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I'm going to ask a question here that may sound dumb but, hey, you may never learn anything new if you are afraid to ask. - While working on a lot of older homes I sometimes notice that the insulation on some of the NM cables can be very, very difficult to strip. It's as if the insulation is just glued to the copper. I have always thought this was probably due to the effects of overloading and heating over the years, degrading the insulation. (With an FPE panel in place, the likelihood of uncontrolled overloading is probably all the more likely.) - Could there be another reason for this?
On occasion I find some discoloration. Okay, then I know the wires have been getting too hot, but sometimes I do not see any discoloration or, at least, it is less obvious. - Anyway, I am really just checking here to see if I am missing anything. Thanks in advance... :jester:
 

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You hit it on the head. And lots of times the problem stripping the insulation is worse in attic junction boxes where the ambient heat is high and adds to the heat load on the wire. Another example is older fluorescent fixtures when the ballasts go bad, stripping insulation sometimes from the wires to the tombstones is harder than well, you know what from the ballast getting way too hot.
 

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I'm going to ask a question here that may sound dumb but, hey, you may never learn anything new if you are afraid to ask. - While working on a lot of older homes I sometimes notice that the insulation on some of the NM cables can be very, very difficult to strip. It's as if the insulation is just glued to the copper. I have always thought this was probably due to the effects of overloading and heating over the years, degrading the insulation. (With an FPE panel in place, the likelihood of uncontrolled overloading is probably all the more likely.) - Could there be another reason for this?
Why would there be any more overloading with an FPE Panel than say with a GE?


On occasion I find some discoloration. Okay, then I know the wires have been getting too hot, but sometimes I do not see any discoloration or, at least, it is less obvious. - Anyway, I am really just checking here to see if I am missing anything. Thanks in advance... :jester:

Heating, such as in the attic or with a circuit that has been overloaded may be an issue in many cases but I would bet there some of this is due to age. But that is just a SWAG.

If you look at the full load of the average house ignoring dryer, electric range, electric heat, electric water heater, ETC.....Branch circuit wiring sees relative low current draw.
 

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I thought the old NM was rubber insulation and rubber was just stickier.
 

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macmikeman said:
You hit it on the head. And lots of times the problem stripping the insulation is worse in attic junction boxes where the ambient heat is high and adds to the heat load on the wire. Another example is older fluorescent fixtures when the ballasts go bad, stripping insulation sometimes from the wires to the tombstones is harder than well, you know what from the ballast getting way too hot.
Those ballast wire can be a severe pain. After 10 or so, my fingers are hurting.
 

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Watt Pusher
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Regardless of what causes it, after trying to strip with strippers and finding it too hard, just squeeze the insulation with your lineman's pliers. It will ovalize and separate from the copper and you can pull it right off.
 

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Over time, the plasticizers used in the PVC conductor insulation leach out or dry up, leaving the remaining insulation brittle. That usually takes place after around 25+ years, but can happen sooner in attics or warm fixtures.

Yes, "ovalizing" it will make it easier to remove at that termination, but be aware that bending older wire that is like that also opens up micro fractures in the other areas of the insulation, exposing it to more moisture infiltration. If it's always dry, you may never have an issue, but if not, it might mean a call back, which to solve means replacing the conductors. I always used to warn people of that possibility. Occasionally that fear would lead to a rewire!:thumbsup:
 

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Discussion Starter · #12 ·
Why would there be any more overloading with an FPE Panel than say with a GE?





Heating, such as in the attic or with a circuit that has been overloaded may be an issue in many cases but I would bet there some of this is due to age. But that is just a SWAG.

If you look at the full load of the average house ignoring dryer, electric range, electric heat, electric water heater, ETC.....Branch circuit wiring sees relative low current draw.
As I understand it, FPE panels are known for not properly protecting circuit wiring because they do not always trip when they should. - Even while I was working on the home, I accidentally touched a ground to a hot wire and found that which normally causes most other circuit breakers to trip did nothing.
 

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Discussion Starter · #13 ·
Over time, the plasticizers used in the PVC conductor insulation leach out or dry up, leaving the remaining insulation brittle. That usually takes place after around 25+ years, but can happen sooner in attics or warm fixtures.

Yes, "ovalizing" it will make it easier to remove at that termination, but be aware that bending older wire that is like that also opens up micro fractures in the other areas of the insulation, exposing it to more moisture infiltration. If it's always dry, you may never have an issue, but if not, it might mean a call back, which to solve means replacing the conductors. I always used to warn people of that possibility. Occasionally that fear would lead to a rewire!:thumbsup:
Double thanks!!
 

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Lol...:laughing:
That sort of gives credit to Telsa that he doesn't deserve. That header has been there on my picture since the dawn of time, and my sense of humor is how it came about, since I came up with it. However I have Dennis Alwon to thank for supplying me the perfect avatar. Mahalo Dennis.
 

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I don't believe that overheating is the cause. I think that the chemical compound of some insulation is just different and it bonds to the wire more.

I've noticed it on SE cable, maybe more than NM.
 

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I don't believe that overheating is the cause. I think that the chemical compound of some insulation is just different and it bonds to the wire more.

I've noticed it on SE cable, maybe more than NM.
Different wire mfrs use different plasticizers in their insulation, and for sure, wire that has to be rated for UV exposure is chemically different from indoor wire, so yes, your observation makes sense.

Also, the plasticizers, compounds that make the PVC soft instead of brittle like pipe, have now changed for a lot of mfrs, because of newer rules coming up that will restrict the use of pthalate, a very common one that has now been linked to cancer and birth defects. So this situation is likely to get worse as time goes on.
 

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Regardless of what causes it, after trying to strip with strippers and finding it too hard, just squeeze the insulation with your lineman's pliers. It will ovalize and separate from the copper and you can pull it right off.
Thats the trick with asbestos i sulated wire too. A pinch this way, a pinch that way, give her a twist and off she comes.
 
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