Things You'll Need:
- Rating of appliance & or light fixture
- Calculator
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Step 1
To find current (amps) you will need 2 of 3 things: Voltage, Ohms (resistance), or watts.
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Step 2
To find current using Voltage and Ohms, you simply divide your voltage by resistance (current=voltage/resistance) for example, if you have a 120 volt circuit and the resistance of the object is 5 you take 120 and divide it by 5 which equals 24 amps in this circuit.
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Step 3
To find current using Voltage and power, you take your power (watts) and divide it by your voltage (current=power/voltage) for example if you have a light fixture that is rated at 90watts on a 120 volt circuit you will take 90watts and divide by 120 volts which equals .75 amps in this circuit.
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Step 4
To Find current using Power (watts) and Ohms (resistance) you will take the square root of power divided by ohms. For example if you have a light fixture that is rated at 60watts with the resistance of 1 you will divide 60/1=60 and the square root of 60 is 7.74. You will have 7.74 amps flowing in this circuit.
