Basic Electrical Questions

I am doing some wiring and am wondering about a few basic things.
I notice that on a couple of wires after I had them pulled though the box and clamped down, the clear sheathing on the THNN wire, (romex as well as solid conductor) was roughed up or nicked or in a one case delaminating where the wire bends. I assume that this is OK. I assume that all I have to worry about is not damaging the insulation inself on the conductor? What is the purpose of this clear sheathing on the surface anyway?
Secondly, after I had some new boxes wired up, I measured the wire and found it to be about 7 1/2" from the front of the box. I know the recommendation is 8" but I have measured many boxes in the house and am hard pressed to find one with 8" of wire past the box. What is the normal length electricians usually leave past the front of the mudring?
Thirdly. I am running some Romex in the kitchen as whips under and over cabinets. In some locations the romex will be exposed before it enters surface mounted boxes. Is this a problem at all?
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Each layer of insulation has a purpose. I believe the clear layer on THHN aids in pulling of these conductors in conduit and adding to it's petroleum-resistant properties.

That's more than typical. You need enough wire to make your connections and/or splices, but you don't want too much or else it will be difficult to fold into the box afterwards. Some of those inches will be cut off when it's spliced.

As long as it's not subject to physical damage it's acceptable.
Add pictures here
<% if( /^image/.test(type) ){ %>
<% } %>
<%-name%>
Add image file
Upload

Site Timeline

HomeOwnersHub.com is a website for homeowners and building and maintenance pros. It is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.