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Dimmer switch wiring question (about grounding)

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Dimmer switch wiring question (about grounding)

Postby VEFF on Tue Feb 22, 2005 1:30 am

First of all, I installed a dimmer in my family room several months ago, and there was a bare copper wire (i.e. ground) in the wall box, so i do know what a ground wire usually looks /can look like.

I recently bought a dimmer for the dining room, which I installed today.
I have turned the light off, since I can't figure out if there is or isn't a ground wire inside the electrical box (i.e. that light switch is connected to) in the wall.

Here are the wires in the wall light electrical "box" for the dining room and what, if anything, they WERE connected to with respect to the traditional (non dimmer, just on/off ) light switch:

1 black (had been connected to the previous light switch (non dimmer))
1 black (same as above)
1 red (was not hooked up to anything)
TWO beige connected only to each other inside the box (and were NOT connected to previous switch) - what are these for since they arebn't connected to anything external but are connected together?

I connected each of the dimmer's (not 3-way) two black wires
to one of the black wires in the electrical wall light box.
The light does work fine like this, however the dimmer switch's ground is NOT hooked to anything in the electrical box in the wall (yet), because I couldn't find a loose copper wire and I wasn't sure what the red wire in the electrical wall box was for.
I doubt the TWO beige wires are for grounding, since there would only be one if it were the ground wire.

Could I simply connect (tape with electrical tape) the ground wire to the metal of the electrical wall box to form a ground or is the red possibly for grounding (I tend to doubt it).

As mentioned, I found the previous light switch (non dimmer type) not to be grounded, but I want to ground the dimmer.

What are the possible negative side effects of not grounding?

Thanks for any tips!
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Postby Jim on Tue Feb 22, 2005 5:58 am

You are switching the "hot" black wires. The white commons are tied together. The red is likely another hot if used in a 3-way application. The grounds may be tied together in the back of the box. Since you have metal boxes I'm going to assume the house is an older one. It's always a treat to figure out how an older home was built.

If the grounds are tied together and to the box in the back of it, then the switch will be grounded when you screw it into the metal box.
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Postby VEFF on Tue Feb 22, 2005 10:37 am

Jim wrote:You are switching the "hot" black wires. The white commons are tied together. The red is likely another hot if used in a 3-way application. The grounds may be tied together in the back of the box. Since you have metal boxes I'm going to assume the house is an older one. It's always a treat to figure out how an older home was built.

If the grounds are tied together and to the box in the back of it, then the switch will be grounded when you screw it into the metal box.


Thanks for the reply Jim!

Before I forget: the ceiling candelabra lamp has the two black (one with a stripe) - hot and neutral - and a third wire that is simply a long silver strand.
Is that 3rd wire simply to prevent it from falling to the ground?
What I mean is that I don't know / believe this wire is a ground wire (although to be safe I connected it to the metal of the ceiling electrical box).

The instructions are terrible (just diagrams without text - although they do appear [haven't looked at them in several days since they were basically useless] to show THREE sets of wires being connected as opposed to two).

Yes, it is an older house (1960s).
It hardly looks like one though, other than a few signs, since many parts of it, or its components, have been updated/renovated/remodelled recently by both the previous owners and myself.

I have a question or two:
What do you mean by "[b]switching the hot black wires"?

So the beige (that are tied together inside the box [with a nut] are the commons?
The red is maybe for a fan circuit (or another 3 way type application)?

I followed the wiring instructions for a "single pole" (as opposed to "3-way system") [exact wording not in front of me], since the connections matched that diagram's description as opposed to the alternative diagram (they give two wiring options depending on what kind of system you have).

You mention commons being tied together and, later, say if the grounds are tied together, then...
Unfortunately my box only has ONE set of wires (beige) tied together.
[These are also connected to the back of the box].
I assume that means they are the commons, since I don't think the system would function without commons?



Note: For hallway and bedrooms ceiling lamps, some of which have now been connected for months without any problems, I connected the lamp fixture's ground wire to a metal part inside the box or metal part of the lamp that was in direct contact with the ceiling electrical box, since in all these ceiling electrical boxes there was NO ground wire or I couldn't be sure which wire was the ground wire; in any case, there was no bare copper wire (that would have been clearly for grounding).
Is it possible that there indeed is no ground since these boxes may be old?


By the way, the house's main electrical panel is very new (i.e. was completely replaced a few years ago with a 200W model).

Thanks for any additional tips!
Burners only:
Pioneer DVR-115D
Pioneer DVR-111D
Plextor PX-716A TLA0304
Plextor PX-716A same TLA

LiteOn 52246S 52X CD-RW
LiteOn 52246S (another)
LiteOn 52327S 52X CD-RW
TDK 40X USB 2.0 CD-RW
TEAC CD-W540E 40X CD-RW
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VEFF
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Postby Jim on Tue Feb 22, 2005 9:54 pm

VEFF wrote:Before I forget: the ceiling candelabra lamp has the two black (one with a stripe) - hot and neutral - and a third wire that is simply a long silver strand.
Is that 3rd wire simply to prevent it from falling to the ground?
What I mean is that I don't know / believe this wire is a ground wire (although to be safe I connected it to the metal of the ceiling electrical box).

The instructions are terrible (just diagrams without text - although they do appear [haven't looked at them in several days since they were basically useless] to show THREE sets of wires being connected as opposed to two).

Yes, it is an older house (1960s).
It hardly looks like one though, other than a few signs, since many parts of it, or its components, have been updated/renovated/remodelled recently by both the previous owners and myself.

I have a question or two:
What do you mean by "[b]switching the hot black wires"?

So the beige (that are tied together inside the box [with a nut] are the commons?
The red is maybe for a fan circuit (or another 3 way type application)?

I followed the wiring instructions for a "single pole" (as opposed to "3-way system") [exact wording not in front of me], since the connections matched that diagram's description as opposed to the alternative diagram (they give two wiring options depending on what kind of system you have).

You mention commons being tied together and, later, say if the grounds are tied together, then...
Unfortunately my box only has ONE set of wires (beige) tied together.
[These are also connected to the back of the box].
I assume that means they are the commons, since I don't think the system would function without commons?



Note: For hallway and bedrooms ceiling lamps, some of which have now been connected for months without any problems, I connected the lamp fixture's ground wire to a metal part inside the box or metal part of the lamp that was in direct contact with the ceiling electrical box, since in all these ceiling electrical boxes there was NO ground wire or I couldn't be sure which wire was the ground wire; in any case, there was no bare copper wire (that would have been clearly for grounding).
Is it possible that there indeed is no ground since these boxes may be old?


By the way, the house's main electrical panel is very new (i.e. was completely replaced a few years ago with a 200W model).

Thanks for any additional tips!


I'll try to address the questions as I see them:

1. That silver wire in your candelabra light is a ground.

2. Imagine power as a flow from your breaker box to the light on the black wire and returning on the white/beige commons. You are cutting the flow to the light when you install the switch between the two black wires and have it off. When you turn it on you are in effect tying the two black wires back together.

3. 3-ways only apply if you have two switches operating a light. It's complicated to explain, but you need two wires that can act as "hot" black type wires.

4. It sounds like your house may not have grounds. My brother's house, also built in the 60's, had everything grounded to the commons (white/beige). The whole point is to have a separate path to ground so a malfunctioning appliance doesn't use your body as one. By tying the grounds to common it is like not having a ground at all. I've sometimes seen this done in individual boxes in older homes and even at the electrical box itself. It fools the plug in testers some home inspectors use to check for grounds, but isn't the correct or safe way to go.

5. I believe you have a 200 amp service box. 200w doesn't go far in a home. =)

Jim

5.
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Postby VEFF on Wed Feb 23, 2005 11:29 am

Thanks a lot Jim!

I now need to see if I can fit the two big nuts inside the box behind the dimmer and next to the two existing nuts (total of four large nuts), which is a lot bulkier than a plain vanilla light switch.
The box is pretty deep, but it might be a bit tight.
The dimmer came with small nuts, but only if using a certain combination of wiring width (AWG gauges).
The larger nuts should be used with larger AWG...

I'll use electrical tape around the nuts and part of the wire to prevent any
potential shorts.

Yes, I meant amps; I must have been absent-mindedly thinking in terms of lighting power consumption when I posted hurriedly yesterday morning :)
Burners only:
Pioneer DVR-115D
Pioneer DVR-111D
Plextor PX-716A TLA0304
Plextor PX-716A same TLA

LiteOn 52246S 52X CD-RW
LiteOn 52246S (another)
LiteOn 52327S 52X CD-RW
TDK 40X USB 2.0 CD-RW
TEAC CD-W540E 40X CD-RW
User avatar
VEFF
CD-RW Player
 
Posts: 2025
Joined: Tue Jan 15, 2002 9:36 pm


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