How to replace an electric switch

A handyman project for do-it-yourself-ers



Electric switches are subject to lots of wear and tear. They’re usually built tough, but when they break, there’s no need to call an electrician since you can replace it yourself if you’re careful. Here’s a guide showing how to replace a defective bathroom switch. It is public domain meaning feel free to copy text, pictures and diagrams as you wish without attribution. — tom sulcer november 19, 2011

A homeowner’s bathroom switch is broken. Calling an electrician may cost several hundred dollars, but you can fix it yourself using a few key tools and using good common sense. Here’s how.

Here’s the defective switch. The bottom switch (lower right) does not turn on the shower light. The top switch and outlets work.

First, as you probably know, make sure the power is off. Go to the basement and turn off the appropriate switch on the electric panel. If you’re working by yourself, to save trips to and from the main panel, you can plug in a radio or drill or something continually running into the outlet, and flip switches until the radio stops playing or the drill stops spinning. Have a flashlight ready so you can see. If you are still not sure if power to the outlet and switch is off, then you can flip the master switch on the panel; remember that this will shut off the refrigerator, and you may need to reset the time on electric clocks.

Buy a tester such as this one (shown). It is only a few dollars. Make sure to TEST THE TESTER by plugging it into another working outlet to see if it lights up (ie power coming in). In the photo, the little light (lower right) is lit, meaning there’s power AND the tester is working.

Remove the face plate by unscrewing the three screws.

Unscrew the four screws so you can remove both switch and outlet. You can see the two red wire nuts, which attach both the outlet (lower left) and the two switches (upper right) to the house’s wiring.

A tip as you work — lay out what you remove in some kind of order, so you know what’s what when it’s time to put it back together. I lay out the screws, face plate, and such from left to right. Later, I’ll put them back from right to left — an easy way to remember so you don’t forget mess a step.

Next, record exactly the position of the wires. You can write it down, label them, draw a diagram — but it’s important that you remember what was done so you can recreate it exactly. In this instance, the homeowner wanted me to replace both the defective switch AND the outlet so the color would match — white outlets & switch, white cover plates.

Here are some of the tools used. The electric tester (upper left) can be inserted into an outlet — it will chirp if there’s current. But I also use a second tester (middle somewhat left of center), inserting each prong into one of the two holes in an outlet — if the red light lights up, it’s powered. It’s good to double check. Needle nose pliers are helpful for bending stubborn wires.

I do one thing at a time. First, I cut wires to the old outlet. The general rule is: the “hot” incoming power feed, denoted by the black wire, attaches to the GOLD screw, and the “cold” outgoing power feed, denoted by the white wire, attaches to the SILVER screw on the other side. Remember this. Recreate exactly what the previous electrician did so that it will work. The only task we should do is replace the defective parts. I take a good long look at what I am removing so I can recreate it exactly.

Next, use a wire stripper tool (not shown above) to remove the insulation around the black and white wires which emerge from the outlet. Generally, I cut about a half inch of insulation from each wire. The tool trims the insulation away (not cutting the bronze wire) and I rotate it, then pull off the wire’s insulation. I use the needle nose pliers to turn the bronze exposed end into a 3/4 turn — making it bend around clockwise like a peninsula — so it will catch on the appropriate screws. I attach the black wire to the gold terminal, and the white wire to the silver terminal, and tighten with the screwdriver. Here is the new outlet — wired up.

Next, wrap electric tape around the side of the outlet a few times. This is not required by electrical code BUT it is a nice safety precaution since it prevents the exposed screw terminals from possibly coming into contact with another wire inside the box.

Note: there are basically two kinds of outlets. Regular ones and Ground Fault Circuit Interruptor (or “GFCI”) outlets. The regular outlets look like, well, regular outlets. The GFCIs cost a bit more and have two buttons between the outlets. The great thing about GFCI outlets is that if current goes to the wrong place (such as your body) the outlet immediately senses something amiss and SHUTS THE CURRENT OFF IN A NANOSECOND. How wonderful is that! That’s great because if you’re starting to get a shock, the GFCI might just spare your body from getting billions of volts running through it. It can save your life. GFCI outlets are required by code whenever it’s a moist environment such as a kitchen or bathroom. They’re a good idea. If the GFCI trips, you can push the inner button to reset it. It’s important that the GFCI be properly wired and grounded.

Next, here’s the defective switch. It is fed by one incoming “hot” wire (lower left and middle) which attaches to the left side of the switch. There’s a “jumper” underneath the black tape on the left side only so that power goes to both the top and bottom switches. Next, the power flows out to the two different appliances. It should make sense if you know basic electronics. Remember that ONE side of the switch will have outgoing lines, and the other side of the switch has incoming lines. I notice that the wire going to the sink lights is frayed (examine the picture) so I wrap black rubber electrician’s tape around it as a protective measure (not shown in photo). I cut the wires; remove one half inch of wire insulation; use the needle nose pliers to bend the exposed bronze ends clockwise, and attach the new switch. And I wrap black rubbery electrician’s tape around the exposed screws as a safety measure (see next photo).

Note: in a switch, you’re essentially interrupting the
hot wire — putting a temporary pause in its flow — so
in a sense, both the incoming and outgoing wires to a
switch are really “hot” when power flows through them.

Here are the cuts. An alternative is to unscrew the red wire nuts, but in this instance, it’s simpler to merely make cuts as shown.

Since both the new outlet and switch are attached, the task is to gently but firmly squeeze them back into the box. They should fit. Screwing them in can be somewhat of a nuisance and require a few tries to get the alignment exact. I find that the long screws I removed earlier are necessary in this instance since the electrical box is recessed quite far into the wall. It takes some adjustment but the new ones screw in. I have to position them to fit into the white faceplate.

Reattached. Fixed. Sometimes, before I reassemble everything, I turn the power at the main panel ON, then carefully test the switches to see if they’re working; if there’s a problem, there’s less fuss that way. But it works. You’re done!

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