Understanding the relationship between Current, Voltage and Power (watts)


I have C.L.A.P
Global moderator
Apr 26, 2010
Albion Park NSW
I got asked a question about current draw that I thought may be worth while sharing with others that may not have the understanding


Is the calculation of 3.2 amps per 5m strip correct? I am running my entire display off one 20 amp breaker. 3.2a @ 12v per strip seems high. Just making sure I am not making a mistake. Mistakes happen to me a lot

The Answer:

Remember ohms law, the current goes up at the voltage goes down so you are thinking of 110v current draw which would be far less

so 350 watts is 350 watts but the current draw changes depending on the voltage

so current = power/voltage

or power = voltage x current

so a strip drawing 3.2 amps at 12vdc will draw about 39 to 40 watts

so that equates to approx 0.4 amps per strip at 110V

and 0.17 amps for 240v

so you can run a fair few strips on one circuit

I hope that helps a few who may not understand the relationship between Volatage, Current and Power