i wanted to ask if bad electricity can travel through the data cables to the well... rear of the hdd dock
Yes, "bad electricity" will travel quite happily through data cables as I mentioned earlier, as it seeks a path down to ground. This is normally very bad news for any devices connected to the data cable, i.e. fried mobo or disk drive.
at this moment i have 2 cables going to that beam
This is good. All items of mains powered equipment should be individually earthed, if the mains cable to the equipment has three wires, including earth.
but shouldnt the UPS take care of that ??? if the voltage is to high, im assuming it gets filtered out .. and if too low, the UPS taps into the battery
Not always. A cheap UPS simply routes mains power straight through to your computer, when AC mains from the local sub-station is present. It doesn't change the voltage. If the local AC mains is 200V, your computer gets 200V. If the local mains is 250V, your computer gets 250V.
Some better quality UPS have an "AVR function". On my ancient 650VA Belkin UPS, when the mains supply went over 245V AC, the AVR function kicked in and the output to the computer dropped by 20V down to 225V. When the mains input hit 253V, the output was 233V. Much safer for the computer.
On most UPS, apart from "always on-line" versions, the only time the battery is used is when the AC mains fails. The instant the mains vanishes, a relay clicks over inside the UPS and the battery powered inverter starts up, providing AC power to the computer for a few minutes, until the battery is exhausted. If the mains returns, the relay changes back, the battery stops supplying the inverter and the computer runs off the local mains.
OR the inverter that claims to be 500 watts isnt 500 watts
I'm not sure if you're talking about the UPS here, but remember, your UPS is rated at only 390W. If you're talking about your Chinese device, they may not have been 100% accurate in describing its spec. Remember VA and W ratings are not the same.
but since you said that my pc could kill me, im reluctant to touch it now
Your PC will only (potentially) try to kill you, if a serious fault develops inside the ATX PSU and the AC Line input (230V AC?) makes contact with the inside of the metal box surrounding the PSU components. 99.999% of the time you will be "safe" touching the ATX PSU case (apart from a buzz?). It's that 0.001% when a bad fault occurs and it's lethal. It might never happen, but do you feel confident it won't ever happen?
however these same cables can handle powering a CRT television
I still have two CRT TVs, but that's beside the point. The cable feeding a TV only needs to provide a few hundred Watts. As such, the 2-core flex is typically only 0.5mm sq (cross sectional area of copper strands). Such wire is rated at around 5A although the TV will only pull a few hundred mA.
Contrast this with the current required to trip a 10A fuse (at least 20A) or a 15A circuit beaker (at least 30A, possibly 50A) during a fault, and you can see that safety earths are best wired in a much thicker gauge of wire. If you want to be sure the fuse/breaker will trip/blow, before the length of horribly thin wire up to the beam glows red hot and vapourises, leaving you vulnerable, then carry on using thin wire for a safety earth.
wouldnt the cable just overheat and melt
Lightning rods on tall buildings or structures are usually connected to ground using thick copper straps, capable of carrying thousands of Amps. I wouldn't use anything less than 10mm sq wire, better still 16mm or 25mm, but I doubt even that would be enough. N.B. I've never installed a lightning rod, so this is merely guess work.
with a beefy rapid charger.. lets say 50 amps
Will your SLA batteries accept a 50A charging current? They might and then again, if they're low capacity 12V 7A, they might not. Only way to tell is to look up the spec of the battery. They might self limit to less than 50A charging current.
get a VERIFIED 1000 watt DC to AC inverter
Fine, if the inverter generates A PURE SINE WAVE, but I doubt you'll find such a beast for less than $300.
a sine wave or modified sine wave inverter, i don't know the difference, but the word SINE is in it..
The word "sine" in the term "modified sine wave" is marketing speak (BS) to lull the unwary into thinking they've purchased a superior product. It looks better in the advertising blurb than square wave, which sounds nasty (and is). Some computer equipment can cope with modified sine, but if you can afford it, a "true sine" or "pure sine" wave UPS or inverter is kindest to your electronics.
At worst, a modified sine might kill your equipment. At best, you won't notice any difference.
The best and most expensive option is an "always online, pure sine wave UPS", with large batteries (big UPS often contain two or four12V 14A batteries for higher outputs and longer run times). You're talking many hundreds of dollars, possibly thousands, but these UPS will protect your computer from most things. Problem is, it's much cheaper to go out and buy a replacement FM2 PC for $60, than spend $1,000+ on a top of the range UPS with extra long run time.