So, I've been told that having insulation under your termination on a breaker, recep screw, etc. is a code violation. One my coworkers asked me to cite the code, which I could not. Is there any such code? I'm also curious abou t wrapping solid wire around screws, are there any codes pertaining to this?
wire terminations and insulation stripping
- Thread starter wankster
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
to your first question, the closest it is to a code violation would be that you did not follow the instructions supplied with the device that tells you how to properly terminate it.
as for wrapping solid wire around a a screw type terminal, again this is a matter of following the instructions. there is a rule in the code that says for listed devices you have to follow the instructions. it is odd that you are allowed to ignore the instructions for unlisted devices, but there is no similar requirement found in the code to follow the instructions that come with devices that are not listed.
PetrosA
Senior Member
- Location
- Lancaster, Pennsylvania
Generally, I'd say that 110.3 (B) and 110.14 (A) apply to both your questions.
JDBrown
Senior Member
- Location
- California
- Occupation
- Electrical Engineer
If you have access to an NEC Handbook, there's some very good commentary for section 110.14. I realize it's not part of the Code itself, but it looks nice and official and even has diagrams of the right and wrong ways to wrap wire around screws. It might be enough to convince your co-worker, especially if he doesn't realize that the commentary isn't enforceable. 
jwelectric
Senior Member
- Location
- North Carolina
Bob I know that you already know this but I want to point out that the instructions that are included in the listing and labeling not what comes packed with the equipment is what we are to follow when installing the equipment.
Listed or labeled equipment shall be installed and used in accordance with any instructions included in the listing or labeling.
Does the termination need to be UL listed? If so there must be a UL testing procedure in place. Then does such a procedure include an allowance to include the wire insulation to extend underneath the fastening device?
Simple common sense, if it should apply here, would conclude that electrical insulation is not a conductor of electricity. As such placing insulation under a fastener is not going to improve the connection. In addition the insulation adds thickness which the fastener would tighten down on first should would compromise the fastener's ability to apply sufficient pressure on the bare conductor to provide a good electrical connection.
Simple common sense, if it should apply here, would conclude that electrical insulation is not a conductor of electricity. As such placing insulation under a fastener is not going to improve the connection. In addition the insulation adds thickness which the fastener would tighten down on first should would compromise the fastener's ability to apply sufficient pressure on the bare conductor to provide a good electrical connection.
- Location
- Illinois
- Occupation
- retired electrician
UL is on record as saying any information supplied by the maufacturer with a listed product is a "listing and labeling instruction".
jwelectric
Senior Member
- Location
- North Carolina
UL may be on record as saying this but that doesn't mean that the instructions including with the packing of a piece of equipment is what is included in the instructions that are part of the listing and labeling.
Care for some examples?
Volta
Senior Member
- Location
- Columbus, Ohio
Sure. What'ch'ya got?
- Location
- Illinois
- Occupation
- retired electrician
Yes, not all of the information that you need is supplied with the product, and a lot you don't need, that UL says you must follow, is.
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