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Does it matter which wire goes to each screw on a single pole switch?

Does it matter which wire goes to each screw on a single pole switch?

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Old 01-17-17, 10:00 PM
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Does it matter which wire goes to each screw on a single pole switch?

I just saw a tutorial on YT and the guy said it doesn't matter which wire you connect to what terminal in a single pole switch because it's "just a break in the hot wire". Is that right?

That's assuming that power comes in from the light not the switch?

Does power always come in on the white wire if coming from the light?

If so, is that why its marked with black tape?
 
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Old 01-17-17, 10:13 PM
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There are all kinds of single pole switches. The two most common kinds used in residential lighting are the SPST (Single Pole Single Throw) with two screws that is used for switching a light or receptacle from a single location. That type yes the wires are interchangeable. However there is also the SPDT (Single Pole Double Throw) switch more commonly called a three way switch and for that type of single pole switch you must get the wire on the correct terminal.

Note "single pole" is sometimes incorrectly use to refer to a switch that controls a circuit from one location but that is inaccurate since a 3-way switch is also single pole.
 

Last edited by ray2047; 01-18-17 at 06:23 PM.
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Old 01-17-17, 10:39 PM
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That type yes the wires are interchangeable. However there is also the SPDT (Single Pole double Throw) switch more commonly called a three way switch and for that type of switch you must get the wire on the correct terminal
Thanks ray, very helpful! I'm still trying to wrap my head around all this stuff as of starting a couple weeks ago!
 
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Old 01-18-17, 05:20 PM
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Long ago it was quite normal to use a 2 conductor cable to run from a powered light fixture (say formerly a pull chain fixture) down to a switch. Because typical 2 conductor cables have one white and one black wire, the white wire in this portion of the circuit is also hot. Today a white wire used as a hot wire needs to be marked with white tape or stain at both ends.

The actual wire going to the black lead or gold terminal of the light fixture may not be white. So the white wire ends up as the wire bringing the raw hot power to the switch.

The most up to date code requires a neutral in the switch box. So new wiring needs a 3 conductor cable (the third conductor is usually red) going down from the powered light fixture to the switch and the white wire hot problem no longer exists.
 
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Old 01-18-17, 05:30 PM
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Does power always come in on the white wire if coming from the light?
With a switch loop yes, it should. The hot wire should come down from the ceiling on the white wire and go back up on the black wire.
Just think 'white down, black up'.

If you wired it the other way around, hot black down and hot white up, you have a problem.
Both the hot wire and neutral to the ceiling fixture would be white.

Note: Didn't realize AllanJ posted, you can see the need for wire identification.
 
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