RS Components order FAIL / UK plug discussion - Page 1
Forum section: electronics / general

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 05:39:47 pm
content: A while ago my dad ordered me a Raspberry Pi (http://raspberrypi.org) ARM linux board (Dave likes to call it a dev. board although that's not its intended function...) from RS components, one of the Raspberry Pi Foundation's partners.Seven weeks or so later we get a package containing everything we ordered - The RPi itself, an ethernet cable, an HDMI cable and a wall wart.The problem was that they had sent us a wall wart with a European plug, and we live in Scotland so this was completely uselessFail No. 1:I watched as my dad ordered, it definitely had a picture of a UK plug. The invoice was marked with a euro plug however.Fail No. 2:We emailed RS explaining the situation. They offered to send us the correct wall wart, and told us we could keep the European one.They mailed usanother European one.Fail No. 3:We emailed again, explaining the situation. They apologized and put it down to a problem with communication inside the company.They asked us to send back the two European wall warts (which we did) and said they would make sure to actually send a UK wall wart this time.They then sent the whole lot again - another Raspberry Pi, more cables andanother European wall wart.I'm not sure whether or not to complain at the last one or just to keep the lot... They're clearly incompetent.Ah well... At least I can use my phone charger, since they're using micro USB for power.David.

author: Short Circuit
author_rank: Frequent Contributor
timestamp: July 31, 2012, 06:01:56 pm
content: Clearly something wrong with UK electrical utility system

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 06:08:12 pm
content: Quote from: Short Circuit on July 31, 2012, 06:01:56 pmI'd argue that the design of our (UK) plugs + sockets is among the safest in the world!Edit: And possibly the most painful to stand on! The pins tend to end up facing upwards if you drop the plug on the floor.

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 06:20:30 pm
content: Quote from: DavidJRobertson on July 31, 2012, 06:08:12 pmI want to hear why you would think that.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 06:42:16 pm
content: Quote from: chrome on July 31, 2012, 06:20:30 pmOkay, here goes:All plugs have a earth pin. Although it is sometimes plastic (in the case of "double-insulated" devices), it is always present. Being slightly longer than the live and neutral pins, it is inserted first, moving a spring loaded plastic shutter mechanism which covers the live and neutral holes - so nothing can be inserted in to them accidentally/by a child/whatever. As, in many other countries, not all plugs have an earth pin, it is not possible to do this as non-earthed plugs would be unable to be inserted.The live and neutral pins also have a plastic covering on the part of them closest to the plug body, so that only the tip of the pins is exposed. The sockets are designed such that the pin will not connect until the plug is inserted past this point. This means that you cannot accidentally touch anything dangerous as the plug is partially inserted, as by the point that the pins actually connect, all of the exposed pins is coated in insulating plastic. With (some) US plugs(as an example), it is trivially easy to touch the pins as they are partially inserted, especially by angling the plug, which is possible because of the design of the sockets combined with the fact that the pins are punched from relatively thin sheet metal.Our plugs are polarized (unlike, for example, US and European ones). This gives a safety advantage - if the appliance is switched, the switch will always be on the live conductor. This is safer because when the switch is off, there will be no live exposed points in the product - take a toaster as an example: When it is off, one end of the element will be connected to neutral, and the other floating (since the switch is off), so shoving your fingers in there and touching the heater won't result in a shock. If it was connected to live at one end - not so much... Also note that the vast majority of our sockets have integrated switches.Allof our plugs have integrated fuses, unlike some other countries. (although this of course relies on the user to use the correct type of fuse)The majority of our plugs are moulded on to the cable (I realize this is the case in many other countries too) and cannot be opened and tampered with or plugged in while opened or whatever this week's brand of idiots think it's a good idea to do.Is that enough convincing?David.

author: tom66
author_rank: Super Contributor
timestamp: July 31, 2012, 06:48:46 pm
content: In addition, a very clever design feature of UK plugs: If the cord is tugged on, and the wires are pulled from the plug, the live wire is always the first to disconnect, then the neutral, and finally the earth.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 06:50:55 pm
content: Quote from: tom66 on July 31, 2012, 06:48:46 pmOh yes, forgot about that one. But that only really applies to the non-moulded type.

author: tom66
author_rank: Super Contributor
timestamp: July 31, 2012, 07:01:19 pm
content: Quote from: DavidJRobertson on July 31, 2012, 06:50:55 pmMost IEC plugs are molded (figure-8, 3pin earthed 13A), but ordinary equipment is usually non molded it seems. Not sure why...

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 07:07:51 pm
content: Quote from: tom66 on July 31, 2012, 07:01:19 pmBecause most pieces of equipment with fixed flexes have the plug attached after the flex. The same fridge works just fine in France, but they use a different plug!

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:17:13 pm
content: Quote from: tom66 on July 31, 2012, 07:01:19 pmJust had a quick look around the house, and I could only spot two non-moulded plugs: One on my desk lamp, the other on an (unused) figure 8 cable.

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:23:48 pm
content: Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmOurs also have that shutter design although not activated by the earth pin but by the other pin (as in you have to insert both pins at the same time) but it's equally effective.Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmOur plugs are recessed so you also can't touch any pins. and nowadays they also have that "only the tips are metal" thing going on, but not all.Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmMost of ours are also polarized, but this is still an excuse since they should use double pole switches (seriously think about it what if the electrician fucks up etc etc).Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmDon't you have fuseboxes then? This seems a bit overkill but I won't say this is bad.Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmSame here, the only time it isn't is basically when you make the cable yourself.So in conclusion I would say they are good but equally good as ours

author: Nirios
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:31:09 pm
content: Quote from: DavidJRobertson on July 31, 2012, 06:42:16 pmThat's how kids learn in the US. "Don't put things into Mr. Sparky's eyes."

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:33:43 pm
content: Quote from: chrome on July 31, 2012, 07:23:48 pmOkay, most of yours are,allof ours are.I agree with you saying that double pole switches should be used.Quote from: chrome on July 31, 2012, 07:23:48 pmSome older houses have actual fuse boxes, but the majority of houses have circuit breakers on each circuit as well as one master RCD/GFI.Plus, I don't think it's overkill at all. It is entirely possible that an appliance could draw an unsafely-high current, while still not tripping the breaker (since this is rated for a very high current as it's for the whole circuit).

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:38:31 pm
content: Quote from: chrome on July 31, 2012, 07:23:48 pmI will point out that I said "Among the safest in the world" not "The safest in the world"Plus, this reply further validates my argument:Quote from: Nirios on July 31, 2012, 07:31:09 pm

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 07:42:22 pm
content: Quote from: chrome on July 31, 2012, 07:23:48 pmLook up the ring final circuit and you'll immediately understand why our 13A plugs are fused.

author: IanB
author_rank: Super Contributor
timestamp: July 31, 2012, 07:48:02 pm
content: Quote from: chrome on July 31, 2012, 07:23:48 pmThe reason UK plugs must have fuses is because the appliance flex is rated up to 13 A but the circuit behind the wall is typically rated at 30 A. The plug fuse is needed to protect the appliance cord.

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 07:54:36 pm
content: Quote from: Monkeh on July 31, 2012, 07:42:22 pmI've only come across negatives for that kind of circuit.Quote from: DavidJRobertson on July 31, 2012, 07:33:43 pmIt usually doesn't matter though, the only ones that aren't polarized are double insulated devices.

author: G7PSK
author_rank: Super Contributor
timestamp: July 31, 2012, 08:00:34 pm
content: Ring mains are 32 amps in the UK. The only draw back to having ring mains that I can see is if the trip goes a whole floor to the house is very often out. The big plus is if you want to run a welder all you need is a piece of six inch nail to put in the plug or better still an old mig tip.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:07:07 pm
content: Quote from: chrome on July 31, 2012, 07:54:36 pmWhich are?The main reason for using a ring circuit is that, for a given current carrying capacity, thinner (and therefore cheaper) cables can be used compared to a radial circuit.

author: Bored@Work
author_rank: Super Contributor
timestamp: July 31, 2012, 08:11:43 pm
content: In general, almost all of the classic plugs in northern Europe suffer from historic limitations.They are too bulky, because historically they were designed when isolation material was not that good and much less mechanically robust. These days one could build much smaller, lighter socket/plug types. Multiple socket outlets are a pain because of the bulkiness.A bunch of the existing sockets are mechanically too complex. With complexity comes higher failure rates. The British socket being one of these, with the mechanical lock via the earthing pin, or the German with a recessed socket and spring earthing contacts.The insertion/removal forces widely vary for the same socket type, depending on the manufacturer, age, and the phase of the moon. What non of the classic socket/plug types have is an easy insertion, easy release system, with a lock-in-place (but which would make them more complex). This is important for disabled persons and if you have an ageing population.Back to the British system.The requirement for fuses because of the ring wiring is annoying. The fuses are not there to protect people, they are there to protect the kettle lead. Something the normal fuse/breaker does equally good in non ring-wired installations. The fuses in fact give an additional point for tampering (replace it with a nail ...), and it is much easier and more tempting to do so than tampering with the breaker in the panel.The polarized plug gives a false sense of safety. If a switch in some equipment is off it does not guarantee there is no voltage any more present in the equipment. There is at least voltage up to the switch. And if the switch happened to be wired wrongly, switching the neutral, you still have a life circuit. To be on the safe side you have to treat any equipment as if the plug is not polarized. I.e. don't trust the equipment's switch, unplug the equipment.The earth shutter don't make the system idiot proof. It just requires a better idiot. Stick something in where the earth pin goes, and you can stick in everything you like in phase and neutral. And plugs without an earth pin can still have a shutter system. Either requiring a higher insertion force, requiring an equal insertion force being present on the neutral and life entry, or requiring additional mechanical action, like having to twist the plug with the two pins a little bit in the socket. All such systems can be circumvented by a better idiot.Oh, and by the way, Britain, including Scotland, is in Europe, and the British plug is therefore a European plug. No need to bash all European plugs if one European plug, the British one, is so superior.

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:13:01 pm
content: Quote from: DavidJRobertson on July 31, 2012, 08:07:07 pmOn wire breaks in the system and 1 wire has to carry all that current, which since you use smaller wires it can't handle etc etc

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:29:16 pm
content: Quote from: chrome on July 31, 2012, 08:13:01 pmWhat you're really saying is:our system - one wire breaks, reduced current carrying capacityyour system - one wire breaks, the whole thing stops workingSo basically ours is partially redundant, although could have safety issues should one wire break and a particularly high current is drawn.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:31:52 pm
content: Quote from: Bored@Work on July 31, 2012, 08:11:43 pmI would never have guessed ...

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:34:17 pm
content: Quote from: DavidJRobertson on July 31, 2012, 08:29:16 pmI'd rather not have any current then not know there is a problem and possibly burn down the house.At least with no power I know something is wrong.

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 08:35:47 pm
content: Quote from: chrome on July 31, 2012, 08:34:17 pmThings don't break without people tampering with them.

author: DavidJRobertson
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:36:22 pm
content: Quote from: chrome on July 31, 2012, 08:34:17 pmFair point.

author: chrome
author_rank: Regular Contributor
timestamp: July 31, 2012, 08:41:35 pm
content: Quote from: Monkeh on July 31, 2012, 08:35:47 pmYes you are correct, things never break without human intervention.

author: G7PSK
author_rank: Super Contributor
timestamp: July 31, 2012, 09:10:33 pm
content: Most rings will be 2.5mm sq. this is rated at 26 amps clipped, on a cable tray, bunched and unenclosed that means virtually all situations with house wiring in the UK so a ring will carry 52 amps and is normally tripped for 32 amp longer rings will be wired with 4mm sq or 6mm sq rated at 38 and 49 amp giving 76 and 98 amps respectively so if a break in one wire should occur there is usually an ample safety margin.

author: tom66
author_rank: Super Contributor
timestamp: July 31, 2012, 09:16:03 pm
content: The ring main was originally implemented after WWII when copper was in short supply. It has stayed with us for nearly 70 years and shows no signs of going away. Nowadays in my experience most sides are wired with 32A wire so there is ample safety margin if one leg fails.

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 10:49:39 pm
content: Quote from: tom66 on July 31, 2012, 09:16:03 pmThere is no such thing as '32A wire' and no, that is not common practice.

author: tom66
author_rank: Super Contributor
timestamp: July 31, 2012, 10:52:26 pm
content: Quote from: Monkeh on July 31, 2012, 10:49:39 pmI may be referring (inadvertently) to twin-and-earth wire, which is typically rated to around 25 amps. I don't know where I got 32 amps from, possibly confusing it with something else.

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 10:56:05 pm
content: Quote from: tom66 on July 31, 2012, 10:52:26 pmT&E is a type, not a size. Standard sizes of it are 1.0mm², 1.5mm², 2.5mm², 4mm², 6mm², 10mm², and 16mm². Rating is dependent on installation method, and there are other factors in determining cable type and CSA.

author: vk6zgo
author_rank: Super Contributor
timestamp: July 31, 2012, 11:21:49 pm
content: Australian plugs do just about all the things which are quoted as desirable,plus they are simple & robust.Plug fuses as per the British system are only necessary with the ring main system & add extra complexity.Australian power outlets (GPOs) use double pole switches.Our plugs are equally nasty to step on with bare feet,as they seem to swing up & dig into the foot,

author: Monkeh
author_rank: Super Contributor
timestamp: July 31, 2012, 11:26:28 pm
content: Yes, the Aussie plugs are good. That's our influence, you understand.

author: HackedFridgeMagnet
author_rank: Super Contributor
timestamp: August 01, 2012, 12:34:27 am
content: Actually the Aussie plugs are originally American, but they didn't catch on in USA.

author: T4P
author_rank: Super Contributor
timestamp: August 01, 2012, 12:57:55 am
content: Well i have the same plugs here ... a "steamboat" blew a hole in the fuse and the breaker didn't trip ... then again ring mainsBUT i had situations of fuses not blowing before the Circuit breakerBut the safest part is that every EVERY socket has it's own switch so it's ... safe.

author: vk6zgo
author_rank: Super Contributor
timestamp: August 01, 2012, 02:14:20 am
content: Quote from: HackedFridgeMagnet on August 01, 2012, 12:34:27 amThey are very similar to an old US type,but the Australian specification was written locally.One of the Chinese standards is also very similar,except that they put the earth uppermost,which is a better idea.The simplicity of the design allowed Australian manufacturers to embrace modern materials,whereas the complexity of other designs kept manufacturers using bakelite & similar materials until strength & rigidity problems of the newer plastics were resolved.

author: Bored@Work
author_rank: Super Contributor
timestamp: August 01, 2012, 05:30:44 am
content: Quote from: DavidJRobertson on July 31, 2012, 08:31:52 pmSee, you learned something new. Now go out of the house and welcome Europe.

author: G7PSK
author_rank: Super Contributor
timestamp: August 01, 2012, 07:58:39 am
content: Quote from: Monkeh on July 31, 2012, 10:49:39 pmWire goes by size in sq mm. the amp rating varies according to how it is installed laying on the rafters or clipping to a wall allows for a higher current than total enclosure in a conduit with other wires tightly packed around it. According to my chart which I have in front of me, 2.5mm t&e can vary between 18 and 29 amps and 4mm 27 to49 amp. The 32 amps is the usual rating of the ring's mcb.

author: T4P
author_rank: Super Contributor
timestamp: August 01, 2012, 12:02:04 pm
content: What they do with the ring mains here in my town is use 2x2.5mm ... for 32amps

author: G7PSK
author_rank: Super Contributor
timestamp: August 01, 2012, 12:37:20 pm
content: Why not just use 4mm or 6mm.

author: buxtronix
author_rank: Contributor
timestamp: August 01, 2012, 01:16:52 pm
content: Other features of UK plugs which seems to have been missed here...The earth pin is always on top (the L/N are "down" when facing the socket) and is exposed all the way to the plug body (not partially insulated). With the earth on top, anything that happens to fall down onto a partially withdrawn plug and into the gap is likely to sit in contact with the earth pin rather than a live one.Particularly important with metal window blinds falling onto a power point...most other designs risk the blind being made live.Another feature - the cable always goes in at 90 degrees, never straight. This prevents things like furniture pressed against the wall from straining the cable and potentially splitting the insulation. It also discourages pulling the plug out by the cord (which introduces a risk of pulling the wire out of the plug with habitual pulling).What else...ah yes, the flat pins offer greater contact area with the socket electrics, increasing current carrying capacity - the round continental plugs dont allow for much practical contact area, making things hotter.Brilliantly engineered, though from a users point of view, big and unwieldy!

author: Monkeh
author_rank: Super Contributor
timestamp: August 01, 2012, 02:07:09 pm
content: Quote from: G7PSK on August 01, 2012, 07:58:39 amWell aware.Quote from: G7PSK on August 01, 2012, 12:37:20 pmDefeats the purpose. And you try getting 6mm² into most sockets twice. May as well just use a radial.Quote from: buxtronix on August 01, 2012, 01:16:52 pmDisagree. There have been many issues over the years with insufficient contact area and poor contact pressure causing sockets to fail under normal loads. The actual contact area in a BS1363 socket is quite low. Proper round pins (see IEC 60309 for an example) offer far more contact area than the flattened pins of a BS1363.

author: WorldPowerLabs
author_rank: Regular Contributor
timestamp: August 01, 2012, 04:18:33 pm
content: Quote from: Nirios on July 31, 2012, 07:31:09 pmIt's usually a memorable lesson!I'm surprised by how many people remove the grounding prong on our plugs when it gets in the way -- even folks who should know better (like physics professors)...

author: SeanB
author_rank: Super Contributor
timestamp: August 01, 2012, 06:15:08 pm
content: Last week I was busy for a half hour persuading a socket to let go of the plug in it, after the live pin had welded itself to the pin. Cheap and nasty socket ( but certified to pass the relevant standard) and replaced with another one of a different brand. Used in the kitchen to run a kettle and a microwave, so load is 15A max. Now has a multiplug with thermal cutout, will see how that survives.