In my travels around, I’ve seen many a variety of plugs and sockets and have often mused on which ones are the best on the grounds of safety, neatness and convenience. I’ll stick with the world of 230V phase to ground here as the parallel blade/round ground North American standard seems to be widely used in the 115V world – please correct me if I am wrong. I have personally experienced (held, inserted and often dismantled/wired) the following and have noted their quirks and foibles. UK fused 13A square pin, UK 15A, 5A, 2A round pins, Euro plugs both French and rest-of-Europe types, Australian/New Zealand incline blade 10A, Argentinean modification of the aforementioned and a Chilean in-line three pin. In addition to these are various two round pin plugs of many diameters and spacings as well as the extensive varieties of NEMA types used in North America.
A lot of these have many things in common but there are major differences and contradictions. In general a global standard that I dare suggest at the end would incorporate all of the following features which are not all possessed in any of the systems above.
First of all it has to be as safe as reasonably possible with built in features to prevent accidental contact with the energized connectors or sockets, i.e. some form of shuttering on the socket and shielding on the pins of the plug. A good example of this is the UK 13A square (OK it’s oblong!) pin plug system with ground pin releasing the shutters on the phase and neutral and plastic sheathing on the energized pins adjacent to the plug body.
The plug must fit snugly and positively into the socket without all that limp flapping around that one can get with NEMA style parallel blade type, especially the ungrounded ones.
Likewise it should be robust. This pins or blades should not readily bend or break like the NEMA ones often do. The Ozi/NZ blades don’t readily bend.
It must be compact. Both the UK (new and old) and the Euro Plugs are bulky. The UK 13A is sized to contain an internal fuse but that is only to provide protection to the appliance cord on a 30A fused ring main. I used, as a Brit, to think this type of system was state-of-the-art until PaulUK showed me the error of my ways. The ring main should be dispensed of and this new unfused plug and socket system would not be allowed on it – radial branch circuits only like the rest of the world.
The system must incorporate a non-bypassable grounding (earthing) system but would not require a ground pin on ungrounded equipment. This has impact on its compactness and further rules out the UK system of using a ground pin (even a plastic one!) to move shutters and ensure polarization. It likewise rules out the French Euro plugs which rely on a grounding pin, contained in the socket, to force polarity. I’ll enter the orientation debate here and state that the system should have the grounding (earthing) conductor at the top. In my mind the weight of argument (which occasionally rages freely on the General Section) favours this orientation. IMHO the common North American and Antipodean sockets are upside down!
The system must be polarized! This rules out the non-French Euro plug and any system that uses symmetrical phase and neutral pins on ungrounded plugs. The North Americans very early got round to making one blade wider than the other to ensure polarity where required on ungrounded plugs and is almost a standard on 115V systems. Of course, their 230V 15A plugs don’t need to be polarized as that comprises an Edison circuit with twin phases. In my mind, the cleverest system is the Australian/New Zealand standard that uses non parallel blades. Polarity must be global and a situation like Argentina which uses Ozi/NZ plugs with reverse polarity must be avoided at all cost.
It should be standard that the phase connector in a socket is switched so that the plug does not have to be removed or inserted under load.
The system must use plugs whose pins are at a right-angles to the cord. This applies likewise to any socket face on an extension cord. Plugs with pins parallel to the cord cause the cable to stick out of the socket which takes up more room on a work surface - they are liable to get snagged, tugged and look just pain ugly. The orientation of the socket and plug should be such that the cord goes straight down the wall – UK influence speaking here! This will have implications for duplex sockets – this useful configuration will require them to be mounted besides each other rather that above each other as in North America so that the cords do not interfere with the other socket. Another reason for having right-angle plugs is that they cannot easily be pulled out of the socket by the cord (either by accident or design) and a right-angled socket on an extension cord makes it less likely to part company with its plug when the lot is dragged along the ground – the resultant extended cable ends up more or less straight.
Finally the plugs must be rated sufficient for my 3kW hot water kettle and those 10A ones found in Oz/NZ are just not rated high enough!
So what does my proposed international system look like? It is based strongly on the self-polarizing Australia/New Zealand standard (non-parallel blades) but with the grounding (earthing) blade up, and with switched duplex sockets mounted side by side. The plugs would be rated to at least 13A and have the out-sides of the energized blades partially sheathed to prevent accidental contact on insertion or removal. A shuttering system would make it difficult for anyone to insert a foreign object into the socket and yet would not require a grounding blade to open them – equal pressure system maybe. Only right angle plugs with the cord emerging opposite the grounding pin side would be allowed on both two and three pin varieties. Unless the fuse was very small, they would not be fused and therefore not fitted on ring-main systems.
Pulls on steel helmet …
Oh, and just before I retire to my fox-hole, this new standard may eventually be used in new North American domestic installations which use 230V phase to ground (putting grunt into the average American home) and introducing the bayonet cap light bulb for the high voltage lighting. A new world standard! We’ll work on that frequency issue next.
Or like the Euro/UK recepticals, have the face recessed so than nothing can come between the plug and the receptical face.
On the American 230V thing, as a good deal of appliances (including the bi-pin bayonet lamp) are double insulated and apparently polarity agnostic, I don't see really any need to change to an earthed end 230V supply.
AS for the frequency, I don't see a lot of appliances really caring, as they are either resistive, Universal motor, or SMPS, and could otherwise be designed to work on either frequency, and either an end or center ground supply.
Re: A world standard plug system???#135042 12/20/0212:52 AM12/20/0212:52 AM
Hutch, Your comments make very interesting reading. However,how do you connect your 3Kw kettle at the moment?. If we had a 3kW kettle over here,we would connect it via a 15Ampere socket and plug. Our jugs are only 2000Watts.
Re: A world standard plug system???#135043 12/20/0212:54 AM12/20/0212:54 AM
I nominate the Swiss plug. It's a compact grounded three round pin plug (only slightly wider than a Europlug), fits in a recessed outlet and the ground pin on the plug is offsett by a few millimeters.
The Swiss grounded sockets also accept two-pin Europlugs.
The Chilean 3-in-line plug that you cite is the standard Italian plug. It comes in 10- and 16-amp versions (distinguishable by the pin diameter and spacing).
My problem with small plugs is that people with arthritic hands will not find it easy to pull such plugs out of a socket. There's one British company that I know of that makes plugs with a pull-ring on the cover (sort of like the handle on a tea-cup).
Also having the flex enter the plug straight on is sometimes good in case of a severe emergency (such as accidental electrocution, mangling, etc.) where you can yank that plug out from across the room (without damaging the more expensive wall socket).
Of course this is potentially damaging to the plug (prongs can break and the cable will develop internal breaks).
[This message has been edited by SvenNYC (edited 12-20-2002).]
Re: A world standard plug system???#135044 12/20/0206:44 AM12/20/0206:44 AM
2.) Firm fit in socket. Recessed sockets offer this.
3.) Pins should not bend. This means thick blades/pins, like the UK, South African or Schuko.
4.) Compact. A double sockets should fit in one box.
5.) Non bypassable earth. This means placing the earth pin in line or nearly in line with the other pins to make it hard to saw off.
6.) Earthing up or down doesn't matter if you cannot touch the hot pins/blades.
7.) Polarized: Not for the equipment (try to polarize the US 240V ), but for safety with present UK plugs. (Small .5 mm2 wires used. Thus you need the fuse.) Then only the grounded plugs need to be polarized.
8.) 3 kW kettle: 3000/230V = 13A. As 15/16A plugs are standard in many countries, 16A would seem to be the right choice.
Now you are in for a shock: Such a plug exist! It has been the world standard since 1986! Yet, no country has adopted it.
There is also a official 115V standard plug since 1997: The US 15A plug.
I have bought the standard for the 230V plug (IEC 60906-1) (something like $70, 36 pages long) and have reproduced some drawings below. (Without permission, so I have to remove them if IEC complains.)
Ignore the protective surface: It's only an option to a recessed socket.
[This message has been edited by C-H (edited 12-20-2002).]
Re: A world standard plug system???#135045 12/20/0209:55 AM12/20/0209:55 AM
Sven: The Swiss plug is almost identical to the IEC 60906: The Swiss has the earth pin offset 5 mm instead of 3 mm and the pins are only 4 mm dia. instead of 4.5 mm. More importantly, it lacks insulating sleeves.
I have one, and agree with you that it is in a suitable size. You cannot make a plug much smaller than this, since it would be difficult to attach a cord.
[This message has been edited by C-H (edited 12-20-2002).]
Re: A world standard plug system???#135047 12/20/0210:38 AM12/20/0210:38 AM
Sven: I pull plugs from the wall by the cord all the time: it doesn't seem to harm them.
Classicsat: You are right, UL won't allow appliance to consider polarity. They insist on it being maintained, but never use it. As the voltage tolerances of the US 240V (220-254V) fall within the international 230V tolerances (207-253V) all 230V appliances should run in North America too. (If it accepts 60Hz, but everything but clocks and motors should do so.)
[This message has been edited by C-H (edited 12-20-2002).]
Re: A world standard plug system???#135048 12/20/0211:43 AM12/20/0211:43 AM
It would also make good sense to have double pole switched socket. Recent case in Ireland where boiler connected to a single pole switched socket. Plumber decides to have a go at electrical fault on burner. does not withdraw plug but switches boiler "off" using switch on socket. Fatal!
The legislation in UK re: plug tops is the Plugs and Sockets Regulations 1994. These Regulations require that all domestic 230 volt equipment for sale in the UK must come fitted with a plug top fitted by the manufacturer.If the appliance is from outside UK it must be supplied with euro-plug.
Re: A world standard plug system???#135049 12/20/0203:31 PM12/20/0203:31 PM
I thought this subject would elicit some good discussion and highlight some common practices and habits across the globe.
Addressing classicsat first, the UK receptacles/outlets/sockets are flush fitting unlike the Euro types that are recessed. I can see why they are recessed – keeping fingers away from the pins and for support – but coming as I do from countries where outlets are flush with the wall (UK, South Africa, USA) the recessed types look – how can I say it? – ugly. The French Euro sockets with their pin sticking out are even more so – I suppose it’s what you’re used to. When I discussed 230V for domestic America, my tongue was stuck firmly in my cheek and I was referring to a system with 230V potential between a single phase and ground (à la Europe), hence my references to polarization. I know that present NEC/CEC 230V systems are Edison Circuits and are thus inherently non-polarized.
This brings me to SvenNYC’s and C-H’s comments regarding polarization. The non-French Euro plug is totally un-polarized even with a grounded plug. Even the French type appears to accept the common thin two pin un-grounded Euro plug. It seems common across the Continent that polarization is a non-issue - yet most switching on equipment will be single pole. I would much prefer to switch the phase/live/active conductor, than the neutral/grounded one. I refer to lyledunn’s tragic observation above – though mis-wiring appears to be a contributory factor in that fatality (I must say that not removing the plug was the main one). Is this lack of Continental sensitivity to polarization due to electric history? – were your early 220V circuits all Edison Circuits like North America or taps from 3-phase 127V and therefore non polar by their very nature.
PaulUK has made the observation in the past that the French, whilst having a semi-polarized system are not too fazed which way round they wire their sockets! I know that there is a lot of equipment out there that really doesn’t care which way round it is wired but there are some things (bedside/coffee table lamps) where - for safety’s sake - the live wire should be switched, especially those Edison Screw type bulbs that are common on the Continent. Childrens’ deaths have been reported from here in the US due to touching the live shell of an old un-polarized lamp on 115V. These lamps are often not grounded – so it’s not a grounding issue; which brings me to C-H’s point (7) – could you clarify this for me please.
If the IEC 60906-1 system includes two pin plugs there is still no polarization, hence my liking for the Australia/New Zealand approach. C-H the blades of these are solid brass and quite sturdy. I have not managed to casually bend one, unlike the common NEMA 5-15! Interesting C-H that you say this is the world standard for 115V systems.
Trumpy - a dedicated 240V 20A circuit and receptacle. The plug is a 240V 15A one which, in case you are unaware, has its phase/active pins horizontal rather than vertical (its 115V counterpart). Could you describe please your 15A socket and plug. I have only seen 10A ones in my wanderings round your neighbour’s part of the world. I noted at the time of my visit the lower maximum wattage on the kettles.
Coming back to the question of the cord exit direction, I see the Swiss plug has it coming straight out the back. I am not keen on this even though this is the rule rather than the exception here in the States. The IEC 60906-1 one, I see, is similar but can have it coming out sideways (but not down apparently). I must confess to not being in favour of pulling a plug out by its cord and most equipment instructions one reads discourage it. As I have said in these forums before, as a child in the UK these “no-pull” instructions always confused me, because with UK plugs this was nearly, physically impossible!