For a 1kw appliance, with 220v it should be 48 ohms, but for 110v it needs to be only 12 ohms. So if you have a bad wire or connector, which has say 5ohms resis

For a 1kw appliance, with 220v it should be 48 ohms, but for 110v it needs to be only 12 ohms. So if you have a bad wire or connector, which has say 5ohms resistance, more of the voltage will drop across it. At 220v it will have 21v across it and be heated by 88W but at 110 it will actually have 32v across it and be heated at 204W. That could easily be the difference between a fire starting and not.