Wiring a switch

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  #1  
Old 11-09-14, 05:22 PM
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Wiring a switch

Hi.
I'm trying to change a simple light switch, but I don't know how to wire it up. Currently, it is wired into a fitting three wires coming in one end (tan (T1) red (R1) and black (B1)) and two in the other end (tan (T2) and black (B2)). T1 is connected to T2. The R1 is connected to the top terminal of the switch and a black wire (B3) is connected to the bottom terminal of the switch, which is connected to B1 and B2. I'm trying to replace it with a switch with two black wires (b1 and b2) and a green (ground) wire (g1), but I'm not sure how to connect it.

My guess (based on some background research) is that the black wires in the wall (B1 and B2) are grounds, tan (T1 and T2) is common, and red (R1) is live. So should I connect b1 to R1, and connect b2 to g1, B1, and B2?

Thanks
 
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  #2  
Old 11-09-14, 05:35 PM
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What is a "fitting"? Do you mean a switch box?
three wires coming in one
Do you mean three cables? A cable is two or more wires in a metallic or non metallic sheath.
three wires coming in one end (tan (T1) red (R1) and black (B1)
Do you mean white red and black? Cables never have tan wires though if old enough aged white can sort of look tan.
My guess (based on some background research) is that the black wires in the wall (B1 and B2) are grounds,
Grounds are green or bare never black.
tan (T1 and T2) is common
Do you mean neutral? Common would only apply to a 3-way switch circuit.
 
  #3  
Old 11-09-14, 06:43 PM
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Do you mean a switch box?
Yeah.

Do you mean three cables?
No, three wires. There are two cables coming into the box, with the one (ostensibly) containing T1, B1 and R1, and the other T2 and B2.

Do you mean white red and black?
I guess. It looks kind of tan. It's also pretty close to white.

Grounds are green or bare never black.
Well, I don't have any green or bare wires, and I'm pretty sure there's a ground.

Do you mean neutral?
I guess so. I'm going off of terms I saw in places like this.

Do you happen to have any wiring suggestions based on the information I gave (which is all that I have)?
 
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Old 11-09-14, 07:21 PM
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Still a bit confused by your current wiring. In the diagram below where do the black and red of the 3-conductor cable go. Is the rest of the diagram correct?

 

Last edited by ray2047; 11-09-14 at 07:39 PM.
  #5  
Old 11-09-14, 07:32 PM
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Looks pretty good. The black wires are connected, and both connect to the top terminal of the switch. The red wire connects to the bottom terminal (I think I mixed that up in my earlier description).
 
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Old 11-09-14, 07:48 PM
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Is this now correct?


Note: position of screws isn't relevant.
 
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Old 11-09-14, 08:01 PM
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Yep, that's it.

position of screws isn't relevant.
You mean upper or lower? I sort of figured as much, but I thought there was a chance it was relevant.
 
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Old 11-09-14, 08:47 PM
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Connect the two black wires to one of the black wires of the new switch and the red wire to the other black wire of the new switch. Coil the green wire up and leave disconnected.

With some switches such as 3-way switches the color of the screw does matter but never position because it can vary with the manufacturer. On a simple SPST switch such as you"re replacing which screw doesn't matter just the wires connected to it.
 
  #9  
Old 11-09-14, 10:53 PM
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The new switch says it won't work unless it's grounded. Should I not just connect the ground to the black wires? I.e., connect b1 to R1, and b2 and g1 to B1 and B2?
 
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Old 11-09-14, 11:06 PM
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You're saying new switch.... do you mean new electronic control... like a dimmer ?
 
  #11  
Old 11-10-14, 12:21 AM
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It's an occupancy-sensitive switch replacing a simple on/off switch.
 
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Old 11-10-14, 08:53 AM
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The new switch says it won't work unless it's grounded. Should I not just connect the ground to the black wires?
NO, Black is hot. Try it without a ground. If it doesn't work buy one that uses a neutral not a ground.
 
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Old 11-10-14, 09:46 AM
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Customer support recommended I try connecting the ground wire to the two white wires (so g1 to T1 and T2, b1 to B1 and B2, and b2 to R1). Can you verify that this is a good idea?
 
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Old 11-10-14, 10:09 AM
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I can verify it will work. I can't verify it is safe. I knew of that hack but couldn't say if it was safe so didn't mention it. I'd go with one that had a neutral unless there is no metal on the switch including the mounting yolk..
 
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Old 11-10-14, 05:13 PM
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In what way is it not safe? What might happen?

I'd go with one that had a neutral unless there is no metal on the switch including the mounting yolk.
There is no exposed metal on the switch, apart from a few small screws that only attach plastic to plastic. Why is that important?
 
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Old 11-10-14, 05:38 PM
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Neutral carries current a ground should not. If you hook a neutral to ground there is a slight chance that under rare conditions if you touched metal on the switch while touching an earth ground you could get a shock. If though the switch is plastic then there is no metal to touch. The screws are isolated so should be okay. You should be safe connecting the ground to neutral.
 
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