Latest G5 Mac = 12 AMPS AC of Power!

[snekul]

This is just a vent for an annoying experience I've had at work. I deal with both Mac's and PC's at work and we recently put in a new computer lab for the art students--24 brand new top-of-the-line (the exact model escapes me right now) G5's from Apple with the 20" flat panels. Anyway, as soon as we installed all the computers, we started to trip circuit breakers. The room has somewhere between 4 and 6 circuits for the computers (we still need to trace each outlet). Anyway, we took a look at the manuals for the new G5's, and found an unpleasant surprise. At startup and peak load use, our G5's will suck 12 AMPS (AC) of power. Since a standard 3-prong circuit in the US can only provide 20 AMPS of power, each computer will technically now have to have its own circuit to meet electrical code. This is going to cost us a lot of money to fix, since some new heavy duty lines are going to have to be pulled to the lab. Also for those unfamiliar with AMPS, 12 AMPS are 1440 watts AC. It is interesting that I can't find any documentation on the Apple site referencing this power consumption, but it certainly explains that heavy duty power cord that came with each computer! Also, it'll be nice and warm in there this winter.

Edited June 10, 2006 by snekul

[LLXX]

1440 watts power supplies in them? That's a *lot* more than most PCs have...

They should've bought the Intel-based Macs. From what I've heard, they have less power consumption and more performance.

...or just bought high-end PCs.

[snekul]

It is expected that they'd take more power since they are dual processors, but this ammount just seems crazy. Also, we had to buy PowerPC based Macs since Adobe and other graphics software companies have yet to release a version compiled for Intel Macs. Last thing we'd want is to give these art students new computers that appeared to run twice as slow as the old ones. Also since the AC to DC conversion is not very efficient, the actual DC watts for the power supply are going to be less, probably around 1000 to 1200 depending on the efficiency, I'd have to look it up to be sure.

[rendrag]

well, the avg 3 prong circuit is actually only 15 amps. You can tell if it's 20 amps by looking at the neutral prong. If it has a little horizontal line in it, then you have a 20amp circuit.

You will only fail to meet code if the load requires more than 80% of a circuit's rated capacity for more than 3 hours. A circuit won't trip until you go over 100% of its load.

15 amps x 80% = 12amps

20 amps x 80% = 16amps

That said, that's a lot of power required on startup, however that can usually be attributed to 2 things - either a huge nominal power requirement, or woefully inefficient power supply.

Does the manual state what the nominal load is for the computer?

Edit:

V(olts) x A(mps) = VoltAmps

VA x PowerFactor = Watts

PowerFactor is not always equal to 1, especially when dealing with SMPS (switch mode power supplies) which are found in computers.

http://en.wikipedia.org/wiki/Power_Factor_Correction

Edited June 10, 2006 by rendrag

[snekul]

At the university all the outlets (at least in this building) have that horizontal line in the plug to make them 20 amp circuits. The average load appears to be around 3-5 amps, but can rapidily increase if the computer is doing heavy processing.