How Much will it Cost to Run my Light?

Loch;942285 said:

Here is an explination to help you figure out your own usage...
I found the formula... this assumes $0.12 per KW hour price... (If you pay a different amount change the formula below)

Explination = Watts used by device (a 400 watts HPS) X hours used over the course of a month = total watt hours
Example = 400 watts x 24 hours/day x 30.5 days/month = 292,800 Total Watt-hours

Explination = now you have to convert Wh (watt hours) to kWh (kilowatt hours) Wh / 1000 = kWh
Example = 292,800 Wh / 1000 Wh = 293 kWh

Explination = now take you kWH and multiply it by the price you pay your electric provider
Eample = 293 kWh x 12¢/kWh = $35.16/mo.; $422/yr.

When you buy electricity they charge you by the kilowatt-hour (kWh). When you use 1000 watts for 1 hour, that's a kilowatt-hour.

Code:

Device                 wattage    Time used  kWh      Cost
HPS                     400 watts   1 hour     .4kWh   $.05
HPS                     400 watts  24 hours   9.6kWh  $1.15
HPS                     400 watts 365 hours 146kWh   $17.52   12/12 for a month
HPS                     400 watts 730 hours 293kWh   $35.16   24x7 for a month
HPS                    1000 watts   1 hour    1kWh     $.12
HPS                    1000 watts  24 hours  24kWh    $2.88
HPS                    1000 watts 365 hours 365kWh   $43.80   12/12 for a month
HPS                    1000 watts 730 hours 730kWh   $87.60   24x7 for a month
small oscillating fan     8 watts   1 hour   0.008kWh  $.00096
small oscillating fan     8 watts  24 hours  0.192kWh  $.02
small oscillating fan     8 watts 730 hours  0.008kWh  $.70
6" Ecoplus inline fan   135 watts   1 hour   0.135kWh  $.0162
6" Ecoplus inline fan   135 watts  24 hours  3.24kWh   $.39
6" Ecoplus inline fan   135 watts 730 hours 98.55kWh $11.83

other examples for various items and hours used below...
medium window-unit AC  1000 watts   1 hour   1kWh      $.12
large window-unit AC   1500 watts   1 hour   1.5kWh    $.18
42" ceiling fan on low   24 watts  10 hours  0.24kWh   $.03
light bulb              100 watts 730 hours 73kWh     $8.76
CFL light bulb           25 watts 730 hours 18kWh     $2.16

Understand that a HPS may use a little more due to ballest, age of ballest and light, small amount for a timer unit... but this is so small as to not worry about.

So in my tent I have a 400 watt HPS going 12/12, an oscilating fan, the 6" inline fan (way over kill for my small 3x3 tent). The timer's usage for my light is so small I am not going to calculate it.

My total cost for the month should be an additional 30.05...

However I also have a 600 watt space heater (fan forced oscillating), but while powered on 24/7 it only uses the full 600 watts when activly heating the small 3x3x6 foot space. Obviously the amount of hours it runs in a month will be varied due to the temp. Even in this super cold month we are having I would say it only runs about 20% of the time at full, the rest of the time it just lights 3 leds and senses the temp, very small usage that I won't calculate...

So if my 600 watt heater only uses 600 watts 20% of the time during a month that would give me 146 hours (20% of 730) to calculate. so 600watts times 146hours = 87600. Divide 87600 by 1000 to get kWh = 87.6. Mutiply 87.6 * $0.12 = $10.52 for the month. Add that to my subtotal from above and it is $10.52+ $30.05 = 40.57.

,
Loch

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