westom wrote:Even numbers say that voltage drop should not be 15 volts. That your only number is only speculation. Or that you ignored wiring defects. An air conditioner causing a significant voltage drop (dimming lights) means wiring problems. Your dimming (a 4.5 volts drop - not a 15 volt drop) is near zero. The OP does not really say how much dimming he has.
1) Dimming even to 50% is ideal voltage for all electronics. The many concerned about damage to electronics are worrying about a strawman. A UPS for those electronics solves nothing. Money wasted on a threat that does not exist - an unjustified fear.
2) An air conditioner causing 120 volts to drop to 105 volts or 102 volts implies a wiring problem. His air conditioner is causing serious dimming only if a wiring problem exists. A problem easily solved even by a layman. But that unfortunately requires knowledge and inspection. Dimming is caused by poor wiring. Otherwise dimming is near zero - hardly noticed - a threat to nothing.
3) If dimming is serious, the air conditioner (not electronics) is suffering most strain. And another reason why that UPS solves nothing.
UPS solves phatom fears. Dimming is an easily solved wiring problem. Or dimming is near zero - irrelevant. Significant dimming means only an air conditioner is suffering.
If that building has aluminim wires, then dimming may be a major human safety threat. Just another reason why informed layman fix the problem; not cure symptoms with a UPS.
He's...he's unstoppable! Run!