I have 12 led strips that each came with a 3 amp/12vDC power supply. I want to connect all 12 strips to one DC power supply. How do I calculate the size power supply I need? Do I increase the wattage or the amperage?
Do I increase the wattage or the amperage? Both! Watts are a product of volts multiplied by the current. P=I X E where P is watts, I is current and E is voltage. You will need to connect your LED strips in parallel, so 12 strips at 3 amps each will be 36 amps. And 36 amps times 12 volts will be 432 watts.