Engineering



  • We've got a whiteboard at work. It was fixed to the wall, over a electrical outlet. Someone must've thought that losing a socket would be troublesome, so...

    On top of that, the socket was dead. And a little tilted. It's been fixed, and we've got another whiteboard without an outlet-shaped hole in it now.



  • Whiteboard++



  •  Someone misunderstood the requisition for a e-whiteboard.



  •  Where I work, they mounted a whiteboard on the same wall as the rooms light switches. This lead to them not cutting holes in the whiteboard, but instead mounting it above the switches, meaning the board starts about shoulder height level and extends to the ceiling. Half the whiteboard is basically unusable, except for by the freakishly tall. Not a complete WTF but definitely not optimal.



  • Is it a real whiteboard?  My previous company had white-board paint painted on all the walls of the conference rooms; then trim was installed around the edges to make it look like a whiteboard.  If that is the case, then you just had an outlet inconveniently posititioned where the painted whiteboard was installed.  That's not a WTF.



  • @DrPepper said:

    Is it a real whiteboard?  My previous company had white-board paint painted on all the walls of the conference rooms; then trim was installed around the edges to make it look like a whiteboard.  If that is the case, then you just had an outlet inconveniently posititioned where the painted whiteboard was installed.  That's not a WTF.

    It's not a painted wall but a real whiteboard. They had to change the white sheet when they took the socket away.



  • That makes every presentation a...

    powerpoint presentation

    Yeaaaaaaa!



  •  What country do you work in where they have those weird-shaped electrical outlets? I've never seen one like that; I've never even seen a "universal connector" that could plug into it. Ground in the middle?

     



  •  @AndyCanfield said:

     What country do you work in where they have those weird-shaped electrical outlets? I've never seen one like that; I've never even seen a "universal connector" that could plug into it. Ground in the middle?

     

    http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

     It looks like a swiss socket, or a brazilian one. The swiss socket also accepts ungorunded italina plugs.

     



  • @Morningfrost said:

    http://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

     It looks like a swiss socket, or a brazilian one.

    Or you could look directly under his name where it says Brazil, Sherlock.



  • @AndyCanfield said:

    Ground in the middle?
     

    Most connectors are designed with central ground, if only to provide greater separation between live and neutral, but also to permit the plug being safely reversable.



  • @blakeyrat said:

    Or you could look directly under his name where it says Brazil, Sherlock.

     But it's sweeter this way.



  • @Cassidy said:

    @AndyCanfield said:

    Ground in the middle?
     

    if only to provide greater separation between live and neutral, but also to permit the plug being safely reversable.

     

     

    WTF???

    1. Let me know what kind of requirement dictates live and neutral physically separated by earth in the middle?

    2. Did you see earth was off center horizontally?

     



  • Good ol' Brazilian engineering!

    When I was there earlier this month, we visited my grandfather's country house. There's a little guest house off to the side of the property. One of the exterior walls in the guest house's kitchen doesn't quite meet the support column where it should, so there's a gap big enough to see daylight through.

    I swear, nobody in that country can be bothered to build shit properly. I guess that's what happens when the weather always ranges from nice to mosquitos.



  • @Helix said:

    1. Let me know what kind of requirement dictates live and neutral physically separated by earth in the middle?
     

    I didn't say that it needed to be separated by earth, just that it wouldn't have made sense to me to move live closer to neutral to create space for earth (live-neutral-earth).

    @Helix said:

    2. Did you see earth was off center horizontally?

    For this plug, yep - so it's keyed to being inserted in only one way, much like UK plugs are. However, it still has "earth in the middle".

    Other sockets (some I've seen in Germany, Spain, Egypt) are 180-degree reversible. Most appliances will work with live & neutral switched around, but not if it was live/earth or neutral/earth interchanged.

    I was giving reasons for "earth in the middle" being a common design amongst plugs, rather than this particular plug (which, as you pointed out, being keyed is non-reversible).

     



  • @Cassidy said:

    Other sockets (some I've seen in Germany, Spain, Egypt) are 180-degree reversible. Most appliances will work with live & neutral switched around, but not if it was live/earth or neutral/earth interchanged.

    I've yet to see an appliance with schuko- or euro-plug that doesn't work with the leads reversed (there's no requirement about which side the live and neutral go to in the socket, and there's no markings in either the socket or the plug anyway, so you couldn't connect in a certain way even if you wanted to).



  •  coming from the UK it feels that all other mains plugs are just not safe, and in some cases even designed in a way to allow people to skip out earth on equipment that requires it, or to swap round live and neutral - which is a recipe for electrical shock.



  • @Helix said:

     coming from the UK it feels that all other mains plugs are just not safe, and in some cases even designed in a way to allow people to skip out earth on equipment that requires it, or to swap round live and neutral - which is a recipe for electrical shock.

    It's AC.  From the device's perspective, there is no difference between the two.  As long as the outer casing is isolated from both leads, it doesn't matter.  When the outer casing is used as a ground, it must be connected to a proper ground (neutral isn't sufficient).  US plugs generally fall into two categories - reversible but not ground and grounded but not reversable.  Electrically isolate equipment gets the former and chassis ground devices get the latter.  We also have a variant of the non-grounded plug that isn't reversible, but for passive loads it really doesn't matter.

    I'm not sure why you guys in the UK think your plugs are safe.  At best, the physical packaging partially compensates for the dangerous voltage you use.



  • @Jaime said:

    US plugs generally fall into two categories - reversible but not ground and grounded but not reversable.

    There's also polarized (not reversable and not grounded).



  • @Jaime said:

    I'm not sure why you guys in the UK think your plugs are safe. At best, the physical packaging partially compensates for the dangerous voltage you use.

    And demonstrably there's not a rash of electrical outlet-related deaths in the US or UK. Evidence shows we're safe enough.

    British people will never lower their voltage though, they want their electric tea pot to boil quickly.



  • @boomzilla said:

    @Jaime said:
    US plugs generally fall into two categories - reversible but not ground and grounded but not reversable.
    There's also polarized (not reversable and not grounded).

    I did mention that in my post.@Jaime said:

    We also have a variant of the non-grounded plug that isn't reversible

    The only thing polarization does is allow the device manufacturer to choose a slightly safer configuration.  For example, a standard screw-in type light socket will be wired with a polarized plug so that the neutral goes to the more-likely-to-be-touched screw threads rather than the solder dot in the bottom of the socket.  The edison socket is a 100 year old (and quite bad by today's standards) design and polarization only serves to make it slightly less dangerous.  Also, it doesn't completely serve it's intended purpose.  If the two phases are very out of balance (one carrying a lot more current than the other), or a circuit is heavily loaded, neutral can be quite a few volts from ground.  Another example is something with a switch like a vacuum cleaner.  By using a polarized plug, the switch can be place on the hot lead instead of the neutral lead.  This reduces the risk of shock in the event of something bizarre like splashing a gallon of salt water on it while somehow missing the power switch.  It also helps if some darwin award candidate decides to dismantle the vacuum while it's plugged in.

    For something with a transformer encased in plastic (like most modern power supplies), polarization is pointless.  If there were an actual safety issue, the device would have a grounded plug.  If the safety issue is serious, then code would mandate a ground fault interruptor(e.g. hot tub).



  • @Jaime said:

    @boomzilla said:
    @Jaime said:
    US plugs generally fall into two categories - reversible but not ground and grounded but not reversable.

    There's also polarized (not reversable and not grounded).

    I did mention that in my post.

    Nobody expects the Power Socket Inquisition!



  • @Helix said:

     coming from the UK it feels that all other mains plugs are just not safe, and in some cases even designed in a way to allow people to skip out earth on equipment that requires it, or to swap round live and neutral - which is a recipe for electrical shock.

     

    From what I've seen of UK plugs, you must also feel that all other mains plugs are about half the size they "need" to be.

     



  • There is something about forums isn't there that turns everything into an argument eventually.

    I don't know if its true, or if I'm just so cynical that I read hostility into comments that isn't there but to me it seems similar to when you meet someone head on in the street and you both step the say way and you are both all "Oh I'm sorry." "Isn't this a silly" as you dance around each other, but put someone in a van and the slightest interruption to driving becomes "Get the fk out of my way you stupid f**g ct!"


    Seems to be the same with forums, you disagree with someone or have information to add to a discussion in real life and you will let the minor points slip and present the relevant information politely "Hmm I don't think the polarity issue applies here because the pin is actually slightly off centre." - "Oh yes, so it is."

    Put it on the internet and not only does every point no matter how minor have to be listed but sometimes things have to be made up, just to give someone to a reason to make a comeback at all.


    I can sort of understand how the lack of face to face interaction in the driving/forum environment means that you feel free to say things and express feelings you might not normally do in polite conversation but it gets me the way some comments are so confrontational, its almost like the poster is letting out anger suppressed earlier.



    Anyway, yes the British way of life would be torn apart and riots would ensue if we couldn't boil our tea on good 'ol 240V.


    As for the plugs, I always look at it the other way around, they are twice the size they need to be because of the nannying health and safety culture and it results in plugs more painful than lego! Look at them, it is as if they are design to lay flat on their back in the dark with three prongs pointing directly footward.

    They are a pain the in the arse to pack because you always have to remember to face the pins outwards or risk them stabbing your laptop screen to death (yes even from the outside, I've had that happen to a stupidly flimsy thin-and-light thinkpad before).

    And to make it even more bloody annoying you can just do away with the earth pin altogether because... UK sockets have little flats protecting the phase and neutral connectors which will not open until the earth pin enters the socket (which is why it is slightly longer), otherwise we could have nice flat plugs where earth is not required.

    I've seen some pretty good fold-away solutions to that and the generally large pins problem but you have to go out and look for them because they are of course more expensive that ordinary moulded plugs so no power adapter I have ever bought has had one as standard.

    Ahhh, that is my anger at the plugs of my homeland well and truely vented now, thank you!



  • @EncoreSpod said:


    They are a pain the in the arse to pack because you always have to remember to face the pins outwards or risk them stabbing your laptop screen to death (yes even from the outside, I've had that happen to a stupidly flimsy thin-and-light thinkpad before).


    Euro  and US type plugs have the pins bent or snapped off if not packed properly 

    @EncoreSpod said:



    And to make it even more bloody annoying you can just do away with the earth pin altogether because... UK sockets have little flats protecting the phase and neutral connectors which will not open until the earth pin enters the socket (which is why it is slightly longer), otherwise we could have nice flat plugs where earth is not required.

     

    This is a very silly idea.

    Apart from the shutters most UK sockets have a switch which is only on the live side, meaning that if you have a reversed appliance although it would appear to be switched off at the wall, internally will still be live with respect to earth and therefore be a shock hazard.

    As for the size of plugs do not forget that instead of individual wiring for each socket, we have a ring main.  This means that in a L-E fault in an appliance will require the ring main current (30/32A?) to interrupt the supply. Hence the plug top has a fuse for this kind of fault.  This means that we can select the fuse for the kind of device and lower the chance of fire from cheaply made Chinese switch mode PSU.

     



  • @EncoreSpod said:

    Stuff

    Ah, yes, you seem to be quite right.



  • @EncoreSpod said:

    There is something about forums isn't there that turns everything into an argument eventually.

    No there isn't.



  • @EncoreSpod said:

    Anyway, yes the British way of life would be torn apart and riots would ensue if we couldn't boil our tea on good 'ol 240V.

    FWIW Here in Australia our plugs are closer to the US-style (though with pins at an angle for the polarisation, instead of one pin being wider than the other) and still use the ~240V voltage as the UK.

    @Jaime said:

    For example, a standard screw-in type light socket will be wired with a polarized plug so that the neutral goes to the more-likely-to-be-touched screw threads rather than the solder dot in the bottom of the socket.  The edison socket is a 100 year old (and quite bad by today's standards) design and polarization only serves to make it slightly less dangerous.

    Heh, here we mostly use the "bayonet cap" lightbulb system, though with the Ikea invasion the Edison screw is becoming more common. So the two "solder dots" are completely phase agnostic. (If you are my brother-in-law you are an idiot and try to change the bulb with power applied. Yes there is a good chance for a short circuit, luckily fuses work)

    @Jaime said:

    If the two phases are very out of balance (one carrying a lot more current than the other), or a circuit is heavily loaded, neutral can be quite a few volts from ground

    Around here the neutral is usually connected to ground at the fuse/breaker box, so it shouldn't be that much of a potential difference. The separate earth wire is for safety (safety switch/RCD will cut power if anything flows where it shouldn't). But then most houses only have one phase, with three-phase in the street. Four conductors are strung between poles at 240V with the high tension using three.



  • My apartment doesn't have any grounded sockets.

    Except I think in the kitchen. I don't remember.


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