amperage conversion(SOLVED)

[duane.mosley]

 what is the formula to  figure out what my 12v power supplies will be drawing from the 120v circuit? for example, my mega tree will be 1600 nodes split 800 each per power supply. 284 amps equals 23 amps of 12v power. how many amps does that equate to on 120v?


thanks

duane

[Steve Gase]

to do conversions, multiply:
AMPs x VOLTs = WATTs
 
so, 12v LEDs drawing 45 AMPs = 540 WATTs
to get the AMPs for 110v service ...   540 WATTs / 110v = 4.91 AMPs
 

[duane.mosley]

to do conversions, multiply:
AMPs x VOLTs = WATTs
 
so, 12v LEDs drawing 45 AMPs = 540 WATTs
to get the AMPs for 110v service ...   540 WATTs / 110v = 4.91 AMPs
[/qu



duh! thanks steve. brain wasn't working. that conversion I knew, I was letting the whole 12v thing get in the way.

[tbone321]

Don't forget to add about 20% to that number to account for efficiency and overhead.  No power supply is 100% effecient and they always pull more power than they deliver.

[duane.mosley]

Don't forget to add about 20% to that number to account for efficiency and overhead.  No power supply is 100% effecient and they always pull more power than they deliver.
[/quote



I will be using 620 watt power supplies only pulling 284watts per. I bought bigger power supplies just in case I needed more

[tbone321]

It is always a good idea to to buy a larger power supply (within reason) than you need.  If you are calculating current draw and you are getting close to what the circuit can handle, remember to include the overhead value.  A 20A circuit will NOT give you a steady 20A.  Even at 19A, the breaker will trip in a minute or so. 

As another tip, when you use the quote function move the cursor to the end of the [/quote] andthen hit the <Enter> key a few times to close the quote and then start typing after that.  It can be a little difficult to see where the quote stops and you start when your text is also in the quote box.