Cyprus-Forum.com

[skyvet]

My wife told me that the locally bought electrical extension lead she was trying to use wasn't working.
I checked the fuse in the plug, and that was ok, so I removed the cover from the extension sockets, and what I saw was horrifying!
Instead of the mains lead being connected to the "busbars" that feed the sockets by terminals, in this case the wires had been SOLDERED on to the busbars! The heat generated had caused the solder to melt, and the connection had failed.
This extension lead carried a BS (British Standard) mark and number, making it appear to be of quality manufacture, but it was potentially lethal!
Please check any extension leads that you have in case yours is the same as mine was!

[twinkle]

Made in China???

[pantheman]

My wife told me that the locally bought electrical extension lead she was trying to use wasn't working.
I checked the fuse in the plug, and that was ok, so I removed the cover from the extension sockets, and what I saw was horrifying!
Instead of the mains lead being connected to the "busbars" that feed the sockets by terminals, in this case the wires had been SOLDERED on to the busbars! The heat generated had caused the solder to melt, and the connection had failed.
This extension lead carried a BS (British Standard) mark and number, making it appear to be of quality manufacture, but it was potentially lethal!
Please check any extension leads that you have in case yours is the same as mine was!

I would have said contact the authorities, but they won't give a toss anyway assuming you could track the correct office to complain to.

Try contacting BSI, give the details and let them do some legwork.

The reason there is so much trash stuff in cyprus, is because there is nowhere to go to complain about it. If there is, it is not obvious to the majority of people.

You should always be suspicious anything electrical made in china!

good luck

[skyvet]

Made in China???

Very probably Twinkle.

[devil]

As an electrical engineer having written books on various aspects of assembly, I can say that soldering is a much used assembly method and is extremely reliable. I would have no qualms about any correctly designed solder joint for carrying currents far higher than 13 A. It is therefore erroneous to vilify soldering. You probably have thousands of electrically conductive solder joints in your house and car, all operating reliably.

So, let's analyse what could have gone wrong here. The first thing that could cause overheating of a solder joint is a current far in excess of that for which it is designed. As a guess, for it to reach liquidus (183°C for a eutectic tin/lead solder), it would require a minimum of 100 A, probably a lot more. This is impossible because, even if the fuse were replaced by a bar of metal, the ring main circuit breaker would trip. This is therefore extremely unlikely.

A second possibility, and quite probable, is that the solder joint was imperfect. For a solder joint to be good, intermetallic compounds have to be formed between the solder mass and the copper of the wire and between the solder mass and the bus. If something inhibited this formation of intermetallics, then there may be a poor electrical contact which could heat up sufficiently to melt the solder. Possible causes for this to happen are heavy oxidation of the metals, contamination of the metals, inadequate plating of the metals or a lack of soldering flux. A post-soldering inspection by a trained operator should detect this.

A third possibility is that soldering flux residues are too corrosive, thinning down the wires close to the joint. This can have a "snowball" effect. Corrosion thins the wires which heat slightly, the higher temperature causes the flux to corrode the wires more, causing a further rise in temperature and so on. High humidities, such as we have had this summer, could exacerbate the problem.

A fourth possibility is that the solder joint was badly designed. If I were to design a solder joint from a wire to a bus, I would have the denuded wire loop sharply through a hole in the bus and then soldered. Alternatively, the bus could be crimped onto the wire and then soldered. If the wire is simply placed along the bus, without any mechanical support, then this would be a poor choice.

A fifth possibility is a manufacturing defect termed a "dry joint". This occurs when a non-eutectic solder is used and the wire is disturbed during the cooling phase when the temperature is between liquidus and solidus. This deranges the crystallisation of the different intermetallic phases and can result in a poor electrical connection.

A sixth possibility is a simple mechanical fault, such as the cable grip being inadequate and too much mechanical stress is placed on the joint.

Now, I wish to ask a couple of specific questions. When did you buy this lead? Does it bear a label or marking ROHS or similar? I ask these because the EU ROHS Directives came into force last year and these specify that solder must not contain lead. These lead-free solders have a higher melting point and totally different mechanical characteristics, including a greater fragility. I work in conjunction with a group determining reliability issues with lead-free solder joints, so this example may be of interest to us. Is there any way I could examine the faulty item?

FYI, the BS or CE mark is not concerned with HOW an item is manufactured. It is concerned with whether it is safe in normal use (high-voltage testing, maximum current testing, shuttering of the sockets etc.). FYI, most moulded BS 1363 plugs have the wires soldered to the pins and the reliability of these is excellent.

I consider it wrong to imply that a soldered appliance is inferior to other methods of connection, rather the opposite.

[sirox101]

made in poplife more like !!! dont buy nowt cheap in cyprus bud the regulations are a joke its cheap for a reason

[skyvet]

Devil,
I appreciate your in-depth and educative analysis which I read with interest. Unfortunately I have disposed of the lead now, so I'm unable to answer your queries regarding the BS number etc. As I have been in Cyprus for over 2 years now, I'm also unable to remember where it was purchased, but I do know that it was purchased locally.
I bow to your superior knowledge on the subject, but it did seem unsafe to me, which is why I made the posting.
Regards

[zan]

I saw this thread a while back and did not get a chance to add something important for extension lead users....

Many people make a huge mistake in not unravelling the whole of the cable from the lead. What they usually do is undo just about as much as they need and then use the lead like that. This is fine when you are using small loads but at higher loads the cable just becomes a coil of electromagnetic currents and will heat up very very quickly. This can be to a point of if a child or someone even picks up the cable it will melt in their hands and the rest I think you can make out for yourselves. Remember this guys...It is very important. The other things that could happen is that the soldered joints could melt....Better that than a burned hand or a fire.

[pantheman]

I saw this thread a while back and did not get a chance to add something important for extension lead users....

Many people make a huge mistake in not unravelling the whole of the cable from the lead. What they usually do is undo just about as much as they need and then use the lead like that. This is fine when you are using small loads but at higher loads the cable just becomes a coil of electromagnetic currents and will heat up very very quickly. This can be to a point of if a child or someone even picks up the cable it will melt in their hands and the rest I think you can make out for yourselves. Remember this guys...It is very important. The other things that could happen is that the soldered joints could melt....Better that than a burned hand or a fire.

Zan, i think he was referring to an extention block on a short cable rather than the reel that you are referring to.
Also to get to the pint of melting the pvc, you would need a very heavy load for a period of time to achive this. Have never seen this in practive, but i would suspect that domestic electrical installations wouldn't allow such a large load without a fuse or trip going.

Notwithstanding this, it is always advisable to un-reel all of the cable anyway.

Cheers

[zan]

I saw this thread a while back and did not get a chance to add something important for extension lead users....

Many people make a huge mistake in not unravelling the whole of the cable from the lead. What they usually do is undo just about as much as they need and then use the lead like that. This is fine when you are using small loads but at higher loads the cable just becomes a coil of electromagnetic currents and will heat up very very quickly. This can be to a point of if a child or someone even picks up the cable it will melt in their hands and the rest I think you can make out for yourselves. Remember this guys...It is very important. The other things that could happen is that the soldered joints could melt....Better that than a burned hand or a fire.

Zan, i think he was referring to an extention block on a short cable rather than the reel that you are referring to.
Also to get to the pint of melting the pvc, you would need a very heavy load for a period of time to achive this. Have never seen this in practive, but i would suspect that domestic electrical installations wouldn't allow such a large load without a fuse or trip going.

Notwithstanding this, it is always advisable to un-reel all of the cable anyway.

Cheers

Just thought I would tell the dangers of leads and it was not a direct comment on what happened.

Have you ever tried to leave an extension lead coiled and run near to the 13A limit that it can take....It literally takes seconds for back EMF and Eddie Currents to raise the temperature and create even more heat. It works just like a super heater in giant factories. Giant coils can induce heat in metal in less than second that will burn your hand off.