**If I switch a 1,000-watt HPS lamp that uses 110 volts to 220 volts, how would I figure out the amount of electricity I’ve saved? Growing marijuana uses so much electricity…**

To calculate watts, the electric company uses this formula: Amperes x Volts = Watts. You could also use this formula: Amperes = Watts/Volts.

Amperes (or amps) are the current flow, voltage is the pressure, and wattage designates the resulting work production. If you think of it like a garden hose, the diameter of the hose is the amperage, the water pressure is the voltage, and the resultant amount of water is the wattage. Thus, if you turn down the water (decrease pressure) or squeeze the hose (lower amperage), then the amount of water (or work) is altered.

A 1,000-watt marijuana grow lamp uses 1,000 watts (1 kilowatt) while the ballast generally adds to that by about 200 watts. That comes to a total of 1,200 watts. When divided by a standard American voltage (110), it uses around 10.9 amps of electricity. At 220 volts (European voltage), only half the amount of electricity is required to do the same work, so the system uses about 5.68 amps. In any event, it uses 1,200 watts per hour or 1.2 kilowatt-hours, which is the unit most electrical bills feature.

Cannagrow