While building some shelves in my basement, I noticed an electrical cable than ran along a joist and dead-ended. I tested it and discovered it didn't have power. As the dead-end is not particularly far from the breaker box (~20 ft of cable), I'd like to remove it entirely just to be tidy.

I haven't yet removed the front panel of the break box to investigate because I wanted to do some reading first to make sure I feel comfortable doing so. I see plenty of articles and videos on how to replace circuit breakers (though I don't believe I want to replace or even remove any existing breakers).

However, what I do not see in those articles is what I should do to the breaker box after removing the cable. I assume I should replace the knock-out so that there isn't a hole in the side? Is there a recommended way to do so? Anything else I should do? Apologies that this is likely a very simple question - I'm just not sure on the terminology of what I should be searching for.

In the photo below, the cable I wish to remove is in the second black hole from the bottom (just above the yellow cable).

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You can plug the knockout hole with a knockout seal (or knockout plug).

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(source: homedepot.com)

You'll likely need either a 1/2" or 3/4", depending in the knockout size.

WARNING: When working in the panel, take your time, be careful, and manage loose wires and hands to keep them away from energized parts. Be especially cautious of the main lugs, and the ungrounded (hot) bus bars. Use insulated tools, and wear appropriate safety equipment.

  • 1
    +1 But if the cable is attached to a breaker in the box, it is potentially live. Be absolutely certain the cable's breaker is off before disconnecting the wire. Even better, turn off the main breaker (working with a flashlight) before putting a tool on the breakers.
    – bib
    Dec 4 '15 at 13:43
  • I disagree with turning off the main breaker. Working in the dark, is more hazardous than working in a live panel. In either case you still have to mind the main lugs. With the power off you might be a bit more complacent, and you're working in the dark.
    – Tester101
    Dec 4 '15 at 14:33
  • Can't really disagree. I just get nervous when a newbie approaches the main panel.
    – bib
    Dec 4 '15 at 14:39
  • As a newbie I find it much more safe to work with a few clip on flashlights and a headlamp knowing the entire box is safe. I have put in breakers and such inside a box, but I always turn off the main power before doing so. I don't do enough electricity work often enough to be comfortable otherwise. I have watched electricians fartz around inside boxes with power and I just don't have that skill.
    – ssaltman
    Dec 4 '15 at 15:14
  • 2
    @ssaltman The entire enclosure is not safe, unless there's a shutoff before the panel. The main lugs are always hot, and often quite exposed. Working in a way that you feel comfortable, is the key to safety. So I'm not going to tell anybody how to work, I just think working in the dark is not ideal.
    – Tester101
    Dec 4 '15 at 15:20

Best practice would be to shut down the main breaker while you do this.

Get yourself a good bright battery powered light to work by. Get all setup before you start. If anything doesn't go exactly as planned...STOP. Backup and take your time figuring your next move. Be patient and methodical. Avoid the area around the main breaker conductors. If any of the conductors are still terminated, carefully determinate them and cut the spare wire loose, at the connector, while you have a grip on it and remove it from the panel. Do not try to pull it backwards through the connector. Always maintain control of any loose conductor in the panel. After removing the connector, plug the knockout with a KO closer like Tester recommended. We usually bend a couple of the teeth out a little further so it stays in the knockout.

Do not work entirely alone. Make sure there is someone else on the premises monitoring your situation.

Wear safety glasses, a long sleeve shirt made of heavy denim (preferably flame rated), leather gloves (not nylon). Never wear any man made fabrics while working around energized equipment. They are essentially spun gasoline.

Be careful and good luck! 😊

  • The cable he is removing may be the only one going to a particular breaker. If that's the case, is it better to remove the unused breaker or just leave it in the box turned off?
    – JPhi1618
    Dec 4 '15 at 14:29
  • 1
    Unless he has a "blank-off" spacer for the internal breaker cover, to fill the hole left by the missing breaker, it's better to leave the unused breaker in the panel. In fact, it may be code required. My inspector wanted me to get blank-offs, it was easier to just stab breakers in there and mark them "unused". Dec 4 '15 at 17:27

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