checking wires?

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  #1  
Old 10-22-04, 08:54 PM
ker
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checking wires?

Okay, on to the outlets. Couple of questions.

1- while switching some of the old outlets with new ones I noticed that the hot wire(where the wire comes into the box and is clamped) has a tiny slash where it seems as though it was cut by a razor blade when the outside insulation was being removed. The neutral looked fine. I tried to pull the wire out some but there was no slack in it. Is there something I can do to patch this up? I can't get tape in there. Again, the wire does not have any nicks, it is just where the black insulation was sliced by a razor blade.

2- also, when changing the ceiling fan, I noticed that box was used as a junction to supply other lights with power. The wires were twiested and there was a wire nut on it. I checked to make sure there was a tight connection and all seemed fine except the wires looked a little roughed up. Probably from when the wires were twisted with needle nose pliars. Again, there is no slack in the wire and I wouldn't have much to play with if I cut the ends off and retwisted. Does this sound normal or okay.

3- Last question (for now that is). One of the junction boxes, I tried to pull on the hot wire to get more slack and "broke" about a 2" piece off. I basically pulled it off. Is this normal. The wire is #12 with the thick insulation that is tough. It has the thin ground in it.

Thanks Again!
 
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  #2  
Old 10-23-04, 05:48 AM
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Location: Central New York State
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When cables are run for new installations there is usually no slack. The only time there is som slack is when a wire is being added after the fact . In this case the wire in the wall usually has some slack because it is not stapled or attached to anything in the wall space.

If you break a wire or damage a wire inside a box, you don't have too many choices. Unless the wire can be used, it must be replaced. This means going back to the junction box before this one and replacing the wire to this junction box. Other options include installing a box between the two and splicing new wire from that box to where the damaged piece of cable is.

Some people use pliers to twist wires together before apllying a wire nut. In theory this is not necessary, but still some people do it. I have even seen electricians who have been in the business for years do this. Copper is easily damaged by pressure. That's why you shouldn't bend cable too sharply. I wouldn't be concerned about small nicks , as long as the wires are securely connected.

As cables age they become less flexible (sounds like us humans). My general rule is that I don;t mess with old cable unless I have to. Doing so, as you found out, is asking for trouble.
 
  #3  
Old 10-23-04, 06:20 AM
Savant
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As for the wires that have nicks and/or cuts in them, it would likely be difficult and costly to rerun them all. In cases like this what I would do would be to use heat shrink tubing and put it in place over the affected sections of wire. If you buy heat shrink tubing that is just slightly bigger than the insulation you ned to cover, when heated it should shrink around the damaged section and provide you with the protection you need. Check your local building supply store for heat shrink tubing, and make sure it is rated for the voltage needed. Whether or not your local code permits this is unknown, but in most cases, so long as it is done properly, the end result would be safe if done correctly. Of course when heating the heat shrink one must be sure not to damage the other wires, but if done carefully and properly, this should address any issues of nicked insulation.

As for the copper wires 'roughed up' when twisted, this is a subject of great debate. Some trains of though suggest that solid wires should be twisted before being capped. Of course when one does this, the 'safe' way to do it is to strip a bit more insulation than needed, grab the ends of the copper wires and twist. Then when you have a good twist, cut off the section that you had your pliers on to make the twist and put on your cap. As such, the copper shouldn't be damaged. Some inspectors in my area require that wires be pre-twisted this way, but they also require that the copper not be too distressed either. However, so long as the copper doesn't look too 'distressed' or about to break off, then I would leave it alone and in it's current twist. Untwisting it would likley only put more stress on the wire.

Regards,

Savant
 
  #4  
Old 10-23-04, 06:23 AM
ker
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"My general rule is that I don;t mess with old cable unless I have to."

Yeah, that was a learning experience. I was trying to figure out what fed what and played with them more thatn I probably should have. Thanks for the reply and help!
 
  #5  
Old 10-23-04, 06:32 AM
ker
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By distressed, do you mean the wires not being too roughed up by the plyers where they almost look clipped or do you mean something else?
 
  #6  
Old 10-24-04, 06:40 AM
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Location: Oregon
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By 'distressed' I believe Savant is describing the wires actually getting stretched out by the twisting process so that small breaks form in the wire.

Try an experiment. Get some 14ga insulated wire. Strip about 2" off of a pair of wires and twist them together with a pair of pliers. Keep twisting them until they break, and observe the changes in the wire. You may note the surface of the wire changing from shiny to sort of diffuse/mat, and you may note that the twisting first gets harder, and then gets easier. If you pretwist the wires, you don't want to twist so far that you are actually weakening the wires. But the only way to figure this out is to practise.

-Jon
 
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