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Subject - Wiring a new switch from breaker box to light
Jeff Kaden What is the correct way to wire a switch that is between the power source (breaker box) and a light fixture?
Scott Vickrey While answering this, I am assuming this is for a home.
You have a cable coming from the panel and going to the junction box where the light is mounted. Let's call this the home run cable. You have another cable coming from the lights junction box and going to the switch's box. This cable is the switch loop. Both cables have a black, white and bare wires. In the cable from the light to the switch mark the white wire from the switch to anything other than white or green on both ends of the cable (normally accomplished by wraping some black tape around it). In the light's box the black from the panel and the remarked wire from the switch are terminated together. In the switch's box the remarked wire is terminated to one of the screws on the switch that aren't green. The black wire is terminated to the other non green screw on the switch. This wire is called the "switch leg". In the light's box the black wire from the switch is terminated to the black wire from the light fixture. The white from the light fixture is terminated to the white wire from the panel. The bare wires from the light fixture home run cable and the switch loop are connected together and if the box is metallic a piece of bare wire needs to be screwed to the box using a ground screw and added to the connection of the other bare wires in this box. The bare wire at the box needs to be connected to the box if it's metallic and the switch at the green screw. The grounds have to be connected together with a crimp type connector.
Electricman Another method is to feed the switch box with the (home run) splice the white(gounded conductors) together then feed the light box using the black as switch leg and the white as thegrounded conductor. Scott are you saying to use the white with black tape as the switch leg? Because that is a code violation. Sorry if I misunderstand your explanation.
Jeff Kaden Maybe I wasn't clear about what I'm doing. I want to run wiring from the panel box to a wall switch and then wire the wall switch to a ligth fixture. Does it make a difference if the home run is going to the switch and then I wire to the light fixture?
David Hyatt No, I think you are getting confused. Both answers will work. The way you said you were wiring is as follows: run romex from panel to switch, run romex from switch to light. Tap ground wires together in switch box, tap white wires together in box, finally take the two blacks and connect to switch.
Scott Vickrey ElectricMan,
You where correct. I fixed it. This is what happens when you answer questions at 2am.
Electricman 2 am brother what you doin up at 2am?
Scott Vickrey Trying to answer one more question.
iwire OK I have to ask what did I miss here?

If you are using a cable it is certainly allowed for a switch leg to use the white wire as an ungrounded conductor and it is required to be remarked white.

If it is a raceway then no, you may never use a white as a ungrounded conductor.

quote:
200.7(C) Circuits of 50 Volts or More. The use of insulation that is white or gray or that has three continuous white stripes for other than a grounded conductor for circuits of 50 volts or more shall be permitted only as in (1) through (3).

(1)If part of a cable assembly and where the insulation is permanently reidentified to indicate its use as an ungrounded conductor, by painting or other effective means at its termination, and at each location where the conductor is visible and accessible.

(2)Where a cable assembly contains an insulated conductor for single-pole, 3-way or 4-way switch loops and the conductor with white or gray insulation or a marking of three continuous white stripes is used for the supply to the switch but not as a return conductor from the switch to the switched outlet. In these applications, the conductor with white or gray insulation or with three continuous white stripes shall be permanently reidentified to indicate its use by painting or other effective means at its terminations and at each location where the conductor is visible and accessible.

(3)Where a flexible cord, having one conductor identified by a white or gray outer finish or three continuous white stripes or by any other means permitted by 400.22, is used for connecting an appliance or equipment permitted by 400.7. This shall apply to flexible cords connected to outlets whether or not the outlet is supplied by a circuit that has a grounded conductor.


Or did I misunderstand what was trying to be done?
Scott Vickrey Bob since I edited my post a while back you are correct you are missing information. My original post used the remarked white as the return conductor from the switch. As you know this is prohibited by sectionn 200.7(C)(2).