Replacing Light Switch W/ Switch/Receptacle Combo

I'd like to replace a light switch with a switch/receptacle combo, such as this one - https://www.amazon.com/gp/product/B...M&linkId=cf2fc4fc8e281cbbc4e4b0d74cff5047.

I want to use the single circuit connected to the current switch. I've watched some YouTube videos about the process. It generally looks pretty straightforward. All the videos instruct to use a test light or the like to figure out which wire is hot and which is load. I don't own any such device.

Here's my question - if I connect the load wire and the hot wire backward on the first attempt, will it damage anything? Best I can reason, it would just result in no power to the receptacle. If that happens, I assume I would just shut the breaker off again and switch the hot and load to the correct terminals.

But I surely could be missing something.

Thanks!

Neil

This post was edited by npowell on 02/09/2023 at 07:23 pm.

I think you need to hire an electrician!

For the most part some electronic devices can be damaged by reversing the polarity. It can also make it dangerous for someone else working
on the wiring if the wiring is reversed. It's not difficult to get it right. Looking at the switch in the link the side of the outlet on
the right with the small prong is for the hot wire (black) and the white wire goes on the left. Here is an illustration.

If the switch box only has 2 wires you can not convert it to switch/receptacle because there is no
neutral wire for the receptacle. One of the two existing wires is a hot wire. The other wire becomes a
hot wire when the switch makes contact and becomes the hot wire feed to the light fixture.

I agree with Russ, higher an electrician.

(quoted from post at 21:07:29 02/09/23) For the most part some electronic devices can be damaged by reversing the polarity. It can also make it dangerous for someone else working
on the wiring if the wiring is reversed. It's not difficult to get it right. Looking at the switch in the link the side of the outlet on
the right with the small prong is for the hot wire (black) and the white wire goes on the left. Here is an illustration.
<img src=https://www.yesterdaystractors.com/cvphotos/cvphoto147150.jpg>

Click to expand...

Thanks, Stephen. I agree that it's mostly not difficult to get it right. The hard part for me is knowing which one of the black wires in the box is coming from the breaker. Even that would be pretty easy with a test light. I suppose I could just see which of the two black wires gives a little spark when briefly touched to the white. Or, maybe there's another way to figure out which wire is from the breaker?

Neil

(quoted from post at 21:57:18 02/09/23) If the switch box only has 2 wires you can not convert it to switch/receptacle because there is no
neutral wire for the receptacle. One of the two existing wires is a hot wire. The other wire becomes a
hot wire when the switch makes contact and becomes the hot wire feed to the light fixture.

I agree with Russ, higher an electrician.

Click to expand...

Interesting. Every YouTube video I watched showed a switch box with neutral inside it. So, I assumed (without yet checking) that my box has neutral inside. To the extent that's not the case, I will skip the whole project- it doesn't warrant the $$ for an electrician. Heck, I'm not sure it warrants the $ for a test light;-)

Neil

First thing: Go buy a test light. Any hardware store should have one that looks like a fat pen, and lights up and beeps when it is near any voltage source. If, and a BIG if here, you can ascertain that there is one piece of 3 conductor wire coming into that box, directly from your breaker panel, then you should, SHOULD be able to follow Stephen's schematic to wire it correctly. IF you happen to short between two of the conductors in the box, it will not be a little spark. It will blow a chunk out a screwdriver blade!!!Or literally stop your heart. But at least you will know which breaker just broke. steve

As others said it depends on how your switch is wired.
Some bring the power wire to the switch and then to the light the switch controls.
In this case the neutral will be tied together with a wire nut and the hot wires will be hooked to the switch.

But some boxes are wired where the power wire goes to the light.
In this case they run the switched wire from the light to the switch and back to the light.
There will only be two wires in the switch box and since most just use romex the white wire should have black tape on it
indicating it is a hot wire.
In this case there is no neutral in the switch box so this box will not support a plug.

Since most boxes are wired with the power and neutral to the switch box and that is what you need for the plug to work lets
go from there.
You should have a test light or volt meter to figure out what wire is #1 and what wire is #3 in Stephen's picture.
But if you do not and hook 1 and 3 backwards the plug will not work or may only work when the switch is on.
In this case you just start over and swap number 1 and 3 wires.
You will also need a short piece of wire to go from the wire nut to the silver screw.

While having a test light or volt meter is nice to make sure the power is off to the switch box before starting work; I'm
thinking most on this site are smart enough to know if you turn on the light and then turn off breakers one by one till the
light goes off you can pretty much figure out what breaker controls the switch box.

Anybody who installs or replaces electrical outlets needs a <a href=https://www.homedepot.com/p/Power-Gear-3-Wire-Receptacle-Tester-50542/206212329>polarity tester</a>. They will tell you if an outlet is wired backwards and will test GFCIs. Most houses will have one or two outlets wired wrong. I once found a GFCI outlet that had THREE different wiring errors: backwards polarity, load and line reversed and a bad ground. Note that the polarity tester will find most, but not all, wiring errors.

As others have said, there's a very good chance the light switch you want to add an outlet to doesn't have both hot and cold conductors. The older the house, the more likely this is. Or if the switch happens to be a three-way. Personally, I don't care to have receptacles and switches in the same box; if it was me I'd probably install a second box exactly where I want it. Or get my electrician son to do it for me.

Wiring is polarized for safety, to reduce the likelihood of electrocution. I don't know of any device that will be damaged if its AC polarity is reversed. Given the number of outlets wired with reverse polarity, things would be blowing up every day if this were true.

Neil, As always there's plenty of responses to electrical or legal questions, lots of good folks here
trying to help. Unfortunately no one here can know for sure what wires are located in your switch box so
you cant risk your life or a fire on what's said BY ME INCLUDED !!!

1) It may be ONLY TWO, the Hot in and the Load out to the light... No Ground No Neutral ???

2) It may be THREE wires, Hot in Load out, perhaps a Ground especially if it's a metal box ???

3) It may have THREE wires, Hot in Load out, Neutral passing through???

4) It may have FOUR wires, Hot in Load out, Neutral passing through, Ground ???

If its a metal box it should be grounded but we cant know for sure !!!!!!!!!

Good chance its 1) or 2) It depends on how it was wired and if its a metal (should be grounded) or a
plastic box NO TELLING WHATS THERE NOW !!!!!!!!!!!!!!!

A simple 120 VAC test light or an AC volt meter can identify the Hot provided there's EITHER a Ground
(like green or bare to the metal box) orrrrrrrrrr a Neutral as its 120 VAC from EITHER to the Hot

TO DO WHAT YOU WANT YOU NEED A HOT, NEUTRAL, GROUND. The Hot feeds the receptacles hot terminal plus the
switches hot terminal, the switches Load terminal feeds the light, the Neutral feeds the receptacles
Neutral terminal. Of course the light needs its Neutral SEE STEPHEN NEWELLS DIAGRAM BELOW

ONLY once you know what wires are in your box can you figure out how if possible to do what you want. Put
a 120 VAC test light or volt meter on either of the switches wires and if theres a ground (bare/green) or
grounded metal box and the other lead to it AND ITS EASY TO SEE WHAT WIRE IS HOT and which goes to the
light (Hot when switch is ON)........

As always where fire or life safety are concerned and ESPECIALLY since we dont know whatS there now,
consider consulting a professional electrician or engineer and dont risk a fire or a life

PS a simple 120 VAC test light is cheap and easy at any big box stores CONSIDER BUYING ONE if you do this
yourself YOU NEED IT Are there any White wires (typically Neutral) in the box ??? Any Bare or Green
wires (Grounds) its 120 VAC from EITHER to Hot easy peasey

John T

I agree that you should have no problem doing it yourself. I also agree that you need to get yourself a test light.

Good clear advice. When taking advice from U-Tube electricians it is best to understand the quality of the advice. I have seen some individuals giving advice that didn't understand the basics. Especially in the advice given on hooking up a generator. On the other hand, there are individuals with a wealth of knowledge, like yourself and others on this forum who share that knowledge. I have found a few good explanations of the loose neutral issue several which include a fascinating demonstration. This discussion reminds me of the old farmhouse I grew up in. The upstairs bedrooms only had one light on the wall with a integral pull chain switch and a single receptacle in the bottom of the light fixture.

You can see what wires are in the electrical box and are attached to the switch by removing the cover plate and then removing the switch by loosening two screws that hold the switch to the box. No need to touch any of the wires until you start replacing the switch.

A test light and polarity tester are good investments. Most hardware stores sell basic wiring manuals for a few dollars.

(quoted from post at 22:13:47 02/09/23)
Interesting. Every YouTube video I watched showed a switch box with neutral inside it. So, I assumed (without yet checking) that my box has neutral inside. To the extent that's not the case, I will skip the whole project- it doesn't warrant the $$ for an electrician. Heck, I'm not sure it warrants the $ for a test light;-)

Click to expand...

Every youtube video you watched showed a switch box with a neutral inside it, because there would be no point in showing one without a neutral. Not that providing bad/dangerous information via social media would be unheard of...

Many switch boxes are wired to break the "hot" wire to the light fixture. One run of Romex is strung between the fixture and switch boxes. Power is run into the fixture box, and does an "out and back" to the switch.

Never, ever, ever pass up an opportunity to buy a new tool!

Thanks, for the kind words, I have seen a ton of You Tube How To videos and some (in MY opinion) are trash with BAD advice while others are professional and accurate THAT GOES WITH THE YOU TUBE UNIVERSE. Similar here and elsewhere especially if the advice is offered by non professionals, everybody has an answer for electrical or legal questions, INCLUDING ME LOL the poster is free to take or leave it lol I try my best to offer what I think is good advice but as always NO WARRANTY lol

Nice chatting with you take care best wishes

John T

Thanks so much, guys! As always, you have been very generous sharing a wealth of information. Next step is to see if there are more than two wires in the box. If so, I'll invest in a test light and proceed carefully

Neil

Exactly. What he said!

Buy that tool, read the manual, and proceed safely.
You can't measure anything at the switchbox with the power turned off at the breaker.
You may also need to buy one of the testers that will buzz and light up when it is close to a live power source.

You may also need to buy one of the testers that will buzz and light up when it is close to a live power source.

AMEN DITTO AND X2

A Non Contact Voltage Tester is the best thing since sliced bread. Only ONE probe, NO contact with actual live wires (picks up through insulation), almost ?? idiot proof but Billy Bob and Bubba may be otherwise

John T

Oh, I didn't know you had knot and tube wiring. Like others have said you need a hot stick to determine which is the hot wire and which is
the neutral. They don't cost much and are real handy to have. It takes a little tinkering to get the sensitivity adjusted but it should
chip on the hot wire and get nothing on the other. They are adjustable to where you can test wire with a very low voltage and you get some
voltage on the neutral wire.

If it is a switch leg or 'Loop' it will not have a neutral. Just a hot white wire and black feed to light.