I live in Massachusetts and I'm having my unfinished attic turned into living space; I failed the initial rough inspection for a variety of reasons. One of the things the inspector told me is that the NM cable that runs into the nonmetallic boxes needs to be stripped back to no more than 1/8" extending into the box. I am certain he said this, and more than once.

This seemed really odd to me and when I had a licensed electrician come in and make all the fixes that needed to be made, he left at least an inch of sheathing in each box. When I questioned him on it and told him what the inspector said, he pointed to NEC 314.17-C, which states that there should be a minimum of 1/4" sheathing in the box, which makes a lot more sense to me.

The inspector is coming back today for a re-inspection and I'm wondering if this is going to be an issue. Has anyone ever heard this, or do you think I must have misheard him? Or was he referring to some other 1/8" requirement related to wiring up nonmetallic boxes and I misunderstood? I know he said it, so it's possible he just misspoke (and I'm hoping that's the case).

  • 6
    When the inspector comes back, ask for the code section he's referring to. Or better yet, call the building department, and ask for clarification.
    – Tester101
    Oct 18, 2016 at 13:28
  • Thanks, I'll do that. But I guess what I'm wondering is: does this sound strange to anyone else? Would it be normal for a town or inspector to have specific requirements that are so different from the NEC? Early on, I was told that the town uses the NEC plus Mass. addendums. I read those, and there is nothing about this issue in the Mass. document.
    – jevron1984
    Oct 18, 2016 at 15:07
  • 2
    Yes, inspectors are human, and so are prone to make mistakes. It's nearly impossible to memorize the code exactly as it's written, so misinformation can easily be spread. If you ask the inspector to show you the code, it allows them an opportunity to learn from their mistake (if they're willing to). Inspectors also tend to have pet peeves, which they tend to look for on every job. After working with the same inspector, you can learn these and avoid them.
    – Tester101
    Oct 18, 2016 at 15:18

1 Answer 1


In my state the inspector Shall cite the code to write a violation. Your electrician is correct there needs to be at least 1/4" of sheath left on the cable. This is to protect the wires from the sharp edges on the knock out type boxes and from the clamps on that style. My experience is inspectors don't like DIY home owners and pull all kinds of B.S. I recently moved to a diferent county and pulled some permits as a home owner, after the 3rd BS violation told him he needed to show me the code sections for each violation because the wiring was done by an electrician. He thought he was going to catch someone doing work on the side until I gave him my license number from memory let's just say he got very red in the face and after showing him my license he barely looked at the finish inspecton except for verifying the GFCI outlets functioned correctly.

  • That's a great story and, yes, I think that's what was going on here. He listed a number of other issues that multiple people I talked to agreed were B.S. Anyway, he came back for the re-inspection and didn't even look at the length of the sheathing in the boxes. So I passed. Thanks.
    – jevron1984
    Oct 28, 2016 at 12:36

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.