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I was installing a new bath fan and had it all done. I was cleaning up the wires in the attic and accidentally put a staple through the wire as I was securing it to the lumber. I put some electrical tape around it and seems to be working.

There is not enough slack in the wire for me to cut it at the point where I pierced it. So my question is, do I need to have an electrician come out and replace or repair it, or is the electrical tape a safe solution?

Thank you.

  • you can use an ohmeter to see if any wire was cut: compare looped combo pairs. – dandavis Jun 19 '18 at 7:10
  • Would an ohm meter detect conductor damage? – isherwood Jun 19 '18 at 13:29
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If you damaged the conductor, tape doesn't help. The sharp edges and reduced cross-section result in concentrated resistance, which creates heat. In a max-current scenario it could burn and arc. That means sparks and potentially fire.

If you can determine that the conductors and their individual wire insulation weren't damaged, tape could be a viable (if not strictly legal) solution for repairing the outer jacket. Otherwise, replace the cable. You don't need an electrician to run a new cable between the fan and the switch box, for example.

  • Thanks, would cutting the cable and installing a junction box be an acceptable approach instead of running a new cable? – Carl Jun 18 '18 at 21:48
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    @Carl, you can splice the wire inside a junction box (may need two if not enough slack in the cable) but the junction box must remain accessible. i.e. can't hide it behind drywall. – Serguei Jun 18 '18 at 22:39
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    Thank you both. I ended up splicing it and installing a junction box in the attic. – Carl Jun 19 '18 at 0:57
  • @Carl, please accept an answer or provide and accept one of your own. Take the tour to understand how this network operates. – isherwood Jun 19 '18 at 13:28
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You could trim, back the outer jacket and check to see if the conductors are damaged. If the conductors are not damaged then you can reinsulate any skinned conductor insulation with good quality electrical tape. Then tape the cable in the damaged area to replace the outer jacket. Wire in an attic will not be exposed to any chaffing or wear so once it is taped up it will last for decades.

If any of the conductors are significantly damaged then you could use a splice such as this to repair the damaged area. They are Code legal and don't require extra slack in the cable. Splicing in a junction box will require butt splices not wire nuts. Wire nuts require slack to bring the conductors together parallel to each other.

Good luck!

  • Yeah -- just make sure you get a reputable, UL listed butt splice and a good quality (ratchet type) crimp tool with the correct die though, if you're going that route -- el-cheapo hardware store splices aren't going to be rated to UL486, most likely. – ThreePhaseEel Jun 19 '18 at 3:01
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The code legal approach is to cut the cable, insert both ends into a junction box, then complete the connection with small splice wire (wire nut, splice wire, wire nut). The junction box must be accessible after you're done, meaning a box with a blank cover.

Your electrical tape fix MIGHT be fine, or the conductors MIGHT be damaged. You could do a load test to determine, but for the simple DIY probably not.

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