because BS 546 sockets can only be connected to appropriatly fused circuits and you'd get muppets putting 2A sockets on a 32A ring final. Or 15A sockets on a 6A circuit.
The most basic problem with DIY work
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because BS 546 sockets can only be connected to appropriatly fused circuits and you'd get muppets putting 2A sockets on a 32A ring final. Or 15A sockets on a 6A circuit.
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I too have had problems. particularly with the slanted MK sockets. Tighten one week, go back the next and not tight at all. I have also found terminals (not mine) tightened so much that the screw head had broken. Picking up eric's comment, it is now common for car tightening instructions to state,"torque to x, then turn Y degrees". Whether this would work for electrical equipment with soft metals I don't know.
And the reason they cant do that now is.....?
They can, but if you're designing a modular system then it's different to just providing a screw terminal and a set of MIs. Ideally we would all trust the installer to know what they're doing if they're replacing things, but these days manufacturers, at the very least, "feel" obliged to make things fool proof.
Earliest example I can think of is Wylex standard and it's tab system on larger devices to prevent fitment to the lesser-rated busbars. If that wasn't acceptable (by standards, socially or otherwise) in 196x then it certainly wouldn't be so in 2013.
Easy win is 2A/15A fuse holder in faceplate.
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And 13A fuses in a standard plugtop feeding a 0.75mm cable-lamp, or similar, isn't too clever either. My daughter recently bought a TV set with such an arrangement, provided by the manufacturer.
So the existing (approved) system is far from perfect, or even far from sound.
So the existing (approved) system is far from perfect, or even far from sound.
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Working in metal framed structures with multi motors running as with stone crushers, batching plants, and other heavy industry screws do work lose and it is a real problem.
However in a brick and wood house I would agree there is very little problem.
However the 13A socket is used in both. I will agree the 13A socket was inside the panel but I did have one in every panel to plug my laptop into when running the PLC programs to fault find. Also common to provide for vacuum cleaners and the like.
The problem is the same stuff is used in so many places but at the end of the day do you design stuff to be installed by trained personal or idiots. To my mine the more idiot proof you make anything the cleaver the idiots become at getting round it.
As a demonstration in university I had to make a PLC program to sort plastic farm animals to show school kids what could be done. We considered every way we could of how the animals would be placed on the conveyor. What I had not considered was kids putting one animal riding on another. But they did.
I have seen all sorts of ideas to stop lose screws including varnish and paint which dried then cracked off.
The only real answer is training and one has to expect people who are not trained will make errors it's just a fact of life.
I'm afraid it wouldn't. The "torque to x, then turn Y degrees" model was introduced for head gaskets in the 1980s, and uses torque-to-yield bolts.
The first, torque stage is designed to simply ensure that the head is sitting flat against the gasket, and the gasket to the block. The second and third (angle tightening) stages are then used to create a consistent clamping force between the components, and the bolts are designed to yield at a particular stress/strain to ensure this consistency. Because of this, they also are likely to need replacing on head removal due to risk of snapping on second application.
The presence of oil/grease/artifacts when tightening to torque only means a consistent clamping force is unlikely, and before the days of torque-to-yield bolts, the head bolts were always checked at the initial 1000 mile inspection, after the gasket had 'relaxed' a little.
Whilst this could be applied to electrical screw terminals, i.e. torque down to the copper, then screw down to create a set impression, there are just too many variables IMHO to make this viable, i.e. differences in the copper between cables, bent conductors, etc.
The only way to design electrical terminals effectively to maintain a (reasonably) consistent clamping force is by using spring contacts, which is what MF connections are all about.
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As supplied it should have had a 3A fuse not 13A if it had a 13A fuse then something was wrong.
This is why our system is so much better than in rest of Europe we can fuse down in the plug they have no option.
You know it was wrong, I know it was wrong, but obviously the manufacturer who is authorised to stick a CE mark on the TV set doesn't know it was wrong.
More likely he or she knew and didn't give a damn about safety of the people who would be buying the equipment.
The CE mark has been abused so much by non european manufacturers it is no longer a sign of compliant and safe equipment.
That's certainly true - but, in the present context, I can't see how the presence of a CE mark on the TV (or on the BS1363 plug) can be taken to mean anything in terms of what BS1362 fuse is present in the plug.
Kind Regards, John
Simples:
Make the penalty for importing such equipment 10's of years in prison.
I promise you that importers will stop bringing in dubious cheap tat.
Make the penalty for importing such equipment 10's of years in prison.
I promise you that importers will stop bringing in dubious cheap tat.
It is also common for electrical switch gear manufacturers now to recommend set torque levels in their instructions.
If the recommended torques are anything like those for MCBs/RCDs, I would be a little concerned. As I observed earlier, with MCBs/RCDs, I can often easily get a further quarter of a turn or more by hand after tightening to the manufacturer's recommended torque.
I suspect one of the main problems with recomending tightening torques for electrical terminals is that, unlike most engineering situations, the nature, properties and arrangement of what one is 'tightening onto' [conductor(s)] is not totally defined, constant or predictable. For example, it seems fairly unlikely that the optimum/desirable torque will be the same when tightening onto a solid copper busbar as when tightening onto a stranded conductor,or multiple stranded conductors.
Kind Regards, John.
Just fitted a Hager board and they gave these settings:
http://download.hager.com/hager.uk/files_download/user_instructions/torque-settings.pdf
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