Arrived onsite and the resident explained that the foyer chandallier when turned on for even an hour or two will cause the smoke detector to go off right down the split foyer stairs on the ceiling. I opened the gang box that controlled the light and checked those connections, as well as the other locations and they’re all perfectly fine. I went down the stairs and found the smoke detector he was referring to was on the ceiling that was dusty, but also subject to pressure and breezes from the front and back door being opened. After looking over the detector it was 6 years old, but also after blowing on it even, it would go off. I’m thinking it has dust in and around it and when any pressure changes happen in the house it’s going off. But then a few moments later i caught the detector flashing red internally at the defective light and let him know that it was defective. I went through and showed him if he were to replace it himself where i would move it to downstairs so it isn’t subject