I screwed up: In a light switch, where do I put the black wire, and where the red?

[Digital_is_the_new_Analog]

Just a side note - I replaced most of my outlets and switches last year. The physical layout of the screws was different in some of the new ones. I verified the relationships between the various screws and the switch positions, comparing between the two switches, with a multi meter before attaching the wires to the new one.

[Magiver]

It’s possible to wire a 3 way switch so it works ok with one switch but not the other. You need to see if the other switch works in both directions and reverse the process.

[Snnipe_70E]

@jharvey963

There’s no evidence of handy work around these switches. They seem to be the original ones.

I’m still left with the question of does the black or red wire go on top (or bottom)? Is there any way to determine that by looking at the switch in the garage? For instance, should the (say) red wire be at the same location in the switch in the garage? Or should it be in the top on one switch and on the bottom in the other (assuming the same orientation of the switches)?

Thanks,
J.

There is no way for us to guess which wire needs to be connected with out more information.

You need to figure out which 2 wires are the travel wires and which wire is the source or load wire.

The source or load wire gets connected to the common terminal on the switch. The travelers get connected to the two other terminals on the switch. That means you are also going to need to determine which terminal on the switch is which.

To start you said there are three wires in the box. What color are they? If one is green or bare copper wire then the wrong wire was used to wire up a 3 way switch.

If the wires are Red, black, and blue, or red, black and white the it may be possible. I am assuming you do not have a volt meter, and do you know how to use it if you have one? Testing is easier than trial and effort.

Trial and effort way. REMEMBER TO TURN OFF THE CUIRCUIT BREAKER BEFORE WORKING ON ANY WIRES AND TEST TO BE SURE THAT THERE IS NO POWER AT THE WIRES IN THE BOX. a

Lets call the wires 1, 2, &3, Call the terminals A, B, &C. Call Garage switch G and house switch H.
Connect 1 to A; 2 to B; 3 to C. Put G &H up.
Turn breaker on.
Does light come on. **Yes **
Put H down does light stay on, if so not wired right. If light goes off put G down does light come on no not wired right. If light comes on Put H back up if light goes off it is wired right.

If it is not wired right turn breaker off then
Connect 1 to A; 2 to C; 3 to B. repeat test.

If still not wired right then
Connect 1 to B; 2 to A; 3 to C and keep testing until you have tried every combination.

[Me_Billy]

FYI - In some cases it does matter - so GOOD IDEA to pull out the switch, then take pictures of the wiring on both sides BEFORE DISCONNECTING anything!

Same thing with working on a car (or whatever) - take pictures before taking things apart.

[Magiver]

@Me_Billy

FYI - In some cases it does matter - so GOOD IDEA to pull out the switch, then take pictures of the wiring on both sides BEFORE DISCONNECTING anything!

Same thing with working on a car (or whatever) - take pictures before taking things apart.

In the case of 3 way switches the picture needs to show the writing on the back. The terminals should be labeled.

[jharvey963]

Victory. And it only took me 3 days. When I opened up the junction box in the garage, the switch just fell apart. So by a keen method of deduction, I declared that to be the bad switch.

I wired 2 3-way switches in the circuit. The first time, the house switch turned the light off and on, but when I switched the garage switch, the house switch no longer worked. So I switched the wires on the house switch, and now both the house and garage switch can turn the lights off and on independently.

Thanks for all the help, everyone.
J.

[purplehearingaid]

I personally think it would a safer and cheaper to call an electrician than mess are with wiring in your house .

[percypercy]

This is sort of off the subject, but the guy who built my parents’ house thought it would be really cute if all of the switches were upside down. So what would normally be off is on and vice versa. It drives me crazy and confuses them when they come to a place with normal wiring.

[bob_2]

I am always curious about American electrical wiring, as it is so different from ours. In the UK, light switches are not normally earthed (grounded). There will only be two wires in the back (red and black) and which way they are connected does not matter. A two way switch would have an additional white wire for the link.

From what the OP describes, I think it is high time he had the whole house rewired to modern standards.

[beowulff]

@bob_2

I am always curious about American electrical wiring, as it is so different from ours. In the UK, light switches are not normally earthed (grounded). There will only be two wires in the back (red and black) and which way they are connected does not matter. A two way switch would have an additional white wire for the link.

From what the OP describes, I think it is high time he had the whole house rewired to modern standards.

Generally speaking, ALL wiring points have grounds these days (in the US).
The switches themselves have a safety ground which is connected to the metal frame of the switch, and then to the metal junction box. If this isn’t done in the UK, it sounds very dangerous, especially with 220. Are all switches and boxes non-conductive?

[Tim_T-Bonham.net]

@percypercy

This is sort of off the subject, but the guy who built my parents’ house thought it would be really cute if all of the switches were upside down. So what would normally be off is on and vice versa. It drives me crazy and confuses them when they come to a place with normal wiring.

maybe that guy came here from Europe – many countries there have switches where down is “on”.