I'll start a new topic, although the subject ties in with the previous discussions concerning plugs and sockets.

There are about a dozen different plugs in use in the world, not counting different manufacturing tolerances in different countries. Even if a new standard plug is introduced, old sockets will remain in place and in use for at least half a century. People and goods are becoming increasingly mobile, although we shouldn't expect an explosion.

This means that the already extensive use of travel adapters will increase further. Unfortunately, travel adapters is the last field where rules for electrical safety are lacking. Either the authorities look the other way if it says travel adapter, or they ban them altogether, creating a "grey" market.

Both manufacturers and users of these adapters seem to accept the unsafe products sold today. These adapters also reinforce the image of poor electrical safety outside your own country.

If we accept that the traveller is not going to buy a suitcase of adapters, which features should a general purpose travel adapter have?

I can think of the following:

Protection from electric shock

The input side of the adapter should be designed to prevent the user from receiving dangerous electric shocks from live parts, such as the prongs. As it has to be compatible with existing sockets, the only options are sleeved pins and a design of the adapter that makes touching of live pins difficult.

The output side also needs to protect the user from electric shock, something which can be achieved by:
- User operated switch, switched on when the plug is inserted
OR
- Residual current device, cutting power in case of fault
OR
- Collar around the holes. This is incompatible with many plug types.

The adapter should also prevent the user from shock hazard arising from the bypassing of earth, which is a common feature of many adapters. This can be achieved by
- Having both input and output sides protective earth, but this rules out a general purpose design. (There are more earthed plugs than unearthed)
OR
- Preventing the insertion of earthed plugs on the output side. This limits the usefulness of the adapter.
OR
- Featuring a residual current device.

Protection from electric fire

On the input side, the risk of fire arises mainly from overloading of the socket and/or poor fit between current carrying pins and socket. With different manufacturing tolerances and socket ratings in different countries, the possible methods of protection are:
- Overcurrent protection from fuse or thermal breaker
OR
- Overheat protection, acting on overheating of the pins. (60-70°C)

The adapter in itself must be safe from fire, which can be achieved by:
- Sizing of current carrying parts to match highest likely current, 20A.
OR
- Fire resistant material
OR
- Overload or overheat protection and depending on the design, possibly also short-circuit protection.

The output side must prevent the attached plug, cord and appliance from short-circuit. This can be achived by fuse or electromagnetic breaker.

Futhermore, preventing the use of appliance on incorrect voltage or frequency reduces the risk of both fire and damage to equipment. As plug designs do not match voltages or frequency, the only ways of achieving this are:
- Indicating the voltage and/or frequency coming out of the socket, having the user determine the suitability for the appliance.
OR
- Having a setting on the adapter, which only allows current to flow when the voltage and frequency is within the permissible range.


[This message has been edited by C-H (edited 03-25-2003).]

I've seen some scary adaptors. In Europe the EU should really have passed directives setting minimum standards for these things. I've seen some very scary universal adaptors that should be outlawed.

There are some good quality Schuko to BS1363 adaptors on the market that seem to pretty much mimic a german outlet perfectly and have proper fusing etc and a sturdy BS1363 front end..

I can't say the same for BS1363 to Schuko adaptors. Most of them don't complete the grounding properly, fall out of sockets and are generally just very poor quality.

The safest way to travel around europe is to buy a good quality trailing socket (single or double) with your home country's outlet on one end, good quality cable in the middle and the other country's plug on the other end.

I've seen plenty of recently sold adaptors that get very hot when used with irons and hairdryers (for various standards) as they're totally under rated and prob. never had their rating tested.

Also seen lots of adaptors that wont fit a recessed schuko outlet even though that's what they're supposed to do. BS1363 with unsheathed pins too!

Is adaptor British English and adapter American English? Living is learning...

Oxford English Dictionary (British) appears to favour Adapter but also has Adaptor as an alternative spelling. It's a bit like '-ize' and '-ise' suffixes - both acceptable to the OED. It favours the former but does note that "s" comes easier from the pen! Favor like color is definately a US adaptation.

djk said ...

"I can't say the same for BS1363 to Schuko adaptors. Most of them don't complete the grounding properly, fall out of sockets and are generally just very poor quality."

Ahhaahh!! ... says Hutch.

Could this not perhaps be a function of the original design of the socket/plug system??!!

Hutch (brought up on BS) dives for cover ...



[This message has been edited by Hutch (edited 03-25-2003).]

Yes it is, but not in the way you think. It is instead a result of trying to design a adapter that fits all continental sockets. The different continental sockets seem to have a common ancestor, the flat two pin socket, something which the adapter manufacturers make use of. Excluding the ground and using thin pins (4mm) does the trick.

BS 1363 and the various modern european standards are all pretty sturdy and safe connectors. Those half baked adaptors are totally unacceptable and should be banned. They're basically "hacks". Many of them are made by very unreputable manufacturers or are completely unbranded. I doubt a quality maker like MK or GE or whoever would produce such rubbish.

The BS 1363 to Schuko adaptors i've seen try to get the earthpin to contact the earth springs in the schuko socket.. a VERY shoddy sollution!

The other major problem I see with adaptors is the massive growth in the use of mobile phones etc all of which have heavy xformer-plugs. People take these things on vacation and they often are too heavy to work with an adaptor. A BS 1363 xformer plug will work fine and be held firmly in place by a BS1363 socket but when you plug it into one of those dodgy schuko adaptors it will usually fall straight out of the wall.

The only sollution is to provide adaptors with a moulded on schuko plug and a BS socket on a short cable or visa-versa.. The same sollution for Italian/Swiss/Danish and Australian systems would work fine.

Or alternatively:

Plug to standard 16amp IEC connector (kettle lead style) and make various sockets with IEC connectors.. (IEC - schuko, IEC - Australian, IEC - BS1363, IEC - BS546, IEC - Italian, IEC - Israli, IEC - Swiss, IEC - Danish, IEC - French) I think that would cover everyone!

Seriously guys, you've both said it in different ways but stuff doesn't fall out of a safe, secure and polarised BS 1363. It was well designed from scratch and was not a compromise over many (slightly different) standards then in use unlike the Euro systems and their adaptors appear to be right now. If it wasn't for the ring main, even the fuse would not be required and detract from the all-round robustness of the BS system. The necessity for a 3-pin plug - even on class two equipment - is a [light] cross that it must bear. It is in part for this reason that I advocated a universal system based on the antipodean standard thus...




with the rationale at...

https://www.electrical-contractor.net/ubb/Forum9/HTML/000167.html

The quest continues ...


[This message has been edited by Hutch (edited 03-26-2003).]

This is from 1988, but it plainly illustrates the problem of shoddy adapters, many of them sold by "reputable" companies like Radio Shack:

http://www.cpsc.gov/cpscpub/prerel/prhtml88/88070.html

[This message has been edited by SvenNYC (edited 03-27-2003).]

The spelling adaptor seems have been standard with many British manufacturers in the past, including MK Electric. I have many MK adapters for various BS546 configurations dating from the 1940s/1950s, and they all use the -or spelling.

On the -ize vs. -ise alternates, the -ize form is actually the original. I have an old 1890s dictionary (British) which doesn't list the -ise variants at all. The King's English dictionary of the early 1930s lists only -ize forms in the main body, but includes -ise variants in the addendum and notes pages. Many people here these days seem to have grown up using only the -ise forms, I've even heard people complaining that -ize is "America corrupting the English language!"

It's like the people who regard "zee" in place of "zed" as an "American corruption," but don't realize that both forms were in common use in England back in the 17th century. Somehow, zee became the preferred form in America while it dropped out of use in Britain. Ditto center vs. centre, and so on. Apparently both forms were common here in Shakespeare's time, but the spread of the printed word resulted in British standardization on -re and Noah Webster's influence meant that the -er form became dominant in America.

Hands up all those Brits who object to the use of the word "gotten" as an Americanism. Sorry, but it was the correct form in British English years ago. There are many instances of words/phrases/spellings where America has retained the original form and it is actually Britain which has corrupeted it since.

Back on topic.....

[This message has been edited by pauluk (edited 03-27-2003).]

Some of the travel adapters sold really are of very poor design and build quality.

It's certainly a good point about using plug-transformers which these adapters. A European-to-British adapter already has quite enough weight hanging on the end of with just a standard BS1363n plug, nevermind anything extra.

I'm not a fan of these all-in-one plug and xfmr combinations that have become so popular. I'd much prefer to have the power pack connected via a regular cord and plug.

Certainly for travel needs, I much prefer a plug-cord-socket home-made adpater to the various combo units on sale.

Some of the newer mobile phone plugs are very neat & light weight whatever they're using to step down the voltage.

I just noticed a weird British connector product.. found an iron with a very old MK BS1363 plug complete with a switch on top of the plug!

Switched Schuko plugs are rare, but they do exist. I use them to cut power to wall warts without unplugging them. They're rather bulky angle plugs with a simple double pole key switch. Nice arcs.

Luckily, the heavy transformers will be gone in a few years. The switching mode power supplies are becoming cheaper and better.
They are lighter as there is no iron core in them. With sufficiently high frequency any material for the core will do. Many aftermarket power supplies sold in Sweden today are of this type. As they are made in China, I suspect it is not a local phenomenon.

But SMPS devices will not work well with certain portable radios or TV sets.

SMPSs toss out a lot of RFI....so I guess for these devices the transformer-based adapters will still be needed (unless they go back to incorporating the power supply inside the radio).

Sven,
this used to be a hurdle, but it has been overcome. The EU has strict limitations on the electromagnetic compatibility. Just about every after-market cell phone charger had to be taken off the market after a "raid" testing the compliance two years ago.

Time to bring this up again!

David had an idea about IEC connectors as an intermediate step in an adaptor. I gave it a little thought:

Here is the idea:

1.) A proper listed/approved local plug (NEMA, Schuko etc.) with grounded 10A 250V / 15A 125V IEC 320 connector on the other back.

You can buy this type of adaptor already:



These are compact compared to conventional adaptors.

2.) The second part is simply a conventional trailing socket with two or three sockets. Listed/approved of course. Instead of the ordinary plug, it has an IEC connector on the cord which mates with the adaptor.

3.) If you have a transformer this is simply connected between the adaptor and the trailing socket. It has a cord with a male IEC connector as input and a female IEC connector on the transformer itself where you plug in the trailing socket.

4.) There is an ungrounded IEC connector too, although rarely used. This should be used on ungrounded plugs. Either you use a trailing socket that only accepts ungrounded plugs or you add an ungrounded IEC to grounded IEC adaptor. It would simply consist of an RCD/GFCI and the connectors. Even with the RCD it can be made very small and robust.

The result? A system where the grounding can't be bypassed unless you have ground fault protection. In addition, you have two or three proper sockets to plug into. Lastly, the plug you insert into the foreign socket fits correctly and is lightweight.

As a bonus, you have a modular system that can be sold in any country of the world. Only one type of transformer is necessary for the whole world: 115/230V Step up/step down. (Still in different sizes, of course)

Ever see a modern Apple power supply for a laptop or an iPod or even their new plug-in wifi stuff.

A small figure-of-eight connector moulded onto a plug slots neatly into the top of the plug-in switch mode transformer. All looks very slick and neat and as you travel around you simply swap the plugs.

The nema setup: the BS1363 setup is bulkier looking!




Similar idea to the IEC adaptors though.

[This message has been edited by djk (edited 06-27-2004).]