Why would 80PLUS not certify any 115V power supply as “Titanium”? [closed]

Question

80PLUS.org lists a set of efficiency requirements for correct supplies for both 220V and 115V main power voltages. However, for the 220V ratings, all manufacturers are held to a slightly higher standard of efficiency, and the highest rating is not possible for typical US household (115V) current.

Is there something inherently more efficient about 220V power which makes it inherently more efficient and therefore deserving of more stringent standards? (Of course, the impedance load induced by wiring might be higher for 115V voltages; though I don't think that ends up being too large at typical power supply amperage and line impedance. I could be wrong there though...)

Answer 1

I^2*R losses (in the wiring) scale with the square of the voltage. Half the voltage means four times the I^2*R losses. Typical home wiring resistance might be .5 ohms.

So, let's take a 450W power supply that's 90% efficient. It draws 500W. At 115V, that's 4.3478A while at 220V, that's 2.2727A. So the I^2*R loss is 2.58W at 220V but 9.45W at 110V. The difference, 7W, represents an extra 1.5% of effective power supply efficiency.

Since Titanium is targeting 96% efficiency, you can't just ignore the 1.5% loss. That's 1/3 extra loss.