anfang
author_rank: Regular Contributor
timestamp: October 09, 2016, 06:29:03 pm
content: A light was flickering and I said to myself: it is time to change that old wall socket. I unmounted the Schuko socket and found... the neutral cable connected to the earth prongs and no earth connection! How is that OK? Isn't it extremely dangerous? And the connection has been done on purpose. Why?On top of that, the cables are all black, both the live and the neutral cable.The landlord will have a thing or two to explain...I took this photo. In blue the piece of wire connecting the neutral to the earth prongs.

author: bktemp
author_rank: Super Contributor
timestamp: October 09, 2016, 06:47:13 pm
content: I don't know for Austria, but in Germany you see this quite often in older houses with the electric installation done about 40 years ago. For new installations it is not allowed anymore because a RCD ("FI") is mandatory since 2009. But there is no need to change existing installations.It is not really dangerous, but there is no ground fault protection.

author: Kilrah
author_rank: Unknown
timestamp: October 09, 2016, 06:53:25 pm
content: In Switzerland it's the same, old installations had earth and neutral connected and old buildings do not need to be upgraded until the next major overhaul.

author: Zero999
author_rank: Super Contributor
timestamp: October 09, 2016, 06:56:36 pm
content: Neutral and earth are the same thing. The neutral will be connected to the earth, where it enters the building, and is earthed at multiple points. It's known as a TN-C network.Quotehttps://en.wikipedia.org/wiki/Earthing_system#TN_networks

author: wraper
author_rank: Unknown
timestamp: October 09, 2016, 06:58:58 pm
content: Not safe and not legal. Earth and neutral can be connected together but not at the socket as it is outright dangerous may any wiring fault occur. If neutral wire gets disconnected anywhere, the enclosure of the device will be at live voltage.

author: wraper
author_rank: Unknown
timestamp: October 09, 2016, 07:00:18 pm
content: Quote from: Hero999 on October 09, 2016, 06:56:36 pmNot in this case, though. because of:Quote

author: jahonen
author_rank: Super Contributor
timestamp: October 09, 2016, 07:18:56 pm
content: This was the common way here in Finland until relatively recently (I think sometime during 90's this changed to present way). But from fault protection perspective (which is the purpose of the appliance PE connection), that connection works ok'ish. It blows fuse in case the device housing develops a short to L conductor. Note that even although the PE might seem to come somewhere else (green-yellow wire exists), it might actually come from nearby junction box, so presence of the green-yellow wire does not guarantee that PE is wired into actual distribution panel.Nowadays, the system used here in Finland is TN-C-S so that neutral (PEN) is splitted into PE and N on main distribution panel (this point is also connected to grounding electrode around the building foundation), and PE and N will never be merged afterwards. All PE conductors are guaranteed not to be derived from N wire in any other place than from the main distribution panel PE-N connection.Regards,Janne

author: janoc
author_rank: Super Contributor
timestamp: October 09, 2016, 07:31:20 pm
content: Quote from: wraper on October 09, 2016, 06:58:58 pmWhich happens especially in old buildings that actually lack the third - earth - wire. Which was very common in older installations in Slovakia - the earth pin was wired to the right (neutral) contact too and there were only 2 wires going to the outlet. So this is really a bad idea.

author: 128er
author_rank: Regular Contributor
timestamp: October 09, 2016, 07:35:48 pm
content: It is neither pretty nor safe. But better as none PE connection at all. The common term for this in german is "klassische Nullung" . And as wraper said, if your neutral becomes bad, the device can be at live voltage.

author: rstofer
author_rank: Super Contributor
timestamp: October 09, 2016, 08:09:08 pm
content: If you consider a ground fault of high magnitude occurring on ANY circuit connected to the transformer (even in your neighbor's house) and you toss in the fact that the fault current MUST get back to the neutral point of the transformer (to complete the circuit), every grounded neutral in the system is going to be carrying some portion of that fault current.The fault current goes to ground then gets into the neutrals (because they are connected to grounding conductors) and then flows on to the transformer neutral point.In the US, fault current for residential locations is usually less than 10,000 amps and likely less than 5,000 amps but, still, the damage than can be done by fault current flowing in small neutral conductors can be substantial.Ordinarily, the neutral is grounded at the transformer and again at the service entrance point and nowhere beyond that point.

author: chris_leyson
author_rank: Super Contributor
timestamp: October 09, 2016, 10:02:14 pm
content: It's illegal and doesn't meet wiring standards unless you live in a so called third world country where nobody give a shit. What if your house or flat burnt down or you were killed because of a neutral fault putting AC onto the neutral, in your case earth, your insurance company wouldnt pay out a penny.

author: Cubdriver
author_rank: Unknown
timestamp: October 09, 2016, 10:06:27 pm
content: Here in the US it's sometimes called a bootleg ground, and is against code. I'd expect it likely is where you are, too. It's definitely dangerous if you think about it - if the neutral somehow opens up between the connections at the receptacle and the panel, then the neutral pin on the plug will be pulled high by whatever is plugged in to it. This will also pull the ground pin high as they're tied together, and if the device has a 'grounded' metal enclosure, it's now at near line potential. Yike!!-Pat

author: Brumby
author_rank: Unknown
timestamp: October 10, 2016, 12:38:34 am
content: Quote from: Hero999 on October 09, 2016, 06:56:36 pmIn terms of voltage reference - then, yes. But in terms of current flow, especially in fault conditions, then it's not so clear.From what other posters have stated, this arrangement is not uncommon in older installations in some areas - but as has also been stated, it's not a great idea. It's notinherentlydangerous - just far less than ideal in a fault condition.As far as RCD protection is concerned - if a person bridges the active of an appliance and the casing of that appliance, then there will be no protection.However - if the neutral is earthed at some point (preferably at the entry to the building) then there will be RCD protection if someone were to bridge the active of the appliance to another earth-connected conductor, such as a metal water pipe.

author: EEVblog
author_rank: Unknown
timestamp: October 10, 2016, 12:47:27 am
content: Not legal in Australia.

author: rob77
author_rank: Super Contributor
timestamp: October 10, 2016, 01:19:56 am
content: Quote from: wraper on October 09, 2016, 06:58:58 pmit's called 2 wire and it's legal...but it's not legal for NEW installations (unless the cross-section of the PEN wire is at least 16mm2). btw... it was a pretty common setup in the past, but nowadays 3 wire installation is mandatory with separated N end PE.one of the reasons why separated N and PE is required is the fact that you have to have a RCD protection on all all outlets in a household. i think the whole EU is more-or-less aligned so it will be very similar everywhere else.

author: Red Squirrel
author_rank: Super Contributor
timestamp: October 10, 2016, 01:24:40 am
content: Not right to do that, but technically it should be ok. Not the way I would do it though...Basically the neutral is tied to ground at the panel, but after that it's NOT suppose to be connected and suppose to be treated as two separate things.My guess is this is an old install and there is no ground wire at all, so they did this to compensate. The better way of doing it is to install a GFCI outlet there. While it won't be grounded, it will trip if there is a fault. Ex: a light fixture chassis gets energized for some reason, normally it would go to ground and trip the breaker, but since there is no ground it won't do anything and be a danger to anyone that touches it. With a GFCI if you touch it and some of the power goes through you and to ground, then it will trip the GFCI.A fun experiment though is you can put a paper clip in the neutral side of a plug and not get shocked. Great way to freak out friends! Just make sure it's wired correctly before you try that trick unless you want a perm.

author: AlfBaz
author_rank: Super Contributor
timestamp: October 10, 2016, 03:20:51 am
content: Ignoring RCD's, GFCI's etc for the moment, as many domestic installations still don't have them, then...Earth should only ever carry current in a fault condition. Neutral, on the other hand, is a current carrying conductor. It has flowing through it the complete load current.If there is any voltage drop (and basic oms law will show that there always be some, more if there are bad connections or undersized wiring) and you connect earth to it at the outlet, you are essentially raising the potential of any grounded chassis with respect to any other grounded item nearby that is not powered or is earthed "incidentally", such as a steel sink via metal plumbing. This "small" potential difference has very small source impedance and under the right conditions can cause sufficient current flow to cause death or fire

author: Brumby
author_rank: Unknown
timestamp: October 10, 2016, 06:09:10 am
content: Quote from: Red Squirrel on October 10, 2016, 01:24:40 amWhile most of us here will understand what you would be doing here - I would strongly advise NOT. If you have someone who doesn't know what's going on see you do it - or heard about it second hand - and tried it themselves, then there is a high risk of something bad happening. Add to this the fact that there is no good reason for doing this other than 'freak out' value and it's not something I'd encourage in any way.I actually go the opposite way and keep any such activities to myself - and even in those, I keep a healthy respect for the old saying "One flash and you're ash."

author: SteveyG
author_rank: Unknown
timestamp: October 10, 2016, 09:24:03 am
content: Quote from: chris_leyson on October 09, 2016, 10:02:14 pmIt's against wiring regulations, but certainly not illegal. No crime is being committed!

author: focovario
author_rank: Contributor
timestamp: October 10, 2016, 10:19:40 am
content: Quote from: chris_leyson on October 09, 2016, 10:02:14 pm

author: focovario
author_rank: Contributor
timestamp: October 10, 2016, 10:22:55 am
content: Apology for misquoting chris–leyton.This is what he wrote:It's illegal and doesn't meet wiring standards unless you live in a so called third world country where nobody give a shit".This is my opinion:I am sure chris_leyson can convey his technical wisdom without offending people from other nations on an open forum. To express such a strong opinion I gather he has extensively traveled the world. If that is the case, he certainly has been meeting the wrong people.

author: DenzilPenberthy
author_rank: Frequent Contributor
timestamp: October 10, 2016, 10:46:54 am
content: Quote from: SteveyG on October 10, 2016, 09:24:03 amIn the UK it's prohibited in installations covered by BS7671 aka 'the wiring regs' but as you point out, this is not 'illegal'.It is however also prohibited by the Electricity Safety, Quality and Continuity Regulations 2002. Part II, paragraph 8, (4) "A consumer shall not combine the neutral and protective functions in a single conductorin his consumer’s installation." I believe this does make it illegal.I'm very happy to be corrected by any passing lawyers or people who've read the ESQCR in more depth than I have...

author: TassiloH
author_rank: Regular Contributor
timestamp: October 10, 2016, 11:45:10 am
content: This was common in Germany and adjacent countries between the 1950ies and 1970ies. As someone else said, "klassische Nullung". It would be quasi-illegal in new installations or when an existing installation is overhauled or largely modified, but otherwise the standard when the electrical system was originally installed still applies (in Germany, "Bestandsschutz"), so there is no legal need to upgrade it to current code regulations.The problems with this kind of installation are:* No RCD (unless you install an RCD-Outlet combo for each outlet)* grounded equipment is on live potential if wiring between outlet and distribution box fails* PE and N share a wire, so if a high current device is connected, the PE potential of the outlet will shift a few volts compared to real ground (voltage drop over the wire) and also compared to other, less loaded outlets. If you have grounded audio or computer equipment connected to the outlets and you run a data or audio cable between them, a rather large current could run via the ground of the data cable dut to the different PE potentials.

author: tszaboo
author_rank: Super Contributor
timestamp: October 10, 2016, 11:51:59 am
content: Quote from: 128er on October 09, 2016, 07:35:48 pmThis. The house does not have earth wire.It is even possible that the house was built before electricity. You know, Europe is old. Sometimes I wish, we would just demolish all buildings every 30 years, like the US. But then again, I take a walk, and citys are breathtaking and beautiful, instead of brutalist concrete jungle.

author: Jeroen3
author_rank: Super Contributor
timestamp: October 10, 2016, 12:11:56 pm
content: If the pole in your street falls over and the engineer connects L/N the wrong way your PE is live.I'd recommend to:- Properly wire earth.Or, lazy approach:- Remove earth fault, and replace socket for Type C.

author: RGB255_0_0
author_rank: Frequent Contributor
timestamp: October 10, 2016, 12:33:16 pm
content: Quote from: Jeroen3 on October 10, 2016, 12:11:56 pmWouldn't that happen anyway with TN-x system regardless?

author: rob77
author_rank: Super Contributor
timestamp: October 10, 2016, 12:50:12 pm
content: Quote from: Jeroen3 on October 10, 2016, 12:11:56 pmsorry that's bullshit... how the hell could a technician swap one of the phases with the PEN wire at the pole ? and even if he somehow miraculously did... how could the PEN wire become live ? the PEN wire is grounded with a ground plate dug into earth at the input to the house/building. so swapping a phase wire with PEN at the utility pole would cause HUGE fault current flowing to ground and bring the whole thing down.the input to house or building is ALWAYS a common wire for both neutral and ground marked PEN, then the PEN wire is split up to separate PE and N wire in the distribution box... and from there it's 3wire wiring with L + N + PE wires and it's forbidden to connect N and PE again after this point of separation in the distribution box.in the past a 2 wire system was used - where you had only 2 wires to outlets: phase and PEN and the PEN wire was connected to both neutral and ground of the outlet.the 2 wire is system is not dangerous and is completely legal - no-one needs to replace the wiring in the older houses. however for every new installation or rebuild the 3 wire is mandatory and RCD/GFCI is mandatory for every outlet used by ordinary persons (RCD/GFCI don't work with 2wire installation).

author: helius
author_rank: Super Contributor
timestamp: October 10, 2016, 12:50:15 pm
content: Quote from: NANDBlog on October 10, 2016, 11:51:59 amI'm not sure where these perceptions come from? The median age of buildings in the US is over 40 years, so there are equal numbers built since 1975 as those standing from before 1975. In Boston and New York, 19th century buildings (before electricity) are common, up to 20% according to census data.If anything, I would expect the structures in older US cities to have greater median age because they were never carpet bombed.

author: station240
author_rank: Unknown
timestamp: October 10, 2016, 12:56:55 pm
content: The risk is that should the bond between the earth and neutral break at the switchboard end (wire disconnects, earth stake loose). Then the metal case of every appliance can float high.

author: Zero999
author_rank: Super Contributor
timestamp: October 10, 2016, 01:01:56 pm
content: Quote from: wraper on October 09, 2016, 07:00:18 pmYes it is a TN-C network. The neutral and protective earth share a conductor, right up to the wall socket, where they split and become separate conductors in the mains plug and device's cable.QuoteI think what you're referring to is a TN-C-S network, where the neutral & earth are only shared between the distribution transformer and the property's distribution board.Quotehttps://en.wikipedia.org/wiki/Earthing_system#TN_networksQuote from: wraper on October 09, 2016, 06:58:58 pmThe same can happen with a TN-C-S network (separate protective earth and neutral conductors in the building's wiring), if there's already a high leakage current between phase and earth and a break occurs in the protective earth conductor. Fortunately on modern installations the RCD will trip due to the high leakage current so the second fault isn't dangerous, as the power will already be interrupted.As far as legality is concerned: as many other people have pointed out, a TN-C network (shared neutral and protective earth inside the building wiring) legal for old wiring in some jurisdictions but new wiring has to have a separate PE conductor.

author: Jeroen3
author_rank: Super Contributor
timestamp: October 10, 2016, 01:07:19 pm
content: Quote from: rob77 on October 10, 2016, 12:50:12 pmThey do make this mistake sometimes. It causes major damage with three phase systems. They even manage to perform this trick on entire streets every few years.And if I swap L/N in my junction box I have no issue. N is not connected to PE at my house. It is at the transformer building.Not sure, but Austria uses similar setup iirc. Only with poles due to terrain difficulties.

author: tszaboo
author_rank: Super Contributor
timestamp: October 10, 2016, 01:28:05 pm
content: Quote from: helius on October 10, 2016, 12:50:15 pm15% of germany (was carpet bombed) is over 100 years old, and another 60% is built before 1970. You can bring up New york, as an example, but it is going to be the exception.http://eyeonhousing.org/2012/08/the-geography-of-the-age-of-the-housing-stock/I'm not going to do a search for the date, from which earthing is necessary. I believe it to be in the 70-80s.

author: rob77
author_rank: Super Contributor
timestamp: October 10, 2016, 01:30:21 pm
content: Quote from: Jeroen3 on October 10, 2016, 01:07:19 pmdo you have 5 wire distribution network then ? in Europe usually the network is 4 wires: 3 x L + PEN , the PEN is the separated into PE + N in the house/building and in addition the PE is grounded with a ground plate dug into ground.

author: Zero999
author_rank: Super Contributor
timestamp: October 10, 2016, 02:53:42 pm
content: Quote from: Jeroen3 on October 10, 2016, 12:11:56 pmThat would be impossible in locations where all cables after the distribution transformer are buried underground, which is often the case in urban locations. Quite often buried cables consist of a tube which is earth/neutral with no insulation and the phase conductors in the middle.Quote from: rob77 on October 10, 2016, 12:50:12 pmThat's a bit of a generalisation. There are other possibilities, such as having a separate neutral and earth from the transformer to the property (TN-S) or no earth between the property and distribution transformer and connecting the earth conductor to a buried electrode (TT).https://en.wikipedia.org/wiki/Earthing_system

author: Jeroen3
author_rank: Super Contributor
timestamp: October 10, 2016, 05:53:53 pm
content: Quote from: rob77 on October 10, 2016, 01:30:21 pmPhase and Neutral 40 Amps. With earth rod. But only wired to bathroom, kitchen, central gas heating and garage.

author: Kevin.D
author_rank: Frequent Contributor
timestamp: October 10, 2016, 06:18:00 pm
content: Quote from: rob77 on October 10, 2016, 12:50:12 pmI think it must be different where you are then since here In a TN-C-S system it is not required to have separate plate or rod buried to earth at property since the earth is being provided by the feeder Neutral (which is earthed at multiple points by the supplier but not necessarily at each property). My house used to be TT (Tera-Tera) system which must provide it's own earthing point using a buried rod/plate at each property. It's was converted to TN-C-S some years ago at last rewire, one of the benefits of this system is that individual properties no longer need to maintain/have there own earth rods/plates.So this means a mix up of phase(L)/pen(N) to an individual property could happen at the suppliers entry box. I actually bought this up a few months a ago with someone who was then discussing the various reasons why anyone should never use/trust a neon screwdriver as an indicator of safety but always use and trust his meter instead. I agreed and then I thought of this scenario (L-PEN swapped at property service head) as one scenario that would actually result in your meter giving a false safe reading but a neon still would indicate live.It's unlikely yet still possible :- if this happens on a property that was fed by plastic water/gas pipes (so therefore no other earthed point's in the property) and main breaker (double pole) is off then all neutral/earthed metal work inside property would now be live via the PE connection to N service head (which bypasses main breaker). But since there is now no neutral/earths present (o/c with main breaker off) within property wiring then measuring anywhere after main breaker between L-N,L-E, E-N would show nothing on a Voltmeter. A neon though which only need capacitive coupling to earth would still indicate N,E are live.Regards.

author: janoc
author_rank: Super Contributor
timestamp: October 10, 2016, 08:07:30 pm
content: Quote from: chris_leyson on October 09, 2016, 10:02:14 pmMate, I dare you to get out of your living room and actually check some old installations around you in the UK. You will be likely *very surprised* what you will find.Then, once you have all that fixed, you can call other places "third world countries"

author: Ian.M
author_rank: Super Contributor
timestamp: October 10, 2016, 08:33:51 pm
content: Its *extremely* rare to see anything like that in the UK. Since the introduction of the BS1363 plug/socket system in 1947, an Earth connection to each BS1363 socket has been mandatory and the pre-BS1363 sockets were round pin, so visually distinct, and usually had to be replaced to make a property saleable. Its often a condition of buildings insurance that an electrical inspection has been performed within a certain number of years and any issues found remediated and DIY work now requires inspection so you typically only see the like when a resident since WWII or shortly thereafter who hasn't had significant electrical work done since the '60s dies or is taken into care.

author: G7PSK
author_rank: Super Contributor
timestamp: October 10, 2016, 08:40:26 pm
content: The earth and neutral are very often one wire up until they reach the meter cabinet especially in rural areas, two wires to the house with the neutral earthed at the transformer and the house.

author: janoc
author_rank: Super Contributor
timestamp: October 10, 2016, 10:59:41 pm
content: Quote from: Ian.M on October 10, 2016, 08:33:51 pmWell, consider yourself lucky then - most of the continent doesn't allow such installations anymore, but unless the building is being renovated/major work is being done, there is usually no obligation to replace the wiring (= enormous expense)E.g. in Denmark where I lived or here in France it is very common - in my current apartment which is in a fairly recent block of flats (perhaps 15-20 years old max.) I have several outlets that have only two pins (no ground) and are not even recessed - similar to the US-style outlets, only with round holes, so if you aren't careful, you could get shocked while inserting/removing the plug. In Denmark you will commonly find round outlets (like the French or German Schuko style) but with no earthing prong nor contact - only two pins for live and neutral.Two wire/no ground wiring is still fairly safe for normal indoor installations (unless some retard connected the neutral and grounding pins in the outlet!) where most of the appliances are doubly insulated anyway. The only exceptions are typically large appliances like water heaters, ovens, washing machines, etc. - there it was common to require separate grounding for them.

author: SteveyG
author_rank: Unknown
timestamp: October 11, 2016, 07:12:55 am
content: Quote from: G7PSK on October 10, 2016, 08:40:26 pmNormally the opposite. TT is usually used in rural areas, TN-C-S is not allowed for farms etc. I guess it depends how 'rural' you mean.All the properties near me are TN-S.

author: richard.cs
author_rank: Super Contributor
timestamp: October 11, 2016, 11:50:52 am
content: Quote from: helius on October 10, 2016, 12:50:15 pmIn the UK we don't really consider 19th century building "old". I live in Southampton which was fairly heavily bombed but living in a 19th century house here is not at all unusual, and once you get a few miles outside the city nor is drinking in a 16th or 17th century pub.

author: anfang
author_rank: Regular Contributor
timestamp: October 11, 2016, 02:59:17 pm
content: Thank you all for the great discussion, I was just ranting against my landlord...Anyway, my landlord says that because the flat has not undergone any major change, he doesn't have to install an earth wire, the question has already been discussed with the previous tenant.What is the safest option now?Remove the earth-neutral cabling from the wall sockets?Leave the earth-neutral connection but check that the neutral pole is always connected to the neutral cable?The sockets are all Schuko sockets, where the earth prongs are always exposed and that the whole installation is very shabby: there are rooms where only red cables have been used, other are black-only, another one had only neutral cables (true story... and I wondered why I could not get any fixture to work...).

author: 128er
author_rank: Regular Contributor
timestamp: October 11, 2016, 04:31:41 pm
content: If I was in your situation, I would leave the PE-N jumper as they are and check all the connections at the sockets and in the circuit breaker box. And perhaps in the terminal boxes (right term? "Abzweigdosen") which you have access to. And on top of that (If you have access to one) you could also check all your sockets with an installation tester like the Gossen Metrawatt Profitest. You could check for example the mains impedance, ZL-N.

author: electr_peter
author_rank: Unknown
timestamp: October 11, 2016, 08:03:10 pm
content: Safest option would be to remove N-E link and install RCD socket or RCD plug/socket adapter. Just in case something goes wrong. RCD only needs L and N to work, E is not needed.In Lithuania N-E connection in the socket is very common practise because old and semi old buildings had only L/N wiring installed. Such practise is called "Inulinimas" in Lithuanian (literally means "zeroing" or "connecting to zero") in contrast to "Izeminimas" (proper grounding, "connecting to earth").N-E connection in the socket is not the end of the world, but it is not a good thing. It leaves potential for L-N swap (which puts live on "earthed" metal parts) and leakage currents. However, because of lack of grounded appliances in near vicinity, earth impedance to a person might be slightly higher than in properly earthed installations (higher impedance - less potential current though a person). Depends on situation, of course.

author: janoc
author_rank: Super Contributor
timestamp: October 11, 2016, 08:08:43 pm
content: Quote from: richard.cs on October 11, 2016, 11:50:52 amYou mean like the anecdote of my ex-colleague? He went to a conference in Oxford and was told that the event is in the "new building". After good 30 minutes of fruitless search of anything resembling modern he was shown a 600 years old building with a sign on the wall saying "New College". When he sarcastically observed what "old building" would then mean, he got pointed over to an 800 years old one ...New can be pretty relative term, indeed. I am living in a town that has buildings standing (and still in use) remembering the times of Joan of Arc (she has been captured just outside of the city walls here).

author: SteveyG
author_rank: Unknown
timestamp: October 11, 2016, 08:47:37 pm
content: Quote from: electr_peter on October 11, 2016, 08:03:10 pmI disagree. Keep the connection in place but replace socket with an RCD model. At least then there are other methods for the RCD to correctly trip rather than just electric shock, e.g. if an internal line conductor were to contact the metal case.

author: electr_peter
author_rank: Unknown
timestamp: October 11, 2016, 09:14:15 pm
content: Quote from: SteveyG on October 11, 2016, 08:47:37 pmYour suggestion is to keep N-E connected and add RCD after N-E connection. Good point, this would allow RCD to trip in more cases. Mains in (L+N) -> N-E connection -> RCD -> socket -> device. It could fit in a single socket.Without N-E connected RCD would trip only when A) person touches live part or B) there is massive leakage current from live to outer metal case to earth. Case when metal is energised but too small leakage current flows would not be covered by RCD with N-E disconnected.