In response to a couple previous posts..
I was curious for one hub so I could multiply by number of hubs (
. I don't just have one hub.
50 amp breaker in main panel is 240 v so I have 100 amps at 120. If you double voltage you half the current. This is why power companies actually transmit the power at thousands and thousands of volts. Power = current squared * resistance. By going up to thousands of volts they reduce the actual current to minimal to reduce losses on the lines.
I am planning on using 10 awg wire to match extension cords 10 awg rated for 20 amps. The 80% of capacity rule is for constant current draw. Breakers operate on heat and magnetic. Spikes in the current draw can easily exceed the breaker if they are brief. This occurs any time you were to start an inductive load there are large inrushes of current. Motors and incandescent lights are inductors. Compressors on air conditioners and refrigerators and freezers are the worst culprits. The larger the gauge wire the less resistance it has and you can somewhat longer runs and have more power available at the end because you have less voltage drop because of resistance. I plan in using the extra heavy duty extension cords to somewhat central points and can brand out to the hubs and each branch won't use as much do they can be regular sized extension cords.
I agree the calculation is not accurate because of the small amount of draw on the 3.3 and 5 volt rails but this is negligible in comparison to the 12v rail current draw and there is also an efficiency factor for the power supply itself. Typical power supplies are 80% efficient at converting the 120 into the dc voltages rest is lost to heat.
You can't take the current draw listed on the label unless you are drawing max on all the dc rails. The power supplies I am using hardly draw anything while just sitting there powered on and connected to a hub. The auto adjusting fan sometimes stops and starts as needed but if you put your hand on the power supply you can't even tell its on by heat.
I was primarily curious as to the accruals if anyone had actually measured. I guess I will have to put my meter on it and turn on individual strands and get my actual draw and record it do I will know how many I can put on each.
So far in 9 years I haven't popped any breakers yet because I make sure my loads are balanced as best I can over each leg of the 240 and limit power on each to known limits. Even when I was almost running fully loaded I could run 90 to 100 amps for brief pops and not trip any breakers.
Now gfci outlets tripping that's another story all together and have had years fighting it to find on loose or broken mini bulb on a wireframe and when the rain allowed it to go to ground through the wireframe... But that's what they are supposed to do...