Fun FAQs & Helpful Hints

Watt Is An Amp?

Frequently Asked Question: What is a watt? What is an amp? And why is it important for me to know how many watts or amps my equipments draws?

This is a very good and much asked question.

It's important to know how much electricity your equipment consumes, because all sources of power are finite. Whether you're connected to a battery, a standard AC wall outlet, or the power pole outside your theater, there's a limit to the quantity of power available (albeit a pretty BIG limit, when it comes to the pole's power line  :-)

This answers the last part of the question, because knowing the wattage or amperage (along with the voltage) allows you to determine the type of power source required to operate your equipment.

Now the first parts . . .

An amp is a unit of electrical current. The quantity tells you how much electricity is being drawn through the power cable. A product that draws 10 amps sucks twice as much electricity as a product that draws 5 amps. (That's why it needs thicker wires.)

A watt is a unit of electrical power. The quantity tells you how quickly electricity is being consumed through the power cable. "Consumption" differs from "draw" in that it's relative to voltage, while draw is not. Two products may both draw 5A (5 amps), but if one is 12V and the other 6V, the 12V product will consume twice as much electricity as the 6V product. The 12V product will consume twice as many watts as the 6V product, even though they both draw amps at the same rate.*

P=IV
Power = Current x Voltage
Watts = Amps x Volts

All of these equations say the same thing. You multiply amps by volts to determine watts. Or you divide volts into watts to determine amps. Most equipment will specify the voltage required, and either the current draw (amps) or power consumption (watts); once you know two of the figures, you can use the above equation to calculate the third.

An example is in order. Most electrical products draw 120 VAC. Most electrical circuit breakers are rated at 20A. 20x120=2,400; therefore, you can plug 2,400W of equipment into most AC wall outlets and know that the breaker will not kick.**

Well that's pretty much it for watts and amps.

* Purists may flame me for using the term "consumption" in association with "Watts", but I believe I made it clear that I was talking about the "rate" of consumption, not the actual consumption itself. Power "consumption" is measured in Watt-Seconds, or Joules. (But unless you plan to dispute your electric bill with the utility company, it's really not necessary for you to know this. :)

** An individual standard wall outlet is usually rated at 15A. There are usually a number of these outlets on one 20A breaker. You can draw a total of 2,400W by using two or more of these outlets. You can't actually plug 2,400W into one 15A outlet, as the article may have implied.

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www.theatrefx.com
Theatre Effects, 11707 Chesterdale Rd, Cincinnati, OH 45246
Phone: 1-800-791-7646 or 513-772-7646 Fax: 513-772-3579 *********************************************
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