Fun with electricity (or A Question about Wiring)

[Mike]

Hi there, folks. I'm not electrician, but I've changed out a fair number of light switches and outlets in my house. I decided this past weekend to swap out the dimmer switch in my dining room with a regular light switch. I turned off the breaker (which controlled the light switch and the gas stove and microwave which are on the other side of the wall from the light switch I'm working on) and then removed the light switch cover and unscrewed the simmer switch. There are 3 wires coming out of the dimmer switch, 2 blacks and one uncovered (ground) wire. One of the black wires coming out of the dimmer was connected to 2 black wires. The other black wire coming out of the dimmer was connected to a red wire and the ground to the ground. I was puzzled about what to do with that extra black wire in the junction box. I assumed it was the power going to the stove/microwave, so on the new light switch, I connected both black wires to the black screw, then attached the red wire to the gold screw on the new switch and connected the ground to the green screen. All worked fine, though I was confused for a bit about what to do with the extra black wire. Is it a best practice to hook both black wires to the same screw on the light switch?

Oh, one last chapter which was a bit scary. A little later I returned to the newly installed light switch to apply the switch cover. I put it on and noticed the switch was screwed on a bit too far which made it not fit well into the cover. I took the cover back off and unscrewed the screws holding the switch a couple turns. At some point, my screw driver slipped off the screw and went into the junction box and I got a spark and a pop. Scary indeed, but I didn't feel any shock at all. Everything still worked, so I finished putting the cover on. About 20 minutes later, the power to the house went off. I went downstairs and switched off the breaker for the light switch and turned the rest of the house back on. I took apart the switch again and realized that when I caused the pop that the ground wire had broken/snapped and the gold-colored screwed looked like it had been burned (had a little black on it). I re-attached everything and it works fine now. But it was a little frightening.

Mike

[terry]

These sort of posts (the black wire goes here and the red wire goes there ................. ) sort of thing; are real scary. Someone with little/no understanding of electrcity should NOT BE at wiring!

There also seems to be lack of basic understanding that a wire carries electrcity into some sort of basic device, a switch or dimmer or timer etc. and that it comes out the other side ether on, or off, or modifed (dimmed down! And that's how the new or replacement device should be reconnected.

One problem is that once a light/circuit or whatever may 'appear' to work OK!

BUT there may be a potential problem due to the workmanship that may show up later! Glad the writer found that disconnected ground wire eh!

We've had lots of postings here where someone will write, similar to above, that they have rewired the lights in the hallway and now, when they throw the switch, the dining room lights also come on, but very dim! Etc. etc. etc. Bah, blah ............ !

And trying to explain to an amateur electrician how to hook up what are commonly called "Three way light switches" (e.g. one switch a bottom of stairs and other at top; because there are at least three, or more, ways for these to be wired) is painful!

Worrisome!

Interesting too that the writer mentions that the light and the microwave and the gas stove (igniter/light etc.?) are on the same circuit breaker!

One wonders if that is to code in that area and just what is the total wattage on that circuit? A microwave can consume 1200 watts, that's 10 to 12 amps of what is presumably a 15 amp l(#14 AWG?) lighting circuit? Leaving only a couple of amps (ignoring the 80% rule) for all other items on that circuit; when the microwave is operating!

[Pavel314]

My guess would be that the black wire which connects to the red is the hot line to the light. Red is frequently used for the hot line which can be switched off, in my limited experience. The other black wire from the switch connects to two other black wires; again just a guess, but one of those is probably the hot line from the breaker box and the other is a tap off to the stove and microwave, as you had guessed. You'd have to test which lines are hot when the switch is on or off to make sure. It does seem like a strange set-up.

Paul

[RBM]

Nothing strange here, except you shouldn't have more than one wire wrapped around a screw. The two black wires should be pigtailed together with another wire, which goes to the screw. The red wire is the load to the light. The reason you didn't get a shock is because you never got between the hot wire and the ground. Can say the same thing for your screw driver, which obviously did get a shock

[Joe]

Absolutely forbidden. For shame!

[N8N]

No. You should get a short length of black wire, and connect that to the screw on the light switch, then wire nut them together.

Does your new switch have plaster ears? If no, get another switch. If yes, but the wall is messed up around the switch, either patch the wall, or get one of these "device levelers"

nate

[N8N]

Sounds normal to me... black =3D hot, one of them will be hot when disconnected and the other is an unswitched hot to somewhere else. The red will be the switched hot to the light fixture.

nate

[The Daring Dufas]

I be scared O 'letwisity.

TDD

[trader4]

I'd say the power to the WHOLE house going off 20 minutes after he caused the arc with the screwdriver is strange. He also says everything still worked immediately after the arc. Normally, either everything would continue to work or the breaker for the one circuit would trip.

[RBM]

I'd say the power to the WHOLE house going off 20 minutes after he caused the arc with the screwdriver is strange. He also says everything still worked immediately after the arc. Normally, either everything would continue to work or the breaker for the one circuit would trip.

Good point, I missed that part. OP didn't say what he was screwing with 20 minutes after he blew out the switch

[Mike]

.

When the power went out 20 minutes later, I was about to walk out the door with the family. Doing nothing related to the botched light switch operation at all. Bizarre. Anyhow, I'm about to do the "pigtail" thing. That's precisely the answer I was looking for. Thanks to you and everyone for the replies.

Mike

[Metspitzer]

Very good point.

If you do something that causes the main to trip, usually you are not having a good day. :)

[Metspitzer]

I was working at a nursing home once for a company I worked for over

10 years. The electrical closet was a very small room in/at the kitchen. It had a door out into the hall and another one that opened into the kitchen. The kitchen door was right beside the electrical closet.

I was putting in a breaker. The breaker hold down bolt was a hex head, and I didn't have a nut driver that would fit it. I took my needle nosed pliers and was trying to start bolt with them. My hand twitched and the pliers when phase to phase. (Probably not a good idea now that I think back on it)

The sprinkler guy said he could see light coming out of both doors. It didn't trip the main. It kicked the riser main killing power to lights on several floors (Including the closet I was working in). I thought I was blind. It burned the busses badly enough to have to replace the guts. I had to get some more needle nosed pliers too. :)

[The Daring Dufas]

Experience means you burned up thousands of dollars worth of equipment. When someone asks me for a job, I tell them I need someone with experience. Someone who has already burned up thousands of dollars worth of equipment someplace else and is finished with that part of their education. *snicker*

TDD

[terry]

=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D= =3D=3D=3D=3D=3D

See what one means ..........; too many 'probablies' or 'is normallies'!

Someone who at least understands electrical circuitry would sort that out in say ten minutes or less? And would then know which was the live, live to the next light fixture-circuit switched live etc. And if necessary probably mark them in some way.

It really is worrying when someone says "the black goes here" and "the red goes there" .................. Had to tell someone one day they had effectively blown up their brand new programmable thermostat! IIRC it was something about "The red connected to one leg of the 230 volt live and the black to the grounded wall box!!!!!". What a c*ck-up.

[Bill]

Get a book on electrical wiring and read it cover to cover before trying to do any wiring! (Learn first before doing something...)

[DD_BobK]

I agree but those sorts of outcomes tend to drive increased insurance rates, taxes and the desire to pass more laws. :( Better for everyone if they......

get a book, read it & follow the examples. take a class at a CC. hire a tech tutor.

cheers Bob

[aemeijers]

Well, I'm all for not interfering with Darwin, but by the time somebody can afford to have their own wiring to work on, more often than not, they have already started reproducing. And it ain't the kid's fault daddy is a dumbass. So, I don't want the kid fried as collateral damage, or to have to help support the kid for twenty years if daddy ain't around any more.

(Apologies to any female DIYs out there who do their own wiring- I do know you exist, but you are few and far between. And I find most females will Read The Fine Manual.)

I have said for decades, that there should be a 'living in the real world' course required for high school graduation. One unit of the course would be basic household systems, and the care thereof- what is the simple stuff you can do yourself, when you should call a pro, and how to know when the pro is BS'ing you.

-- aem (who knows he isn't really an electrician, and looks in a book or asks an actual expert before he tries anything new) sends...