All right, here is the breakdown for all you you who are interested.
For houses with 15A fuses:
Most houses are wired with 15A fuses on normal wall connectors. 15A on a 120V line means it can output 1800W PEAK. Even though a normal household fuse is rated at 15A peak, it is only able to output about 13A on a continuous basis. That means a PSU can safely suck around 1560W from one of these lines. That DOES NOT MEAN that a 1560W PSU loaded at 100% will be ok. You have to take effeciency into account and this is where it gets complicated....
So, if you have a 1600W PSU loaded at 100% and that PSU has an efficiency of 80% it is actually drawing 1920W (1600W + 20% power waste). So there goes your breaker.
Basically, when plugged into an outlet with a 15A fuse the MAXIMUM PSU size you can have (when loaded at 100%) is about a 1300W PSU which must be rated at 80% efficiency OR MORE. (1300W + 20% waste = 1560W).
For houses with 20A fuses:
Some houses (and my condo) are wired with 20A fuses. It is still running at 120V so these lines can output a PEAK of 2400W and about 2100W continuously.
Now, if we do the same thing as we did above we come up with some interesting numbers. On a 20A outlet we can have an approximate maximum of a 1700W PSU (at 100% load) with 80% or more efficiency. Anything above that and the breaker will probably blow.
Now you can also see how important efficiency is if we ever need these crazy-big PSUs.
 |