How to replace light switch from ON/OFF to dimmer?

[tb426]

Hello all members,

New to this forum.

I would like know how to change a traditional ON/OFF switch to a dimmer light switch. The light switch is NOT a 3-way, and is the only switch in the bedroom that can turn the light on/off.

Here are the details with pics:

1) There are three white wires, and are all connected to one single marrettes (Picture 1)

2) There are also 3 black wires, two on top (left corner and right corner), and one at the lower right corner

3) there are two green screw on the inside of the box

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3) Of the three black wires, the top left corner one is twisted like a hook and screwed into the old light switch on the side. It is NOT screwed to the green screw. The other two wires go directly into the switch (Picture 2)

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4) The new dimmer is Lutron brand, and has two black wires and one green wire. From what I read, the green is the ground, but there is no ground wires (or a wire currently screwed to the green screw) in the old switch. (Picture 3)

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Can some experts maybe shed some lights as to how can I wire this myself?

Thanks!

[mjr6550]

You should have instructions with the dimmer switch. The two black wires are connected the same way as with the standard switch. the green wire should be connected to a screw in the metal box where the bare wire is connected.

However, before installing the dimmer switch I suggest that you do some reading on basic electrical wiring. From the questions you are asking it is clear that you do not have any experience in this area. Asking for help is fine, but you should get some additional knowledge so that you understand what you are doing.

[Marc]

The two black wires at the bottom of photo #2 are the 'hot' wires and should be joined together with either of the black wires on the dimmer. The wire at the top in photo #2 is the switch leg which connects to the light fixture. That one connects to the other black wire on the dimmer.

The green wire on the dimmer connects to the two un-insulated wires at the back of the box which should all be connected together before a third un-insulated wire connects them to the box. That makes for 4 uninsulated or green wires coming together in a wire nut.

This assumes that only one light fixture is connected to the switch.

Marc

[Erby]

Look close at the first picture.

There are three - three wire cables coming into the box. Each has a white, black and uninsulated ground wire.

One comes in bottom right

One comes in top right

One comes in top left.

[ghentjr]

First buy a detector of some type that tells you when a wire is hot. There are many different types available. Make sure the power is off. When you try this switch replacement you need to release the two wires that are inserted into the back of the old switch. Use a small flat blade screwdriver inserted into the slot under the wire and it will release the wire. Read up on some basic electric b4 you proceed. You will also need to purchase some wire nuts to connect the new switch wires. Make sure you get the correct size.

[StevenT]

I don't wanna be a party pooper, but to be quite frank; changing from a toggle switch to a dimmer is very basic. If you don't know how to do this basic task, there may be other basics you are not familiar with. Perhaps you should enlist someone to do it, or to teach you how to do it.

Everyone deserves the chance to learn something and I am not against you learning. It's just that this very simple task is something that if done wrong can result in bodily and/or property damage.

Whatever you decide, the first step is to shut off the power supply to the switch.

[kurt]

I'm with Steven on this one. I am also all for folks DIY'ing, it's not hard to do this task, but online instruction on electrical stuff can get really stupid and dangerous. No offense intended to those trying to help, but c'mon folks, don't be hanging yourselves and us out on DIY electrical advice.

Get an electrician.

[tb426]

Thanks for all the inputs. I followed Marc's suggestion and just changed the dimmer and it works perfectly so far!

[David Meiland]

Whoever did the wiring in the photos did a few odd things, or at least things I wouldn't expect to see here.

The ground wires are cut too short, and each is connected individually to the screws in the back of the box. The screw on the left appears to have two wires wrapped part way around it, one in each direction. I would expect to see two of the wires about 6" long, and the third about 12" long. There would be a green wire nut connecting all three grounds together, with the 12" wire coming out the end of the nut and going to the screw (where it would be wrapped all the way around). I don't think I've ever seen a metal box with two ground screws in it.

The third romex in the box is likely a feeder to another switch somewhere (Marc called them both "hot"), but I wouldn't expect to see it connected to the switch. It would be pigtailed with the hot and a 6" wire that went to the switch.

Maybe the guy who did it didn't have any wire nuts. Or, is this typical elsewhere?

[Tom Raymond]

Not here.

The guy that wired the first switch likely only knows slightly more than our OP.

[Jim Port]

There was power in, power out on one side of the switch with the device making the splice instead of a wire nut. The other connection was the switched hot. Nothing at all unusual, but many would consider it less than optimal practice to use the backstab as a splice.

[Jack Davenport]

and to add to Jim Ports post - Nothing illegal about it either

[rkenney]

Looks to me like this guy already has an overfilled box. Stickin' a dimmer into it won't help.

Correct my math if necessary: 14 gauge wire - 6 conductors, 1 ground, 1 clamps, 2 device= 10 x 2.0 = 20 cubic inches.

The box he shows is 2x3 the deepest of which is 18 cubic inches at 3.5 inches deep.

[Jim Port]

The CEC might have different box fill rules.