I've never seen that referenced before and I've read through the NEC codebook (2008). I'm curious - could you point out a code year and page number or such? Just wondering the source since I'm a bit of a skeptic until I can verify it myself. :)

Very true. It's not the best thing out there but it also isn't the most expensive. I'd buy it if I were looking for a low to mid priced MSW inverter and wasn't terribly concerned about the waveform.

That's one internet rumor as to the 'correct' orientation of US style outlets. It is rare to see outlets in commercial or medical settings oriented with the ground up however, despite reasonable claims for this configuration's superiority. National code does not require any specific orientation so every company can choose which way to install them, and I am sure some companies including health care corporations decide to orient them with the ground up.

***** The best argument that I have heard for keeping the ground lug in the lower position is that since most plug wires project outward from the wall, rather than downward, the sheer weight of the cable sometimes causes the plug to sag at an angle. If the ground is at the top, This can pull the ground terminal away from the socket, while leaving the hot and neutral terminals still in contact with the receptacle. You'll have a fully functional appliance that is ungrounded. If this happens with the ground-down configuration, the hot and neutral will lose contact instead, (the safer scenario). I've seen this many times with worn plugs. Btw, I have a Go Power GP1750HD unit, that for reasons that we wont go into, has a crystal with a broken lead. I have serviced a spectrum of electronic devices over 40 years but I must admit that I have never had to replace a stinking crystal before. Do you know of a manufacturer who will sell a 30.72KHZ crystal in quantities of less than 3000? I only need one but I suppose that I could use the rest to pave the driveway or something.

Fred Robinson I'd just get something from Digikey. Doesn't matter which package really, most any crystal will work and can be soldered on with minimal kludgy effort. (granted, if designed properly there are very specific engineering requirements for the crystal to ensure stability, but for a single use application I wouldn't worry) And if it isn't exactly 30.72 I wouldn't worry about it unless you need exactly 60hz for some reason. I've thought about the plug sagging argument but since GND is longer than the others I didn't think it would be an issue so it's interesting that you have actually seen this failure mode before. I have had GND completely break off before though...

***** You may be right about the tolerance...well...tolerance, as nothing about the installation said precision. The crystal was squeezed in between two other components like an afterthought. Everything that I understand about the use of crystals compels a minimal lead length design because those leads are going to impress a spurious capacitance of their own into the circuit, depending upon that length. However, because of its location it was necessary to have the thing stand half an inch off of the pcb to clear the other components. I know, it's only 30KHZ. Anyway, I think the job is going to go south as there were 3 shorted and 5 open circuit mosfets (as well as any other undiagnosed components that quit in solidarity with the mosfets) and the owner is probably not going to like the cost. There are arguments on both sides for the terminal orientation issue so I guess that's why there has never been a standard set. They will probably settle on a convention by the time to upgrade to natural gas powered computers.

Fred Robinson If I had to choose I'd actually prefer the GND to be up. But since nearly every installation is GND down already I say we might as well keep that convention. I don't think it matters much personally.

Most inverters power themselves off of the batteries when disconnected from mains power, so it isn't advisable to leave a UPS unit disconnected from mains for more than a few days. On APC units you can put them into 'storage mode' by holding the 'off' power button for a few seconds until you hear a click. This disconnects the battery from the smarts inside the unit and allows it to be stored for a couple of months. I'm not sure how to put other brands of inverters into that mode.

The ups has 4 relays inside so i followed the tracks and yes the battery is connected to the NO terminal. My question was about the discharge rate while the battery is disconnected from the ups / ups from the plug and offline..

Fábio Santos That would be unusual. The battery is generally connected directly to the switching circuitry and logic since 60A DC style relays are quite expensive.

***** Mind that its a regular computer UPS not a stand alone inverter, i forgot to mention that

I would expect it to be engineered properly, to be of decent quality, and to be a reasonable value. It's a 'safe' choice. That said I haven't put my hands on that particular model.

You think you will review it sometime down the road?

ben d They don't seem to come up as 'broken' too often and the working ones sell for decent money so I'm not likely to review one in the near future. It's difficult to say for certain however.

I haven't seen a quality Exide product to date. They may exist but I haven't seen them. I did have Exides (Group 27 deep cycle) batteries for a while but one failed due to a plate short and the others wanted to leak out of the plastic welds each charge cycle so I got rid of them. These Autocraft batteries are made by Johnson Controls which tends to have better quality.

It's just their way to get power from one side to the other. It may be a bit kludgy but I don't have any complaints otherwise. It's adequate in current carrying capacity and should be reliable.

Sorry, your second