I've got a situation in my three-story building where the electrical panel is in the basement. My outlet is showing 110 volts, but I believe it should be closer to 120 volts. When my AC unit kicks on, I've noticed the lights dim a bit, which concerns me. The wire run to the panel is about 75 feet long, and I'm starting to wonder if they didn't use a thick enough gauge wire for such a distance, especially since the house was built back in 1910. Is it necessary for me to replace the current wiring with a thicker gauge, or are there other options I can consider? I'm also worried that most of my one-bedroom apartment might be on that same 14-gauge wire.
2 Answers
In my experience, voltage can vary quite a bit depending on how many people in the area are using air conditioning. For instance, at my place, I see as low as 105 volts during peak usage and up to 120 when it’s chill. A 75-foot run with 14-gauge wire typically only results in about a 6-volt drop—even under max load—so you might be okay! It's great that you've got a smaller AC unit, but keep an eye on it and check for any other big appliances that might be straining the circuit.
From what I've seen, if there's not an excessive load, the voltage at your outlet usually matches what you see at the panel. Dimming lights when the AC starts is pretty common, so it might not be as serious as it seems. But if your voltage is consistently low, then it's worth checking the wire gauge and overall load to see if everything is functioning correctly.