Wiring receptacles and switches with stranded wire

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Old 05-19-05, 10:14 AM
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Question Wiring receptacles and switches with stranded wire

I’ve never done this before. Do you make a loop in the wire like you do with a solid core wire for side screw terminations? Or do you put the wire in straight, and then tighten the screw down? I’m going to be using 14ga on my project, but I was practicing with a piece of 12ga wire last night. After stripping the insulation and twisting the wire, it seems like after I get the wire wrapped around the screw and start to tighten the screw the end of the wire wants to fray out a little. Is this normal or is there some “trick of the trade” I should do? I know you have to make the loop “clockwise” so that when you tighten the screw it will pull the loop smaller. Thanks for all your help.
 
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Old 05-19-05, 10:35 AM
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Wink

Dont get why you use strand wire there???? But if you do Id solder them first then bend CW under the screw.

ED
 
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Old 05-19-05, 10:35 AM
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By far the easiest way to use stranded wires is to use devices (receptacles and switches) that are 'back wired'. This sort of termination tends to be found on the higher quality, more expensive devices. Behind every screw there is a hole and a 'pressure plate'. You push the wire into the hole, and tighten the screw. This pulls the pressure plate snug against the wire. No messing with making hooks, and all of the benefit of a screw pressure clamping the wire. This should not be confused with the extremely cheap 'quick wire' where you push the wire into a hole and pray that the spring correctly holds it (these are also called 'back stab' receptacles, with good reason.

Another approach that you can use is the twist the wire 'backwards' prior to making your hook. I use the following technique:
1) Start stripping the wire about 1.5" from the end of the wire. Don't strip the insulation all the way off; expose about 1" of wire.
2) Grab the end of the _wire_ protected under the insulation with pliers. Twist the wire 'backwards'. (You will notice that the wire starts out with a slight _clockwise_ twist; give it a tight _counterclockwise_ twist.) The insulation lets you hold the bundle of wire strands neatly together.
3) After the strands of wire are twisted together tightly, cut off the stripped length to the right length for the hook.
4) Form the hook (clockwise, as normal) and make the connection.

By using the bit of insulation, you can hold the strands together and make a nice tight bundle.

By twisting the bundle of strands counterclockwise, the screw head will tend to pull the strands into the bundle.

Good luck, and practise a few more times before you actually put these connections in walls. Stranded wires take a bit of practise.

-Jon
 
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Old 05-19-05, 10:43 AM
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I forgot to mention that this is outside wiring through PVC conduit, using THWN stranded wire. Thanks guy's for your help.
 
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Old 05-19-05, 11:07 AM
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If the terminal has a clamping plate under the screw such that the screw itself never touches the wire, then you can put the wire in straight under that clamp. I have some Hubbell receptacles with this kind of terminal, and there is no way to really wrap the wire around the screw under the plate, anyway. While I've only used solid AWG 12 on this, I can't see how you could do any differently with stranded. And stranded would probably make a better contact, anyway, because of the meshing of the strands to take the shape of the space under the clamp when pressure is applied.

When I have used stranded wire on an ordinary screw terminal, I generally cut the insulation back a little bit extra (3/16 inch or so). This allows a small amount of the end of the wire to stick out where the extra twisting I add to the wire can help keep the strands from fraying. You will get some deforming of the shape of the wire (bundle of strands) under the screw, but it's making better contact with the screw and the base plate that a solid wire could not do.
 
 

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