power consumption

Discussion in 'Electrics UK' started by njkmr, 14 Sep 2008.

  1. njkmr

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    Hi All,
    just a question about power consumption .Forgive me if I sound numb .

    Anyhow here goes . 10 x 240 v 50 watt bulbs .Or 10 x 12v 50 watt bulbs on transformers .
    Which one is more economical if any .I was thinking the low voltage ones would use less power but the fact they are both 50 watt bulbs is confusing me .
    Can anybody advise as to whether the low voltage ones would use less of my hard earned cash to run.!
    Many Thanks .
    Regards
    Rob.
     
  2. davy_owen_88

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    They are both the same, the only difference is in the amount of current used and therefore the size of cable required...

    50 watts is 50 watts regardless of what voltage it takes...

    50W / 230V = 0.22A
    50W / 12V = 4.17A

    4.17A x 12V = 50W
    0.21A x 230V = 50W

    As you can see 12v lamps draw significantly more current so the 10 lamps will draw nearly 42A between them, so you'll either need a hefty transformer and some huge cable or numerous transformers... Both of which bumps the price up.

    :LOL:
     
  3. njkmr

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    Thanks for the speedy response .
    Regards
    Rob.

    Looks like I will have to keep telling the kids to switch them off then .!!
     
  4. davy_owen_88

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  5. njkmr

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    I should of looked on here before replacing them but never mind .
    I do have them split so I can have 4 corner ones on only or 6 in the middle or all of them together .
    At least I know for future reference .

    Thanks Again .
     
  6. kensplace

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    Would the 12v lamps not end up using more electricity, as they would require a transformer, which will not be 100 percent efficient, so would waste electricity as 'heat' given off from the transformer, plus some wastage in the low voltage cabling (minute probably) as the voltage drop on a 12v cable is likely to be more problematic than on a 240v one.

    The amount is small I would have thought, but the mains one should in theory I guess use a little less than a 12v one...
     
  7. ban-all-sheds

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    Increased voltage drop will just mean less light for your money, not more money spent.

    Basically if you're concerned about running costs don't use incandescent downlights at all - wondering if LV ones use more or less power then ELV ones is a bit like wondering if you should buy a Range Rover or a Land Cruiser because you're worried about fuel consumption....
     
  8. sm1thson

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    yeah but the 12v bulbs are driven at a higher current which is more efficient, but either way they all use a lot so slight differences between them are negligible.
     
  9. njkmr

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    ban -all - sheds ,good reply .lol
    like the comparison to range rover/ land cruiser ![/quote]
     

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