In this case one of the black wires in the fan would always be hot unless the breaker is turned. Over time light switches will wear out.
Wiring Diagrams To Add A New Receptacle Outlet Do It
Light switch hot even when turned off. Although dimmer switches do run a little hot even they can become too hot and cause damage. Replacing old light switches is always a good idea. A little investigating showed that when the main breaker was turned off one leg remained hot. The hot contact plate at the center of the light socket and that normally springs back out when removing a light bulb may have lost its stiffness preventing a positive contact with the end of the light bulb and causing it to flicker. Soon the contacts wont meet properly and electricity will flow more freely creating heat. The switch is failing.
This occurs because a dimmer operates by dissipating some of the heat of the full current flow in order to dim the illumination of the light fixture. In order for the light to work with the switch the ceiling light needs to be connected to the switched leg conductor coming off of the switch. Called square d they sent a guy out. When this happens a small spark on the electrical contacts will be emitted whenever you turn the light on and off. Turn the switch on then touch the tester leads to both of the brass terminals on the switch and verify that the tester led goes on. Switch is warm to the touch it is natural for a dimmer switch to generate some heat that can be felt when you operate the switch normally youll feel it when you turn it off.
If the led goes off the switch is good and the wiring is faulty but if the led stays on the switch is bad and needs to be replaced. 3 the reason the light remains on is that the light is permanently connected to another hot wire in the ceiling. So half the circuits in the house were still hot. Light switches that have been hot for a long period of time will overheat the wiring which can burn or damage the insulation. Hot light switches can damage the switch and wiring and it could end up causing an electrical fire. Again this is a fire risk.
Turn the switch off then repeat the test. One possiblility is that the electrician that wired the house used a switch leg to control the fan.
Gallery of Light Switch Hot Even When Turned Off
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