Someone in the chat just mentioned something out "balanced neutral" , so I'm going to do a brain dump....

In the US wiring standard we have Leg1 (120v), Neutral (0v) and Leg2(120v). Ideally, the neutral makes sure that your 120v devices get 120v relative to the center point.

What if that center point is missing? Let's disconnect the neutral back to the pole transformer and play along... Imagine you plug a 120v toaster into leg 1 and a 120v coffee maker into leg 2. Since both devices pull about 1200watts, even if the neutral is missing you'll get 240v split evenly between the two devices. if we add another coffee pot, L2 voltage will drop to 80v and the leg with the toaster will rise to 160v. They both still add to 240v but they are "imbalanced" relative to the neutral.

If you have lights that dim or brighten when you run the hair dryer or microwave, look for a loose neutral connection in your load center. The clue is that 120v changes but the 240v stays the same when things are switched on/off.