Home Repairs: Single Pole Light Switch

I started writing these home repair articles in the hopes that they would save a few people some money, and allow them to get their feet wet when it comes to that ever present job of home maintenance. Dishing out just shy of $80 to an electrician to change out a simple switch is pointless; more often than not they are just a basic single pole switch, and even when it is something a little more complex (like a 3-way switch) then it's usually just putting the wires back on the same screws you took them off of. Let's start off with the easiest.

A "single pole" switch is simply a switch that has an ON and an OFF position (usually marked as such), has 2 brass colored screws and a green grounding screw, and controls either a single or multiple lights from one location. There are other types, but we'll cover those later. Changing out a single pole switch is done much the same way as a receptacle; if you don't feel comfortable working around electricity then shut off the breaker to the circuit or the main breaker if you aren't sure which one it is.

Besides the ground wire (marked in green or simply bare copper wire) there are two other wires that operate the switch. In most situations both wires of the switch will be black, and you will see at least 2 white wires tucked behind the switch and connected by a wire nut. This means that there is power brought to the switch box on a 14-2G Romex (14-2 indicates a 2 conductor wire with a ground inside of a sheathing. Romex is a name brand, but electricians call everything like it Romex to make identification easier). The power wire connects to the switch while the neutral (usually white but not always) makes up under a wire nut with the switch leg's neutral, and the switch leg's power goes from the switch up to the light.

Too many new words for ya? A switch leg just means a wire that goes from the switch up to the fixture; the wire is only powered when the switch is on. The other side of the switch is constantly "hot", or has live voltage even when the switch is off.

There is another scenario you may run across; what does it mean if there is a white AND a black wire on the switch and nothing else in the box. It was common back in older homes to not bring power into every switch box, but instead to leave it inside a light fixture and bring a single 14-2G Romex down to a switch. In this instance there is a black and a white, and without a voltage tester and the breaker on you won't know which one has voltage - but it doesn't matter. If you only have a black and a white in your switch box then it makes up exactly like 2 black wires.

Remove the switch cover, and then the screws holding your old switch in place. Ensure that it is a single pole switch (only 2 screws on the side plus a ground screw) and then gently pull it out from the box, straightening the wires but not allowing them to rub against the edges of the box if it is metal. Remove the ground screw and fold the ground wire back against the wall. If your wire doesn't have a ground wire inside of it then just continue on as normal.

Loosen both screws on the right hand side and remove the attached wires. If they won't come off the screw then just back the screws all the way out. Make sure your wires are shaped like a "J", and with the switch facing you like it is going back into the wall put the "J" around the screw so that when you tighten down on the screw the "J" closes up and gets tight around the screw instead of being pushed out.

Once both wires are back under their screws you can replace the ground wire, screw the new switch into the box (be careful with the wires - it is fine to fold them a little, but don't let them rub against the edge of a metal box. Also, be sure to check the ground wire and make sure it isn't touching either of the switching screws) and then replace your switch cover.

Congratulations, you've just changed out a single pole switch. 3-way switches are a little more complex, and many electricians have to take a second to think about their operation while diagnosing problems. I'll do another article on those and dimmer switches later. For now, you can turn your panel back on and enjoy your new switch. If you came across something different then don't touch it; call an electrician before disassembling it so they can look at the original setup.

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