By Graham Fisher (a.k.a. Nico Escondido)
Many indoor growers, especially the small-time hobbyist or closet enthusiast, begin their grow operation focusing on strains, systems and lights, without considering one of the most important aspects of the growroom: electricity. Understanding the basics of electricity will help you harness this essential facet of cultivation.
Why Power Is Important
Light is the plant’s most essential food, and it’s essential for the indoor grower to know about lumens. The term lumens (light density) refers to the amount of light that hits your grow surface. The more lumens reaching your plants the better, and because of this, many growers focus on how many lights they can fit in their grow space without going above optimal temperature thresholds. The number of lights you can use is dictated by your power supply.
For the grower’s purpose in exploring electricity, we’ll look specifically at lighting (i.e., the number of lights per area and the juice you’ll need to power them). In order to do this, it’s necessary to understand just how much electricity is needed to power each individual light.
How Much Power Do I Need?
Amperes, or amps, are the units used in measuring electric current. The more amps a device draws, the more electricity it is using. Refrigerators, hair dryers and dishwashers all use high amounts of amps compared to regular household appliances. Grow lamps use a lot of amps as well.
A simple way to figure out how much electricity is needed for your lights is to use the standard formula: watts/volts = amps.
Assuming that you’re living in the United States, which supplies its electric current at 120 volts, you then simply divide the number of watts of your light by the voltage to figure out how many amps your light will pull. So, if you’re running a single 1,000-watt high-pressure sodium (HPS) lamp on a standard 120-volt line—and keeping in mind that the ballasts on these lamps cause an intentional voltage drop, so that a ballast wired for a 120-volt current will draw only 110 volts—the equation would look like this: 1,000 watts/110 volts = 9.09 amps.
240 Volts vs. 120 Volts
Voltage is the pressure, or electrical potential, of electricity. The US standard is 120 volts, but Europe and Canada both run on 240 volts.
The biggest difference here as far as growers are concerned is that the more voltage you have, the less current you need to achieve the same power. Simply put, if you double your voltage, you’ll draw half the amperage. This not only saves the grower money when the electricity bill comes, but it also frees up a great deal of extra power to run more lights and equipment.
A common misconception is that a 240-volt current is unavailable in the US. This is false: Many industrial sites and even homes have a 240-volt current feeding them. This is possible as long as an electrician can run a high-gauge main line from the street to the site. However, many indoor growers either don’t have this option or, lacking a legitimate front, opt against it, as this sometimes draws unwanted suspicion to covert grow ops.
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