No, a light switch is a device it does conduct electricity when closed but it is not a conductor. Wires are conductors.
A switch simply opens a circuit, stopping the flow of electricity. For example: a simple circuit would be two wires from a battery, one of which goes to a switch, and the other goes to a light bulb. A third wire goes from the other side of the switch to the other conductor of the light bulb. With the switch closed the circuit is complete and the light goes on. Open the switch and the circuit is broken and the light goes off.
A 'polarity test', as it applies to a switch, is performed to confirm that the switch is located in the line conductor and not in the neutral conductor.
You'd need to branch the circuit before the switch. This can be immediately before the switch, in the box that holds the switch, but you can't get constant power from a switched circuit after its been switched.
Your question is rather vague but, for a.c. systems, a switch must always be placed in the line conductor, neverthe neutral conductor.
It is a conductor, but the filament is a resistor : as current flows through the filament, some of the energy is released as heat and light.
The "contact" ... that is, the point where one side of the power circuit is connected ... must be a conductor. When the switch is 'open', then one contact is physically separated from the other one, and no current flows between them. But the contacts themselves are still conductors.
A switch is a device that can either be a conductor or an insulator. When the switch is off, it becomes an insulator and resists the flow of electricity.
If there are three current carrying conductors terminated on the switch you want to replace, then you can not use the new switch at this location. What it sounds like is the existing switch is part of a three way light switching circuit. Check online for images of "wiring of three way switching systems" and you will see what I mean.A regular light switch will only have two termination points on the switch. This type of switch could be a direct substitute for the interval timer switch, as both have only two terminal points.The only way that you could use the new switch in this circuit is to cut in a new junction box for the new switch adjacent to one of the existing light switch boxes. One end of the circuit would use the new switch for opening the incoming "hot" conductor or at the other end of the circuit, the new switch would open the conductor that goes to the light (load). If this method is used the existing switches will not be used for controlling the light and must be in a position so that the light will be always in the on position.If the three way switching is not needed then the existing switches can be removed and the wiring in the boxes can be rewired to accommodate the new switch and the other box would be blanked off.
No, the neutral conductor will not be in that box. The white wire in the end of run will be the return "hot" leg back to the light fixture. When wired this white conductor should have had a black tape marker put on it to signify that it was not a neutral conductor. That same conductor should also have had a black marker placed on the end in the fixture's junction box.
where is brake light switch
It is the brakes light switch
A switch simply opens a circuit, stopping the flow of electricity. For example: a simple circuit would be two wires from a battery, one of which goes to a switch, and the other goes to a light bulb. A third wire goes from the other side of the switch to the other conductor of the light bulb. With the switch closed the circuit is complete and the light goes on. Open the switch and the circuit is broken and the light goes off.