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Posted By: djk Polarise schuko? - 09/03/03 11:22 PM
I was just thinking, for safety reasons schuko isn't exactly the best design of outlet as it's unpolarised. However, there is a very simple sollution.

1) Drop CEE 7/IV (Schuko) and replace with the compatable CEE 7/V (French) which is polarised when used with grounded plugs and pretty much fully backwards compatable with normal CEE 7/VII plus which allow for both grounding options.

2) make non grounded europlugs include a small moulded protrusion on one side, big enough to not fit past the french grounding pin but still compatable with old schuko and italian/danish/swiss outlets.

Basically a europlug with oneside bulging out.

This would prevent it from being inserted the wrong way into a French style outlet.

(Recessed swiss outlets wouldn't be a problem as you could pretty much make the bulge the same shape as a grounded swiss plug, just without the 3rd prong)

[This message has been edited by djk (edited 09-03-2003).]
Posted By: C-H Re: Polarise schuko? - 09/04/03 08:47 AM
More importantly the CEE 7/V socket is less prone to damage and offers better resistance to water. I'm with you.

And require that all grounded plugs are CEE 7/VII.
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2) make non grounded europlugs include a small moulded protrusion on one side, big enough to not fit past the french grounding pin but still compatable with old schuko and italian/danish/swiss outlets.

My 'neoplug' - ungrounded version - meets this critireon. [Linked Image]

A more important feature of the protrusion or assymetric body is that it prevents insertion into 2.5A sockets. This allows a 16A rating without risk of fire.


[This message has been edited by C-H (edited 09-04-2003).]
Posted By: djk Re: Polarise schuko? - 09/04/03 02:32 PM
I just think it's a very simple and much less expensive sollution to the whole problem of polarisation in Europe. It would be as easy to implement as the US polarised plug was.

The exsisting sockets wouldn't have to change, the French & Belgian system would become fully polarised and eventually, over say 20-30 years the non-polarised plugs would simply slip out of use.

Denmark and Italy might even jump on board even although I can't see the swiss or british/irish systems changing for a LONG time.
Posted By: C-H Re: Polarise schuko? - 09/04/03 03:29 PM
The question is why you would want a polarised plug. Exactly what is it good for?
Posted By: SvenNYC Re: Polarise schuko? - 09/04/03 04:16 PM
In the case of table lamps, a polarized plug is usefull because (assuming everything is wired properly), the switch will be on the "HOT" side, which leads to the center contact.

The metal screwshell is then the neutral and this part will not accidentally become "live" if the plug is reversed.

This way, if the lamp is without a bulb, but still plugged in, an idiot will not get a shock from sticking his or her finger in the lampholder.

Of course for my own use, I think these things are an annoyance and I always curse whoever came up with these damned things. Sometimes I've replaced the plugs with standard ones.

However when I rewire and replace the lampholder on an old table lamp or attach a new cord on an appliance for a relative or friend, I ALWAYS connect the conductors to the proper screw terminals on the lamp socket and screw on a polarized dead-front (totally enclosed) plug, or use a cordset with a moulded-on polarized plug and make sure the switch is on the live side.

It protects me from anyone yelling at me because they got bitten by doing something stupid. [Linked Image]

[This message has been edited by SvenNYC (edited 09-04-2003).]
Posted By: C-H Re: Polarise schuko? - 09/04/03 04:28 PM
I think that is a problem that should be adressed by redesigning the lampholder.
Posted By: djk Re: Polarise schuko? - 09/04/03 05:26 PM
Polarised plugs make a lot of sence. Schuko was designed for supplies that used 127V to make up the 220V supplied to the applience. Both terminals were hot, same with the Italian system.

However, with the use of 230V + Neutral bonded to ground it makes no sense not to polarise the plugs!

Most appliences use single pole switching so when the plug has the blue wire on the hot side the applience parts remain live. Light sockets are an obvious danger. Fusing on the neutral side is also considered dangerous and may result in a non polarised system.

I just think it would be a general safety benefit and very easily achievable situation.

I also fail to see why we need to have CEE 7/IV and CEE 7/V. It's just unnecessary duplication and I think the CEE 7/IV (schuko system) is inferior in this instance. The French version is the obvious candidate for a replacement. Lots of advantages.. it's less complicated, more robust, polarisable, fits the same plugs, takes up the same space and can easily fit into a shucko box.
Posted By: pauluk Re: Polarise schuko? - 09/04/03 08:06 PM
Polarization of plugs seems to be of far greater concern to the British/Irish committees than in Continental Europe. Even though the French receptacles are polarized, many electricians don't seem too worried about which way they wire them anyhow.

The ironic thing about the lampholder question is that the U.K. -- with its insistence on polarized plugs -- has the double-contact bayonet holders in most table-lamp applications.

There are cases where polarization of the plugs is desirable, but I think that in some instances the case is overstated. If the plug on, say, a portable drill or a kitchen blender is reversible, it doesn't really matter.

(OK, fellow Brits, go ahead and call me a traitor... [Linked Image]).
Posted By: SvenNYC Re: Polarise schuko? - 09/04/03 08:19 PM
The last blender (a Waring "Blendor") I changed the (crumbling) flex on didn't have a polarized plug on it.

I used a polarized cordset. Wired the thing so the switch was on the hot side. The casing was metal.

You're right. I don't understand what the purpose is.

I personally think it's the Chinese manufacturers' fault. They all seem to think that ALL UL-Listed cordsets MUST be polarized - and that's pretty much all you can find these days...so by default...guess what. [Linked Image]

I once wrote UL asking why they insisted on polarization of double insulated and transformer-equipped devices like cassette players and clock radios.

The reason they said is because of fusing. Some of these devices actually have a safety fuse inside....so they want the fuse on the "hot" side, I guess. And it's true. One boombox I opened up had a miniature glass fuse snapped in a clip on the PC board that held the transformer and the rest of the power supply components.

[This message has been edited by SvenNYC (edited 09-04-2003).]
Posted By: djk Re: Polarise schuko? - 09/04/03 09:04 PM
yeah most british lampholders will electrocute you no matter which way you stick your finger in!

The lesson being: don't stick your finger into a lamp holder!

I still fail to see why lamps can't have 2 pin connectors on the bottom.

Thermal expansion must have been an issue in the old days. Although edison screw fittings are terrible for that. if the bulb connector expands you're really jammed in!


[This message has been edited by djk (edited 09-04-2003).]
Posted By: pauluk Re: Polarise schuko? - 09/05/03 10:00 AM
The safety groups have made ever stricter rules about plugs and sockets (shutters, partially shielded pins on BS1363 plugs, etc.), yet the lampholder remains pretty much the same design as it's been for many, many years (odd items such as MK's type with the isolated pins notwithstanding).

I don't believe there's anything basically wrong with lampholders, but it's rather curious that the normally over-zealous committees don't seem to have turned their attentions to it as yet.
Posted By: djk Re: Polarise schuko? - 09/05/03 12:19 PM
Well our overzelous committee seems to be about to go on a mad RCD spree. They're reviewing the RCD requirments with a view to making them much tighter. A single RCD on the panel won't do.
Posted By: SvenNYC Re: Polarise schuko? - 09/05/03 02:13 PM
Aside from cutting the current flow to both contact pins when the bulb is removed, how else can you redesign a lampholder without upsetting the entire existing lightbulb industry and p---ing people off when they have to go out and buy new lampholders to accomodate the new types of bulbs?

A neat lampholder would be the bi-pin plug-in CFL sockets (the little U-Tubes for some table lamps) with a few minor modifications (recessing the contacts in even deeper and maybe shuttering them).

Or how about something that twist-locks (like the NEMA type Twist-Lok plugs used in the 'states)? That way the bulb won't fall out when flipped upside down.
Posted By: C-H Re: Polarise schuko? - 09/05/03 04:37 PM
Sven et. al. Didn't we have a discussion about improved lampholders some time ago? A new and better type would indeed be a good idea.

djk,
I noticed that the manufacturers are now pushing for the RCBO. Or from a rule makers point of view: One RCD per MCB. I think it's a good idea hadn't it been for the price Strange: A (portable) RCD costs less than €10 and a breaker €5. But integrated into a RCBO the price jumps to €50!

Concerning the polarisation: Millions of 230V line-to-line socket will remain in use for years to come. And there must be hundreds of millions of unpolarised sockets in use today.

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I also fail to see why we need to have CEE 7/IV and CEE 7/V. It's just unnecessary duplication and I think the CEE 7/IV (schuko system) is inferior in this instance. The French version is the obvious candidate for a replacement. Lots of advantages.. it's less complicated, more robust, polarisable,

So far I agree!

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... fits the same plugs,

Appliance plugs fit. Not extension cords or plugs fitted by the user. You would have a very hard time finding a rewireable plug that fits French sockets here.
Posted By: JohnS Re: Polarise schuko? - 09/05/03 04:38 PM
Other than for lamp sockets, what other reason would an AC system need to be polarised?

The US started polarising the non grounded two conductor appliance cords a few years back by making one blade wider than the other. and that was primarily done for lamp safety.

But, with both conductors being the same colour, it is a 50-50 chance that the wires are connected properly anyway. And for sure if a lamp owner replaces the socket, there is no guarantee the connections will be correct afterwards. So, what is really gained?

If I'm not mistaken, lamps don't use the Schucko plug anyway, they use the smaller europlug. So, why modify the schucko plug just for lamps? If safety is a concern with the lamps, then it is up to the lamp manufacturers to come up with a safe lamp socket. That for sure would be cheaper, no?
Posted By: Texas_Ranger Re: Polarise schuko? - 09/05/03 05:03 PM
Only one single word about portable lamps: double pole switches!
And voila the only solid argument for polarised plugs deflates like a car tyre.
Another thing, I think with BS1363 shielded pins and shutters are indeed a good idea. Old BS1363 plugs were indeed quite scary as you have to grip them pretty close to the pins when pulling them out. And the holes in the socket are awfully large.
Posted By: C-H Re: Polarise schuko? - 09/05/03 06:39 PM
Lamps that come from the factory are fitted with the Europlug. However, lamps that have been rewired by the user have Schuko plugs or the old round plug, since there is no rewireable and ungrounded plug for double insulated appliances. Europlugs are always moulded with a cord. I would think this legal requirement is intended to prevent people from using an ungrounded plug on a grounded cord.

There are some national plugs that are rewireable and look like the europlug, e.g. the French 6A plug or Italian 10A plug.
Posted By: SvenNYC Re: Polarise schuko? - 09/05/03 08:00 PM
C-H said:

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lamps that have been rewired by the user have Schuko plugs or the old round plug

They still sell those old round plugs? Hmm...

I'm sure replacement Europlugs have got to be sold in _SOME_ place. There's a company in Spain that maufactures them and a few others (don't know the names since they only stamp a logo on the housing).

Anyway, here in New York City (of all places!) two lighting stores sell replacement Europlugs. It's a little clamshell that snaps together.

I've never bought one so I don't know how the wires attach to the pins. Why would anyone buy a Europlug in the states (unless you're weird like me [Linked Image] )?

I have another replacement type Europlug that is non-rewireable. The pins get crimped onto the lampcord and then the entire assembly gets snapped into the housing. I used one of these on the flex of an old 120/240 volt Philips portable radio.

[Linked Image from interpower.com]

Of course, once you attach one of these plugs and then in the far future it comes time to replace the cord, you can't reuse the plug and attach it to the new length of flex....a total waste.

Also, why would someone use a two-ping plug o n a grounded cord? Usually the three-wire cord is much thicker than what could fit in the hole of the housing of a replacement Europlug.

But then again...the fools that would do that are the ones that use a molded plug with a few inches of flex stump and splice it to the cordset of their appliance with black tape -- they don't want to spend minimum $3.00 for a three-pin heavy-duty plug.

[This message has been edited by SvenNYC (edited 09-05-2003).]
Posted By: Texas_Ranger Re: Polarise schuko? - 09/06/03 11:22 AM
My electrician told me the crimp-on Euro plugs have been outlawed years ago here in Austria but didn't give me reasons. I suspect some bloody idiots didn't crimp them on but just stuffed the wire into the holes and naturally the assembly eventually failed. I still have 1 or 2 unused ones around, they were sold in black, brown and white, male and female.
Rewireable Euro plugs are illegal for some really weird reason, one reason is supposed to be that plugs for double insulated appliances must not have any exposed screws ('cause these screws would have to be grounded and then it isn't double-insulated any more yadda yadda yadda... For the same reason it's illegal to fit a Schuko plug to a device with Euro or contour plug. The only legal way is to buy a new cord with molded plug. However I doubt _anyone_ really sticks to that piece of code. At least it's good for week-long discussions at de.sci.ing.elektrotechnik).
These crimp Euro plugs easily accommodate round 2x1mm2 flex, so it would be easy to fit 3x0.75mm2 flex which is even thinner.
Reminds me of a story. I once bought a 1949ies vintage vacuum cleaner.At the first lokk I thought they simply spliced a pice of flex with a Euro plug to the old rubber cord. however, a closer look revealed they had done much better than that. They had cut the old rubber cord about 30cm from the appliance connector (the rubber had about the consistency of chewing gum). Then they spliced a short piece of white 2x0.75mm2 flex (twist'n tape, they didn't even bother to tape the neutral splice seperately, they taped the black splice, then did the blue-grey splice and taped the entire splice). Then they spliced the white cord to a long piece of 3x1mm2 flex (same method). Finally they spliced the black cord to the reamainder of the white cord which had a molded Euro plug. AARRGH! How stupid can people be? To think they could have saved 3 (!) spliced if they had just connected the 3x1mm2 cord to the appliance plug and fitted a new plug!
Posted By: pauluk Re: Polarise schuko? - 09/07/03 12:50 PM
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They're reviewing the RCD requirments with a view to making them much tighter. A single RCD on the panel won't do.
It's no secret that I'm a not a fan of the whole-house RCD approach. I would much rather see individual devices, like the American GFCI, for each circuit. At the moment, however, the cost of an RCBO makes it a very unattractive proposition for TT systems where every circuit needs RCD protection.

On the polarization issue in general, I think that the British IEE sometimes gets carried away.

Let's look at something like a double-insulated hair dryer or electric drill. The IEE would object to it being run on a reversible plug because a single-pole switch on the unit could end up being in the neutral.

So what? The switch still breaks the circuit and turns off the appliance. Yes, it leaves the motor connected to the hot side of the line, but what does that matter in this situation?

By the way, does anybody know exactly when the polarized two-prong NEMA plugs were introduced?
Posted By: Hutch Re: Polarise schuko? - 09/07/03 01:50 PM
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By the way, does anybody know exactly when the polarized two-prong NEMA plugs were introduced?

On or about 1920 according to my references.
Posted By: Texas_Ranger Re: Polarise schuko? - 09/07/03 05:21 PM
All drills I've ever taken apart had a double pole switch, even the cheap far-east (or maybe not even so far east) rotary hammer.
Posted By: SvenNYC Re: Polarise schuko? - 09/08/03 02:19 AM
Ranger said:

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Rewireable Euro plugs are illegal for some really weird reason, one reason is supposed to be that plugs for double insulated appliances must not have any exposed screws

HAHAHAHAHA!!!!

That must be THE SILLIEST reason I've ever heard.

Why, there's a bunch of companies (one American company in Mexico and a bunch of Colombian companies) that manufactures a line of two-pin plugs where the core containing the screw terminals "snaps" into the vinyl husk. No screws holding the housing together and no exposed terminal screws.

In fact, if you go to Colombia and buy a replacement round rubber plug for semi-heavy duty use, you will get one of those (not the tiny plastic ones for alarm clocks where the two halves of the housing are held with a nut and bolb).

Some Australian plugs are the same way. Taking them apart is difficult -- you have to carefully pry out the core with a small screwdriver.

As far as drills are concerned, I wonder if the double-pole switch is a requirement for CE approval?
Posted By: C-H Re: Polarise schuko? - 09/08/03 09:49 AM
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As far as drills are concerned, I wonder if the double-pole switch is a requirement for CE approval?

I know it's required in at least some standards.

There is a basic principle that appliances should not be dependent on the socket and house wiring: As long as it gets the right voltage and frequency, it should be safe.
Posted By: pauluk Re: Polarise schuko? - 09/08/03 01:46 PM
I think you may be right about the double-pole switching in some current standards.

It certainly hasn't always been that way though. I have several kitchen appliances (blender, electric knife, mixer etc.) made by the French company Moulinex in the 1970s. They are all double-insulated, 2-core cords only, and all have single-pole switches.
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