I installed a bidet toilet seat a few weeks ago. Initially I plugged it into an existing bathroom GFCI protected outlet. That worked just fine, but it required an extension cord on the floor for 6 feet or so, and my wife did not like the way that looked. This weekend I added an outlet near the toilet. Because this is on a different wall, and there is an unfinished attic behind that wall, I used a different circuit - the same one as the bathroom lights. Now when the water heater in the bidet seat comes on, the bathroom lights flicker. It doesn't matter what bulbs I use. Clearly I will have to rewire that outlet to a different circuit. Ideally I would run a new line to the basement where the panel is, but I'm sure I can tap into a different circuit that will avoid the flickering (like the one it was originally plugged into). My question is less about how to solve the problem than about why it is happening. There are other lights on the same circuit, but those do not flicker. All of the bulbs in question are dimmable LED's, but I tried an incandescent bulb in the bathroom fixture, and it also flickered. Why is it that only that fixture has a problem? I can understand how the current fluctuation generated by the bidet seat could cause a problem, but wouldn't the same problem occur on all light fixtures on that circuit? Is there something in the wiring of the fixture itself that is causing only that fixture to be affected?