Earth in EU/USA plug sockets

[Faringdon]

Hi,
We see lots of two pin plugs in the EU.
Do some EU wall sockets not actually have an earth connection?
In other words, any device connected to them would have to be in a plastic case, with no vent holes?
(ie double insulated)?

Ditto question for USA/Australia/China/Canada/Brazil and South America.

[themadhippy]

We see lots of two pin plugs in the EU.

look closer , them there schukos do have an earth

[IanB]

The sockets have an earth connection. The plugs are not required to make an earth connection if the connected device does not demand it.

[Swake]

Some older (like +40 years old) installations do not have an earth. Unfortunately not everyone has had the possibility to upgrade. Although public places should all have earth.

[tooki]

Hi,
We see lots of two pin plugs in the EU.

They’re common everywhere except the UK, basically. Many devices don’t need a ground. Even in the UK, you have devices with a plastic or disconnected earth pin.

Do some EU wall sockets not actually have an earth connection?

No. Excluding possibly some very old legacy installs that haven’t been updated in the better part of a century, earthed sockets are universal almost everywhere, as required by law.

You can look up the basic rules yourself, it’s not hard.

And as others have said, the Schuko plug (whose name literally is short for “protective earth contact” in German) has earth, it’s just a clip instead of a pin. The French plug also has no earth pin: the earth pin is in the receptacle, and the plug contains a female earth contact.

In other words, any device connected to them would have to be in a plastic case, with no vent holes?
(ie double insulated)?

That is not what double-insulated means. “Double-insulated” (Class II) means that the failure of one level of insulation cannot result in the user coming into direct contact with a mains conductor. This can be multiple layers of insulation, or reinforced insulation. It doesn’t mean all-plastic, and it doesn’t mean no slits. (Lots of AC-powered home AV gear is Class II, with the double square symbol, but is in a metal case with ventilation slits, using no earth.)

Ditto question for USA/Australia/China/Canada/Brazil and South America.

The standards vary by country; South America isn’t a monolithic electrical system. There’s a hodgepodge of voltages and plugs down there, sometimes even within a country.

The only country I am aware of that basically never uses earthed sockets is Japan. Everywhere else, earthed sockets are the norm (though in developing nations it’s not uncommon for the earth pin to not be properly connected!). But unearthed appliances are widely used.

So what is if you really want to know??

[Siwastaja]

Depends on exact country, but very generally:

1) Two-prong europlug: fits all sockets: obviously europlug socket, schuko (earthed) socket, and old-school unearthed 2-prong socket.
device must be double insulated and inherently safe against single failure regardless of potentials or faults in surrounding things.

2) Earthed plug: fits schuko (earthed) socket. Device does not need double insulation, because installation is made safe by having all metal cased things connected to the same potential through the earth connection, so no significant current can flow through the user if they touch two metal things at the same time, one of which is faulty. In theory, at least - assuming the earth connection is something that can't fail!

Then we have the case of old-school non-europlug two-prong non-earthed (round) plugs and sockets, well predating 1980-1990 or so. As double insulation was not required, they were made safe by the fact that such non-earthed sockets only exist in so called "dry" rooms with no plumbing, other sources of earth connections, not even earthed sockets. Basically this is a "floating" system. You would need two devices to develop simultaneous faults, one exposing line and another neutral into their cases, which is unlikely. Old legislation made it illegal to use extension cords to bring earthed supply into such rooms, for example.

These old single-insulated plugs and sockets have been phased out in all of Europe long time ago AFAIK, but you can still see them in old houses. There is no absolute urgency to upgrade because quite frankly, they never caused too many accidents. People modifying single-insulated equipment by cutting holes in the plug allowing it to plugged in rooms where it should not be operated was a real problem though, as the separation to different types of sockets as per room was a big convenience problem. Getting earthed sockets everywhere was the right choice, and later, GFCI/RCD made earthed installations truly much more safe.

(Before RCDs, earthed installations provided some false sense of security, as they completely relied on everything being correctly built with utmost care in the earth connection. If a product had dangerous earthing issues, then the surroundings of having everything else properly earthed made the thing more dangerous than what it would have been in the "floating" 2-prong "dry room" setting.)

[Lucien Nunes]

There's some interesting history behind why much of the world has the option of non-earthed plugs but the UK does not. As explained above, most systems that offer both earthed and non-earthed plugs for Class I and Class II equipment respectively, are designed so that both types fit the same earthed sockets.

In Europe, for class II equipment with low current requirements, the standard choice is the CEE7/16 Europlug, which is specifically the flat 2-pin plug rated at 2.5A with 4mm diameter pins angled slightly inwards. This is designed to fit all types of socket with 4.0-4.8mm contacts on 19mm centres, regardless of whether the socket has an earth. Thus the same plug suits countries with CEE7/1, 7/3 (Schuko), 7/5 (French etc.), Swiss, Danish, Italian, IEC 60906 (Brazil, SA) and obsolete types too. There are also higher-rated non-earthed variants such as CEEE7/17, which allow for 10A or 16A loads but only interface to a smaller selection of sockets. All of these, ultimately, are descended from and semi-compatible with an early non-earthed plug by Siemens, designed at a time when earthing was not widespread.

Then in the USA and systems derived from the NEMA standards, there is the 2-prong NEMA 1 type, which fits both legacy NEMA 1 outlets, and the standard 120V NEMA 5-15 and 5-20 grounded outlets. As with the European system, the basic non-grounded plug fits almost every outlet that has the correct voltage, and is descended from an original design by Hubbell that was created before grounding was commonplace. Less widespread but fundamentally similar is the Australian / NZ plug which can also exist in 2- and 3-pin compatible versions.

The UK's BS1363 plug is a special case for which there has never been, and cannot be, a non-earthed 2-pin variety. This is because the mechanism in many sockets, and as envisaged in the original specs, required the earth pin to open the safety shutters. If we don't need an earth pin for earthing, we must still have a plastic replacement for it, called an ISOD (Insulated Shutter Opening Device.) Part of the reason for BS 1363 being so different to many other plugs is that it was one of the most recent designs, from 1947, that was not compatible with any of its predecessors. But what about those predecessors?

This is where the old UK system starts to look very daft. Before 1947, we had three current ratings of plug (2A, 5A, 15A) with round pins, each available in earthed (3-pin) and non-earthed (2-pin) versions. But, although the line and neutral pin dimensions were the same for both versions, they were made to different standards and had different spacings between the pins. Therefore a 15A 2-pin plug did not fit a 15A 3-pin socket, and likewise for 2A and 5A. Thus there were six completely incompatible types in use plus a few specials like the Wylex.

So, in 1947 we had a re-think to get rid of this confusing array of different plugs, and came up with the fused, earthed plug that is BS1363. By this time, earthing was widespread, but the vast number of small Class II electronic goods that we use today didn't yet exist. So it probably seemed that there was little point designing a 2-pin non-earthed version of the plug that would complicate the shutter arrangements. As things have turned out, countries that had a non-earthed variant all along have ended up with a neater solution for small electronic goods today, while we have our later, 'better' plug that forces us to the larger earthed variant footprint even when not needed.

[mariush]

In Romania, in apartment buildings made before the revolution (1990) it was common practice to only have Earth wire at a socket near the bathroom (for washing machines or hair dryers) and one in the kitchen. It was all about saving money, cables going to ac sockets were  using copper, cables going to lightning were made of solid core aluminum.
 
Nowadays, I assume they would route earthing wire to every socket, as the wires are not that expensive.

[IanB]

So, in 1947 we had a re-think to get rid of this confusing array of different plugs, and came up with the fused, earthed plug that is BS1363. By this time, earthing was widespread, but the vast number of small Class II electronic goods that we use today didn't yet exist. So it probably seemed that there was little point designing a 2-pin non-earthed version of the plug that would complicate the shutter arrangements. As things have turned out, countries that had a non-earthed variant all along have ended up with a neater solution for small electronic goods today, while we have our later, 'better' plug that forces us to the larger earthed variant footprint even when not needed.

There was, however, a 2-pin non-earthed plug in widespread use into the 60's, which was basically the same geometry that became today's shaver plug. But back then, it was commonly attached to the two conductor cord of non-earthed appliances like lamps, toasters, radios and all sorts of things. The plug was simple, did not have plastic sleeves on the pins, and the socket was not shuttered. When BS1363 became common, the readily available shaver adapters allowed these two pin plugs to continue in use (it was often easier to use an adapter for the existing plug than to change the plug on the cord).

When I was growing up I used these two pin plugs as a convenient mains test fixture for powering things on the workbench as it was easy to attach a two conductor zip cord to them without needing a screwdriver. You just unscrewed the cap of the plug, put the conductors through the connecting lugs, and screwed the cap back on. It took just seconds.

[wasedadoc]

The (UK) house that my parents lived in for almost all of their married life was built sometime around 1951.  Originally all the socket outlets except the one for electric kettle in the kitchen were made by Dorman-Smith.  A 3 pin design with the earth pin diameter slightly larger than the other ones.  The unique aspect was that the plugs were fused but the fuse was not internal to the plug.  Instead the fuse was the live pin.  Imagine a slightly larger version of a current BS fuse as used inside today's 13 Amp rectangular pin plug but with the metal cap at one end having a protruding threaded portion about 6mm long. That end screwed into the threaded live contact inside the plug body. The fuse acted as the pin with the plain metal cap end going into the socket.  Different ratings of the fuses were available to screw in.

Pictures 6 to 10 at https://www.plugsocketmuseum.nl/DormanSmith1.html

[Haenk]

In other words, any device connected to them would have to be in a plastic case, with no vent holes?
(ie double insulated)?

Earth is not needed when double insulated, but it's not depending on the material of the case. Metal casing is totally fine, even with lots of venting holes. However there are test procedures poking with things into the case - the venting has to be small enough, to be not able to touch anything inside, like with a knife or a pen.
Plastic casing is only used due to being cheaper and being easier to mold into some stylish object (versus plain old metal box). Of course you have the benefit of screwing stuff directly into the case without needing to care about insulation.

[dmills]

The only country I am aware of that basically never uses earthed sockets is Japan.

The Philippines is I think another one that is frequently ungrounded in places that Western Europe would expect to be.

They actually have both grounded and ungrounded sockets, but just because something has a notional 'ground' contact, it should NOT be assumed to be connected (And if it is, it might just be wired to local neutral!).

Very different attitude to electrical safety over there.

[dmills]

Lots of hifi gear is double insulated in metal cases, basically because the double insulation is easier then reliably solving the earth loops in single ended IO connections any other way.

This does sometimes result in a tickle when you have a load of double insulated laptops or such hooked up as the leakage current tends to sum and can get high enough to be very obvious.

Apple lapdogs when plugged into a double insulated video projector and cheap class D powered speakers can be especially fun for this as they have a metal case connected to the negative side of the power supply, can sometimes get rather spicy. Cure is to earth any random bit of the setup.

[tooki]

The only country I am aware of that basically never uses earthed sockets is Japan.

The Philippines is I think another one that is frequently ungrounded in places that Western Europe would expect to be.

They actually have both grounded and ungrounded sockets, but just because something has a notional 'ground' contact, it should NOT be assumed to be connected (And if it is, it might just be wired to local neutral!).

Very different attitude to electrical safety over there.

I know that. I said that in the part of my comment that you cut off:

The only country I am aware of that basically never uses earthed sockets is Japan. Everywhere else, earthed sockets are the norm (though in developing nations it’s not uncommon for the earth pin to not be properly connected!).

The point about Japan is that they’re NOT grounded outlets with the ground not connected, but rather that 2-pin sockets are still the norm there. Grounded appliances come with a ground wire that you have to screw to it instead (so hilariously, there is a ground wire in the wall, and it leads to screw terminal on the outlet, rather than a pin receptacle!).

[langwadt]

plenty of plugs and sockets with no earth here, and most devices will be delivered with a schuko plug that fits but doesn't connect earth in a Danish socket

[newbrain]

Is any country apart from Sweden using specific plugs and sockets for ceiling mount light fixtures?

All apartments I've seen either have the old style ones or the EU-standard DCL ones.

I don't remember seeing those ceiling sockets anywhere else in EU or UK/US/CA/BR, definitely not in IT.

[themadhippy]

Is any country apart from Sweden using specific plugs and sockets for ceiling mount light fixtures?

Theirs a few about in the uk,hagers klick rose  https://www.tlc-direct.co.uk/Products/ASPCR2000.html  being the one ive seen the most  .There pretty rare in  domestic environments,more often found in commercial buildings.

[Haenk]

plenty of plugs and sockets with no earth here, and most devices will be delivered with a schuko plug that fits but doesn't connect earth in a Danish socket

About 3 years ago we were in an old feriehuset, which was great in having old 2-prong wiring and Schuko-adapters all over, even in bathroom and kitchen. The dryer in the bathroom required an earthed connection (as stated on the label) and had *very* noticable leak to the chassis. So much I considered it unsafe and forbid my wife to use/touch it when plugged in. Switched it on with that well known remote broom.

As for the swedish ceiling sockets - I have only seen those in Sweden, and I find them great.

[Siwastaja]

All apartments I've seen either have the old style ones

We use(d?) that exact type here, too. Before around 2000's, there was simply a terminal block in the ceiling and it was considered normal to wire it up yourself.

[langwadt]

Is any country apart from Sweden using specific plugs and sockets for ceiling mount light fixtures?

All apartments I've seen either have the old style ones or the EU-standard DCL ones.

I don't remember seeing those ceiling sockets anywhere else in EU or UK/US/CA/BR, definitely not in IT.

Denmark have these, https://sw5890.sfstatic.io/upload_dir/shop/category/Laurtiz-Knudsen---Lampemateriel---Lampestik.jpg

[langwadt]

plenty of plugs and sockets with no earth here, and most devices will be delivered with a schuko plug that fits but doesn't connect earth in a Danish socket

About 3 years ago we were in an old feriehuset, which was great in having old 2-prong wiring and Schuko-adapters all over, even in bathroom and kitchen. The dryer in the bathroom required an earthed connection (as stated on the label) and had *very* noticable leak to the chassis. So much I considered it unsafe and forbid my wife to use/touch it when plugged in. Switched it on with that well known remote broom.

Things like washing machines should be earthed, so they should at least have used a schuko to three-prong adapter

though, the leak was probably just the filter in the powersupply, unpleasant but not dangerous

 

[tooki]

Hi,
We see lots of two pin plugs in the EU.
Do some EU wall sockets not actually have an earth connection?
In other words, any device connected to them would have to be in a plastic case, with no vent holes?
(ie double insulated)?

Ditto question for USA/Australia/China/Canada/Brazil and South America.

You posted and then vanished.

I ask again (and this isn't a rhetorical question; I want an answer): So what is it you really want to know??

[Faringdon]

Thanks,
We want to produce a (400W peak) offline power supply for a product in EU. (+ elsewhere)
Thing is, power supplies for household items must be in totally enclosed plastic cases for safety reasons.........if you have that, then you need to have an internal metal foil  inside the plastic enclosure, otherwise you will not pass radiated EMC regulatory compliance testing.
...And if you have a metal foil surrounding the SMPS, then its best to connect it to earth...but if the two pin socket doesnt have an earth, then how can this be done?

Lots of AC-powered home AV gear is Class II, with the double square symbol, but is in a metal case with ventilation slits, using no earth

Thanks, may i ask what this metal case is connected to....or is it just "floating"?

[IanB]

but if the two pin socket doesnt have an earth, then how can this be done?

Where are you going to find a two pin socket with no earth in the EU?

[Benta]

Where are you going to find a two pin socket with no earth in the EU?

They're everywhere. Not every house was built within the last 10 years. You'll still find 1920s installations around.