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Dissapointed from a LED light bulb...

Discussion in 'General Electronics Chat' started by Externet, Dec 31, 2015.

  1. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    I don't live in Somerset, but I can assure you that's nothing like reality in the UK - it's certainly NOT common for live and neutral to be wrongly connected, or for the earth screw to be lose - and I've been in thousands of homes installing electrical items and never found one like that.

    The sockets are perfectly fine for 13A, and a double socket often feeds two 13A loads at the same time - that's why we have ring mains in the UK.

    I have seen occasional plugs on 3KW heaters burnt and brown, but that's normally because the plug was fitted poorly (not correctly tightening the screws, making a 'high' resistance connection that gets hot) - and the heat from the plug pins can also damage the socket.
     
  2. spec

    spec Well-Known Member Most Helpful Member

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    Yes, common was the wrong word, not unknown would have been better. There is no need to use scare caps and bold, I can read just fine. By the way, I was talking about the mains cable from the user device being reversed, not the house wiring- I have never come across that.

    I do not agree that a twin socket would be OK with both pasing 13A- maybe when properly installed with matching high end plugs but that is seldom the case. Also it is common for the screws in the plug and socket terminals not to be adequately tight and also for the cable entry to be badly formed. There is a design flaw with the terminals on all sockets because of the use of a single small screw, made of soft brass as the only clamp for the cable.

    A ring main is just a convienience. This is made worse, if I remember corectly, because with a ring you need to twist the two 20A solid cores together and then stuff those in the connector. The twisting weakens the core and the little screw also damages the copper, often, and I mean often, the wires are not twisted and one or the other core is not properly secured. It's often said that a ring capacity is twice the value of a single cable, but this is not true for most installations because of the different cable lenths and other risistances in the separate circuits. this means that one ring will pass more current than the other depending on the position of the socket in the ring. By the way, if you really want to see some disaters take a look at emmersion heater wiring.

    A star arrangement is the propper approach. A normal domestic ring is done with 2.5 mm2 20 A cable and a 32A fuse. That means that only two sockets in on the whole ring can be used at full power (26A). (by the way, I do know about diversity)

    I'm not sure what area you work in, perhaps industrial. I should have clarified that I was talking about domestic and then fairly old. But In 1972, we moved into a brand new house and got an electrical certificate. None of the earth terminals were tight: the earth wires were just dangling in the receptacles. I measured and there was no connection to the earth terminal on the wall sockets.

    You do agree that mains plugs and sockets with high currents get hot and brown. The main line manufacturer's sockets and plugs are ok but not the second line stuff.

    An older lady lives next door and I seem to have been appointed Mr fixit it. Around nine months ago she knocked on our door in a panic and said that her mains kept going off- I won’t bore you with what I found! Also, last year I bought an 1878 house- I won't tell you what I found with the electrics either in case it upsets you

    Just to put things in perspective, I know quite a few electricians who are very good, and in the main that is the case. But there are a few others who are not so good and also there is the DIY squad. It is just the same in any profession from road sweepers, through estate agents, through solicitors, through doctors, and so on right up to design engineers.

    Don’t take things personally. :)

    PS: there is a mantra that says: In an organisation 20% of the members do the work and the rest are just members- you are probably one of the 20%
     
    Last edited: Jan 5, 2016
  3. audioguru

    audioguru Well-Known Member Most Helpful Member

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    My electricity is always about 123VAC and the transformers on my street were replaced a few months ago since they were 30 years old. Homes are heated with natural gas not electricity. Old incandescent Christmas tree and Christmas home lights used a lot of electricity but now the current is reduced by LED lights. But in summer we are nearing a brownout condition when many air conditioners are used. So the utility is doing "Peak saver" rewiring of the air conditioners, giving away coupons for LED light bulbs and replacing the thermostats with cell phone controlled ones. Now they can turn off air conditioners to save power. They say only for a couple of hours and we will not notice. Then they can delay or eliminate the need to build another very expensive generating station (probably nuclear).

    I also think that most electricians are honest and work properly. The DIY crowd do the most sloppy and wrong home wiring.
     
  4. dave

    Dave New Member

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  5. spec

    spec Well-Known Member Most Helpful Member

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    Homes in UK are heated mainly with gas too, otherwise, if no gas available, with oil. But many homes now are moving over to electric underfloor heating.

    Xmas tree lights, in general don't use a lot of electricity- this light thing is all platitudes. Also Xmas only arrives once a year and the lights are only on for a couple of weeks at most.

    A serious problem which is caused by incompetence, meddling by the Govenment and the global warming earth hugging crusaders. Every wind turbine for example, not only messes up the country side, but costs a fortune to inatall and maintain. But if that were not bad enough they contibute nothing to the base line capability of the grid because their output cannot be relied on.

    Ridiculous

    What a shambles

    I just said that. There are two types of DIYers: those who know what they are doing and those that don't. Some of the best wiring was done by so called DIYers- botching is another area altogether.
     
    Last edited: Jan 5, 2016
  6. ronv

    ronv Well-Known Member Most Helpful Member

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    I just used Ron S. sim so we would be on the same page. I don't think any of the values make any significant difference to the circuit. I initially thought they were 100 ma diodes, but from looking at them E thought the 50 ma Cree was a better fit. The simulation at 240 volts put the current at 46 ma. so that seemed a good fit.
    I have to go out for a bit, but will run your circuit when I get back.
     
  7. spec

    spec Well-Known Member Most Helpful Member

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    Thanks Ron
    spec
     
  8. Tony Stewart

    Tony Stewart Well-Known Member Most Helpful Member

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    Luminaire designers consider
    1) CCT or color temp ['K'] 4000~5000'K soft , 3500 'K warm >5000'K cool
    2) CRI quality >80% for rendering index 85=good 100=halogen
    3) glare = considered by ratio of incident /reflected brightness ratio.

    It looks like none of these were considered.
    Consider a large shade and use this bulb outside or for the garage
     
    Last edited: Jan 5, 2016
  9. audioguru

    audioguru Well-Known Member Most Helpful Member

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    I consider 2500k as being pink or yellow "warm", 3000k to 3500k as being pure white and 4000k and up as being blue "cool" colors.
     
  10. ronv

    ronv Well-Known Member Most Helpful Member

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    I took a couple of liberties with your voltage doubler.:angelic:
    I hooked up the other side of the bridge and modified the resistor to get the current up to the same as the 240 volt model.
    Works a okay. But alas, still only 7 watts average.:(
     

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  11. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    That wasn't what you said, but even that hasn't applied for decades, as all items come with fitted (and usually moulded) mains plugs.

    Before that, it was fairly common for customers to incorrectly wire plugs on their items, which is why as a retailer we tried to fit plugs for our customers.

    Some do have two screws per terminal, but one is perfectly fine, as 100's of millions of perfect installations show.

    No need to twist them, if anything it makes it worse, and the length of cabling has little effect as it's very low - but you seem to see nothing but appalling poor electricians down your way :D

    You're unlikely to need more than two 3KW at once - hopefully :D

    However, a star arrangement certainly isn't the right way, and hasn't been since the introduction of 13A (fused square pin) plug/sockets many decades ago.

    I work in domestic, your house was obviously a HUGE exception, and used a cowboy electrician - or not an electrician at all?.

    No, only that badly fitted mains plugs on 3KW heaters can go brown.

    I've seen lead wiring :nailbiting:

    The linen insulation doesn't survive very well after all these years, even worse than the rubber mains cabling - but we're talking VERY, VERY old wiring now.
     
  12. zahwi

    zahwi Member

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    It's even worse than that, SPEC has sliding doors with hinges on them. :)
     
  13. spec

    spec Well-Known Member Most Helpful Member

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    I thought you were on my side... turncoat
     
  14. spec

    spec Well-Known Member Most Helpful Member

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    Nigel you are putting slants on everything I say. I seem to spend the majority of my time fighting meaningless battles on ETO. I am tired now.
     
  15. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    It's meaningless when you're (presumably deliberately) making misleading statements about the UK electrical system, which is probably the best in the world.
     
  16. zahwi

    zahwi Member

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    I thought you'll be amused.
     
  17. spec

    spec Well-Known Member Most Helpful Member

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    I thought you would be amused too :)
     
  18. spec

    spec Well-Known Member Most Helpful Member

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    I'm on your side. I think that UK electrical system is marvelous too, so are brit electricians don't be so up tight and don't put words in my mouth.
     
  19. spec

    spec Well-Known Member Most Helpful Member

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    Thanks for the run ron (da do ron ron). The only design aim was for the circuit to work off 120V. The power into the LED string can be increased by increasing the value of the res capacitors to go as bright as you like.
     
  20. Nigel Goodwin

    Nigel Goodwin Super Moderator Most Helpful Member

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    In which case think before you post such deliberately incorrect statements!.
     
  21. spec

    spec Well-Known Member Most Helpful Member

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    Yes sir- so its wire cutters at dawn is it. Anyway, my incorrect statements are more incorrect than yours.
     
    Last edited: Jan 6, 2016

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