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USA is typically 110-120VAC, at 60Hz.
A reason for not plugging a surge protector in after a UPS is because it may react unpredictably to the waveform of the UPS when it is on battery. Better ones (like APC) approximate a sine wave, but cheaper and/or older UPS units used to provide more of a square wave, and the usual methods of figuring RMS didn't apply.

hmmm i wonder where those things with 50hz come from.... ohh well they work anyway....

Yea your right I wasn't thinking straight it's 110 and 220 for some reason I was thinking 120 and 240, duh.

While searching, I found this link:
http://www.extremetech.com/article [...] 153,00.asp

I would trust your UPS reading. I installed the APC BN 1050VA yesterday and it confirms that my total draw is 132Watts. I also have a Zalman ZM-MFC2 fan controller that has a Power Meter. The Zalman is showing 108 Watts - if you add my Brother MFC-240C printer, DSL Modem and the Netgear Router That is also plugged into the UPS, the reading of 132 Watts appears to be correct. My system is as follows :

GA-P35C-DSR3 motherboard
Intel E6550 CPU
ATI HD 2600XT
OCZ Hyper 2 G PC6400
Corsair Power Supply HX620W
2 Western Digital 500 SATA drives
2 PATA CDROM/RW drives
Zalman ZM-MFC2 Fan Controller
4 Case Fans (120mm)

An off-line or standby UPS normally powers the load directly from the line, the battery is off-line and not connected to the load. The battery charging circuits trickle-charge the battery to keep it fresh. When power fails, the UPS switches the load to battery power through the inverter very quickly (typically only a few milliseconds). However, there is a measurable period of time when the load is not actually powered. In some very cheap designs, the waveform of the inverter is not phase-synchronized to the waveform of the line, so immediately after the switch to battery power, there can be high inrush currents in capacitive and inductive loads.

Because the load is normally powered from the line, the load bears any power variations, including over- and under-voltage conditions, and variations in frequency or waveform shape. When these parameters exceed some specification, the UPS will switch to battery power.

Some UPS's are labeled as "line-interactive", which is essentially the same thing as an off-line UPS, but does have some ability to regulate the voltage of the load when the load is being powered from line power.

An on-line UPS (sometimes called a "double conversion" UPS) continuously powers the load through the battery. The line power always is rectified and used to charge the battery, and the battery power is always run through an inverter to power the load. When power fails, the only thing lost is the battery charging circuit. The battery and inverter continue operation to power the load with no interruption and no phase-synchronization issues.

Since the UPS's inverter circuit is always powering the load, its regulators are responsible for the output voltage and frequency, so the load is never affected by voltage and frequency variations on the line.

Another difference between consumer grade UPS's and higher end models is the output waveform shape while on battery power. Cheap UPS's use a square-wave output, which is only suitable for powering devices containing DC power supplies, or devices that are agnostic about the waveform shape, like a incandescent light bulb. Better UPS's use a stepped waveform, which approximates utility power. Most line-interactive and enterprise-level UPS's output a pure sine wave. A pure sine wave UPS is the only one that can safely run any type of AC motor (unlikely to be connected to a UPS, but possible).

yo, joe7777, may you recommend a very nice UPS (at least 750w) that outputs a pure sine wave, if not almost-perfect sine wave?

thanks in advance

Try the APC Smart-UPS XL 1000VA.

This is a line-interactive UPS, so it has a small switching transient, but it can protect against over- and under-voltage, and it outputs pure sine waveform.

SomeJoe7777 Does this APC UPS below offer great protection for my computer, or is there one with better faster protection? Also what is the difference between an APC UPS and a Smart APC UPS? Thank you!

http://www.newegg.com/Product/Prod [...] 6842101140

SomeJoe7777, Nice and complete information, you are now the goto guy with regards to UPSs. I think you should take the post you made, start a new thread and have it made a sticky. Maybe flush it out with more details on relative (not specific) price, loading, etc. THG certainly needs more awareness and info about UPSs.

I totally second that! We need someone like you here at THG SomeJoe7777, UPS's are probibly the most overlooked companion for our computers.

Yup, it's been disturbing me for a while.

UPS's and quality PSU's. Neither is flashy and won't make Crysis look better but both could save your system.

Third!

Glad to see you both on board. Comp I thought I lost you.