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How to calculate the electric current drawn by light bulb

It might be useful to find the current drawn by various appliances including bulbs to design and perform house projects.

A Typical Low Consumption Bulb

A Typical Low Consumption Bulb

Almost all bulbs have their power wattage reported on them, for example the bulbs can be 40, 60, 100, etc Watts. This number is the POWER used by the bulb.

60 Watts Bulbs.

60 Watts Bulbs.

The power consumes, P, is related to the operating voltage, V, and the current drawn, I, as the following: Power(P) = Voltage(V) x Current(I)

So to find the current drawn, simply divide the power by the operating voltage. In the United States, most household appliances work at 110 Volts. So the calculation is divide the Wattage by 110.

For example: A 40 Watts bulb draws 0.36 Amps to operate. A 60 Watts bulb draws 0.54 Amps to operate. A 80 Watts bulb draws 0.72 Amps to operate. A 100 Watts bulb draws 0.90 Amps. And so on...

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