To make a switch loop connect the incoming hot black wire to the white neutral wire that runs to the switch. Switch loops work by stealing a hot thats in an attic or maybe in a light fixture box in the ceiling and sending that hot down to the switch on a white wire then sending the switched side.
Light Switch Wikipedia
3 wire switch loop. At sw1 it is connected to one of the terminals. Both the black and red colors signify a hot or live wire. Of course install a fan rated box support assembly. A white wire signifies a neutral wire. The 2011 nec code requires that the switch loop use wires of the proper color code to signify hot wires. This circuit is wired with a 2 wire cable running from the light to the switch location.
Next wire a new 3 wire up to the ceiling fanlight location from the existing switch box. The neutral from the source is connected directly to the neutral terminal on the light and the source hot is spliced with the white loop wire. The white wire is marked black on both ends to identify it as hot. From a physical wiring standpoint it will be necessary at a minimum to run 143 cable which contains a black red and white wire. Mark the white wire at each end with black tape or black paint to indicate it is hot. When the electrical source originates at a light fixture and is controlled from a remote location a switch loop is used.
Im moving a light switch to a different wall and have found that the cable from the switch to the light has 3 wires but i dont know why. The 2 wire source feeds to an adjacent switch for a differ. Published on jun 4 2018 this shows wiring a light switch when the power comes into the light outlet first. Stack exchange network consists of 177 qa communities including stack overflow the largest most trusted online community for developers to learn share their knowledge and build their careers. Next the incoming white neutral wire is attached to the light fixture as usual and the black wire from the switch is connected to the light fixture. Wiring a switch loop.
And of course connectspliceterminate the egc equipment grounding conductor the bare copper wires to the duplexes and the boxes and the switch as and where required. The old method of a 2 wire drop is explained along with the current code requirements. Tour start here for a quick.
Gallery of 3 Wire Switch Loop
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