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3 x 40 watt bulbs - how much elec do they use per hour? (120 Watt in total)

  • 13-03-2011 5:33am
    #1
    worded
    Registered Users, Registered Users 2 Posts: 4,639 ✭✭✭


    How much does it cost per hour to leave these lights on? 120 watt in total

    Can anyone calculate the cost?

    Thanks.


Comments

  • #2
    2011
    Moderators, Home & Garden Moderators, Technology & Internet Moderators, Regional East Moderators Posts: 12,641 Mod ✭✭✭✭2011


    0.12 units.

    This wil cost about €0.024

    (unit cost about €0.20)


  • #3
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    Its actualy 16 cent per unit incl vat. 2011 probably rounded it up as its not a huge difference.


    1000 watts in a unit.

    So its 120/1000 x 16 = 1.92 cent an hour or just under €0.02 an hour.

    Or 46 cent for 24 hours continous.

    Or €27 if left on 24 hours a day for the entire billing period.


  • #4
    worded
    Registered Users, Registered Users 2 Posts: 4,639 ✭✭✭worded


    robbie7730 wrote: »
    Its actualy 16 cent per unit incl vat. 2011 probably rounded it up as its not a huge difference.

    1000 watts in a unit.

    So its 120/1000 x 16 = 1.92 cent an hour or just under €0.02 an hour.

    Or 46 cent for 24 hours continous.

    Or €27 if left on 24 hours a day for the entire billing period.

    Thanks for the info.

    We have spot lights 3 per set x 2 in the kitchen. (6 bulbs in total) They are popping bulbs at the rate of at least one every 2 - 3 weeks. Aside from this expense, there is the electricity.


    If we changed to normal energy saving light bulbs how much would we save in electricity?
    We have a kitchen with little light and need them on a lot of the time.

    We will have to change the light fitting as we presently use old spot lights.

    Ive looked at IKEA and see they have a similar set - But use halogen bulbs.
    http://www.ikea.com/ie/en/catalog/products/10158537
    I don’t think there will be any saving if we use these. We may have to opt for another idea.


  • #5
    Bruthal
    Closed Accounts Posts: 13,422 ✭✭✭✭Bruthal


    worded wrote: »
    If we changed to normal energy saving light bulbs how much would we save in electricity?

    Here is how to calculate cost per hour. A kw or kilowatt of electricity costs 16 cent. Divide watts by 1000 to get kw`s, exactly as you would divide meters by 1000 to get kilometers. So........

    Watts / 1000 x 16 cent

    So for a 100 watt bulb

    100 / 1000 x 16 = 1.6 cent an hour.

    20 watt cfl

    20/1000 x 16 = 0.32 cent an hour, or a cent every 3 hours.





    A 9kw shower example. Its in kw already so no need to divide by 1000

    9 x 16 = 144 cent an hour. Seems a lot but its only run for short times.

    If you took the 9kw shower as 9000 watts then its the same as the watts calculations

    9000/1000 x 16 = 144 cent.


  • #6
    worded
    Registered Users, Registered Users 2 Posts: 4,639 ✭✭✭worded


    robbie7730 wrote: »
    Here is how to calculate cost per hour. A kw or kilowatt of electricity costs 16 cent. Divide watts by 1000 to get kw`s, exactly as you would divide meters by 1000 to get kilometers. So........

    Watts / 1000 x 16 cent

    So for a 100 watt bulb

    100 / 1000 x 16 = 1.6 cent an hour.

    20 watt cfl

    20/1000 x 16 = 0.32 cent an hour, or a cent every 3 hours.





    A 9kw shower example. Its in kw already so no need to divide by 1000

    9 x 16 = 144 cent an hour. Seems a lot but its only run for short times.

    If you took the 9kw shower as 9000 watts then its the same as the watts calculations

    9000/1000 x 16 = 144 cent.


    Thanks,

    This site looks good - compares different bulbs
    http://eartheasy.com/live_led_bulbs_comparison.html


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