I have an AC voltage question. I know the "normal" (Under perfect conditions) is 120/240 VAC but how high is too high?
    Right now my computers UPS system says 128V (My Auto-ranging DMM says 127.55) I live in an all electric apartment (Hot Water/Range/Heat/AC) - Which is on almost full blast (As full blast as two* small 5K ones can get)

    I also tried turning on the range (Small 24" unit) and it only dropped by 1/2 a volt

    I can't test the 240V at this time without unplugging the stove or removing the panel cover which is no-no for me as I don't feel comfortable doing that plus it is painted over.

    *= I have two cheap 5000 BTU AC units in a 310 SQFT 1BR apartment both running at the same time on different breakers. The bedroom is separated from the living area by half a wall and no door.

Depend for what purpose:
- Heater appliances are well OK, they are today either equipped by thermostat (oven, main heating, water heater,...), or have a shut down when they finish their task (hit water kettle), so the 7% higher voltage mean only ~14% increase in speed they are able to respond, so quite beneficial to the user. Their design usually have quite a margin to handle the elevated voltage, so no problem at all.
- Computer PSU's and other regulated electronic mean their primary side is less thermally loaded, so it become beneficial for them, mainly for those "universal mains" (so rated 100..240V or so).

- Electronic lamp ballasts: It depend on their concept. If they do contain output regulation and/or contain an active PFC, it would be the same as above, so no performance change and less of internal stress.
But when the output is not regulated, it may feed the lamp with higher power and the output stage could be higher loaded. I would guess the failure rate could theoretically increase a bit, but still, I don't think the difference would be ever noticeable.

- Regulated ballasts (CWA,...): No change, the CWA concept is designed exactly for exactly that purpose...
- Unregulated ballasts (HX, series choke,...): Higher load current, higher losses. If the condition is rather permanent, better look for ballast rated for such voltage.

Generally on all ballasts, your voltage should be within the ballast input voltage tolerance rating (well, with some makers an information hard to get).

And for latest I keep the item (I know) affected the most:
- Incandescent lamps. Their life (assume good quality lamps, so no other effect become dominant over the normal filament evaporation) would drop to about half, but their efficacy rise by about 20% and light output by about 30%, so about one step on the wattage rating types.
Now it depend, what is better for you: For normal household fixtures the cheaper option would be to keep the standard 120V bulbs and select one step lower wattage - the electricity savings would be larger than the extra lamp cost related to more frequent replacements. Remember, with the present lamp vs electricity cost the standard 750 or 1000 hour lifetime is way past the cost effective optimum...
If the lamp replacement become an issue (either shortage in lamp availability, hard to reach fixture or other thing making the lamp replacement complicated), you should go for the 130V rated bulbs
The same is then valid for halogens...