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Old timer told me to stop using NM staples on MC cable, I didn't listen | Electricians - Free To Speak

Old timer told me to stop using NM staples on MC cable, I didn't listen

Had this old electrician named Joe on a job in Austin last summer. He kept telling me the NM staples I was using on MC cable would cause issues down the line. I thought he was just being old school and brushed him off. Fast forward 3 months, I came back to finish some trim out and found 4 staples had actually cut into the MC jacket at the corners. Had to re pull 60 feet of 12/2 MC because of it. Joe just shook his head when he saw me fixing it. Has anyone else run into weird code violations from using the wrong fasteners?

3 comments

3 Comments

jessej233mo ago

Bro Joe knew what was up for real. Those NM staples have those sharp little points that dig right into the soft MC jacket when the cable turns a corner. Seen it happen with 14/2 MC where the staple didn't even look tight but still gouged the jacket. Code actually says you gotta use staples listed for the cable type, not just what's in the van. Most guys dont know that 314.17 or whatever the number is specifically says the fastener cant damage the cable jacket. And the worst part is that damage shows up months later after the walls are closed, so you never even know you messed up until someone complains about a dead circuit.

blakestone3mo ago

Admit I used to just grab whatever staple was closest and thought it was fine. Always figured as long as it held the cable it was good enough. But seeing those sharp NM staples chew through MC jackets changed my mind hard. Now I check the box every time and make sure it's listed for the cable type. Saves a headache later for sure.

grant4783mo ago

That line about "damage shows up months later after the walls are closed" is exactly what happened to my buddy Mike. He did a whole house remodel, used NM staples on some 12/2 MC runs thinking it was all the same. Six months later the homeowner calls saying a bedroom circuit keeps tripping. Mike pulls the cover plate off a junction box and finds the MC jacket all chewed up where the staple was pinching it against a stud. Copper was exposed and arcing inside the wall. Cost him a full weekend to cut open drywall, replace the damaged section, and patch it all back up. He still brings it up anytime someone grabs the wrong staple, says it was the most expensive lesson he ever learned for saving two seconds picking the right box.