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mrromex
mrromex, Electrical Technician
Category: Electrical
Satisfied Customers: 281
Experience:  over 40 years of all phases related to residential wiring and remodeling
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Why are there three sets of black and white wires coming to

This answer was rated:

Why are there three sets of black and white wires coming to a switch box that only has 2 switches in it. The two switches I have just removed were connected to one another (There was a wire going from one screw on one switch to a screw on the other switch). I believe all of the white wires from each set were capped together. My first thought was to just ignore one pair of wires and hook the switches up to the two sets that looked similar. That didn't work. Now I can't remember exactly how the old switches were hooked up.

-All the whites were together
-There was a short wire going between the two switches (1 screw used per)
-Now I am left with 3 black wires, but only 2 open screws

Can I attach two black wires to one screw? Which two would I connect.

Recommendations, please.

mrromex :

hi this is john and will be happy to help

mrromex :

it sounds like you have a wire going to a light, a wire going to another light and then the feed for both lights

Customer:

Okay... what is the purpose of the feed?

mrromex :

you will need to determine if not already, which wire is the constrant hot....the feed does exactly what it says ...."feed" the switches with power

Customer:

I see.

Customer:

How would I go about determining which is the constrant hot?

mrromex :

do you have a tester with two leads

Customer:

No..

mrromex :

if not we can do this without but have to be careful since you are dealing with live wires

Customer:

yes.

mrromex :

are you game

Customer:

Very much so.

mrromex :

ok....i think you stated that the white wires are already tied together with a wire nut

Customer:

Is there a way to upload a picture of the situation to you?

mrromex :

i dont think i will need one

Customer:

They were. I have untied them. Currently I have the two switches connect to two pairs of black and white wires and the other set is just free.

Customer:

The power is on at the breaker and neither light is working.

mrromex :

ok....lets turn the breaker off and reconnect the white wires back together......when you are finished...make sure they are pushed to the back of the box and then make sure the black wires are seperated before turning the breaker back on

Customer:

Okay. I will return shortly.

mrromex :

then we can find out which is the feed and go from there

Customer:

Is there a trick to getting the three thick copper wires of all the whites twisted together before capping it? It was a bit of an ordeal to get them apart.

mrromex :

the best thing to do is strip the ends back about an inch and start over by twisting two together and then twist the third around them

mrromex :

cut off the excess leaving about a 1/2 inch of twisted wire to screw the wire nut to

mrromex :

the key is to make sure the wires are tight to eliminate problems that may occur later

Customer:

Sorry John. I just realized I lose my internet when the break is off, of course. haha

Customer:

So I have them all tied back and the 3 black are separated.

Customer:

What now?

mrromex :

ok.....you said that there was a short wire connecting the two switches

Customer:

Yes.

Customer:

Black.

Customer:

If that matters.

mrromex :

take one of the other wires being careful not to touch the exposed copper and touch it to the short wire and see if a light comes on

Customer:

So just touch the copper from the short piece to each of the black wires coming from the wall? One at a time?

mrromex :

yes.....be careful as you touch the short one to each one a light should come on

Customer:

Nothing happened. Wouldn't that just extend the wire from the wall?

Customer:

Did you mean to connect the black wires to one another with the short wire?

mrromex :

sorry i misunderstood, when you said short wire i thought you meant a short wire that was in the box

mrromex :

three wires left in the box....correct

Customer:

Oh no. I have a little piece of wire that is separate from everything.

Customer:

Sorry.

Customer:

Yes.

Customer:

All black.

mrromex :

ok........forget that short piece for right now and i will need you to take the first two wires and touch them together and see if you get liught......remember to be careful

mrromex :

light

Customer:

No light. In any combination.

mrromex :

is the breaker on

Customer:

Does that mean I didn't put the white wires together properly?

Customer:

Yes. The breaker is on.

mrromex :

check the connection......of the white wires with the breaker off and make sure they are tight

mrromex :

once you checked...lets try it again

Customer:

Okay. The breaker is in the basement. I'll be a minute.

mrromex :

no problem

Customer:

Okay. Now we have some action!

Customer:

The one on the far right is the feed I presume, as it is the one that is unique to both combinations that illuminate a light.

mrromex :

lights?????

Customer:

Lights!

mrromex :

ok....were you able to figure out the hot wire

Customer:

Yes. It would be the one involved in both combinations that result in light. Correct?

mrromex :

yes....mark it somehow and then turn off breaker so we can do some surgery

Customer:

So I guess I have to screw the hot wire and the short bridge wire into the same screw on either of the lights?

mrromex :

that is really not the best way....you cant put two wires under one screw, it will never be tight enough

Customer:

Okay. I am a sponge John. What do I do? haha

Customer:

Breaker is off.

mrromex :

the best way would be to make a pigtail......you will need two pieces of black wire and a wirenut

mrromex :

you will take the wire that you marked and the two pieces of black wire.....strip the ends and twist together

mrromex :

twist on a wire nut.......this will give you a wire each to attach to one screw each at the switch then the remaining two wires will be attached each to the other screw on the switch....each switch will have one hot and one wire from the light

mrromex :

make sense

Customer:

It does.

Customer:

I think I am good for those switches.

Customer:

I am also working on a dimmer on the otherside of the room.

mrromex :

what they did was make a "jumper with that short piece of wire which is ok but a pigtail is less likely to cause problems

mrromex :

need help with the dimmer

Customer:

I would love some.

Customer:

The dimmer is a Lightolier 600VA inductive dimmer.

Customer:

It has four wires out the back of it.. a red, yellow, black and white. I believe it is a 3-way dimmer, but we don't need it to be 3 way.

Customer:

I have just the white and the black hooked up and the little LED light is illuminated red, but I'm getting nothing by way of light.

mrromex :

there is only one switch that controls the light

mrromex :

ok....if there is only one switch then here is how you should hook up the dimmer........the white gets tied in with the other whites in the back of the box

mrromex :

the black wire is hooked up to the constant hot wire

mrromex :

the wire that is left gets hooked to red and the yellow gets capped off

mrromex :

now in the switch, how many wires are there not counting the whites

Customer:

Sorry. In the switch there is just a black and a white.

Customer:

There is another light but it's switch is hooked up and working.

mrromex :

hate to tell you this but you cant use that dimmer because that one requires a neutral and you dont have one

Customer:

Shoot.

Customer:

Where would the neutral be?

mrromex :

you can put a dimmer there but one that has no lights on it

mrromex :

they sent the feed to the light first instead ogf the switch and brought down a feed and a return wire so when you turn the switch on it sends the feed back up to the light via the black wire.....switches dont need neutrals to operate...that is why they are wire nutted in the box and not hooked up to the switch

mrromex :

so the neutral is in the light

Customer:

drat.

Customer:

okay. thank you.

Customer:

You were a great help.

mrromex :

thats how they did things back then so either you have an older house or an older electrician wired your newer one

Customer:

We're renting in an older house.

mrromex :

where abouts in canada

mrromex :

if you dont mind me asking

Customer:

Toronto

Customer:

Ontario.

Customer:

Where are you?

mrromex :

i have a cabin in western quebec....love it up there

mrromex :

i am in delaware, usa

mrromex :

hope we got you on the right track and good luck with your projects

Customer:

Thanks very much! I guess it's off to the hardware store for me.

Customer:

Take care.

mrromex :

you too

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