I use three, 300 watt 12 volt Maulibu type transformers to light my
yard and walkway lights around my home.
I was under the impression the reason one would use 12volt instead of
line voltage was the 12v was less costly to run.
How do I determine how much power each of these is drawing (per hr?)
so I calculate my cost per month. I don't think it will matter, but
one of them is only drawing about 160 watts. Each of the others is
near their 300 watt limit.
It will actually cost around 20% more for the 12 volt lights using the same
wattage. This is due to the loss in the transfromer and to a very slight
aditional loss in the 12 volt wires.
Electricity is sold in kilowatt hours. To determin this you take the
wattage of the bulbs (if that is not known, you take the voltage and
multiply it by the current) and multiply it by the number of hours the bulbs
are on. This is watt hours. Then devide by 1000 for the kilowatt hours
(KWH). For the 12 volt system, you have to add about 20% due to the
Watts is watts regardless of voltage. Just add the wattage of all your
bulbs and calculate as you would in the house. The reason fancified outdoor
lighting is lo voltage and not 'line' voltage is because it's safer since
the lines are rarely buried very deep and there's also a much wider variety
of fixtures and bulbs in lo voltage.
On Jan 27, 9:30 am, firstname.lastname@example.org wrote:
They dont use less than comparable wattage 120v lights, probably more
since the transformer wastes energy through heat loss and the 12v
lights may not be as efficient as 120v bulbs. 760 w would cost me
maybe 36$ a month run 12 hrs a day, you have the number 760 watt
figure hours used x your eletic rate, a Kill-a-Watt meter is good.
On Sun, 27 Jan 2008 07:30:36 -0800 (PST), email@example.com
12V lights are cheaper to "install" than standard 120V lights because
of the cheaper materials involved.
300 x 3 = almost a kilowatt. The average cost per kilowatt, last time
I checked, was close to a dime. So you pay about a dime an hour to
run your 3 lights.
How did you come to the conclusion that one of your lights is only
drawing 160W? If you have a 300W lamp in the fixture and are only
getting 160W then something is wrong.
That chart is not the truth after all taxes, no matter what it says.
For Illinois and Indiana its both about .125 Kwh, It was even higher
this year in Chicago area nearing 0.14c Kwh. Check your bill to see if
On Jan 27, 10:30 am, firstname.lastname@example.org wrote:
buy a kill-a-watt brand meter from around $30 and up and plug it in.
to determine your power price, ignore the pennies and look at the
delivered price for usage in your case.
take the total price of the electric bill and divide it by the
kilowatt hours equals cost per kilowatt hour delivered times the
number of kilowatt hours your device uses. the more expensive kill-a-
watt meter has more cost analysis. it is a cross between a clamp-on
ammeter, a recording timer, and a calculator. outdoor lighting is fun,
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