Just moving into a new US location. The location has both Verizon and Comcast available. I am trying to use Comcast. The Verizon installer appears to have cut the Comcast cable that went to an interior wall cable plate, and then ran the other end into the FIOS ONT box's coaxial connection. The Comcast "Live" end is still hanging in the closet. Ideally I would like to put an male compression coaxial end onto that live cable and then use a cable extension adapter to join the cable back into one cable. This move allowing the flexibility to choose between FIOS or Xfinity as desired.

Is it safe to cut and crimp and put a compression end onto the cable that is going to Comcast's network or would re-cutting the presumably live cable, cause issues with Comcast's network equipment. This seems like an easy job, just not sure about the wiring, most of the cables I have crimped were not actually connected to anything while being made. Is this a case where I should just contact Comcast so they can disconnect and re-wire as needed?

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    Just a note. If you decide to switch back to Comcast, the installer will likely install new cables not use the old ones. If you're thinking you'll get free cable by reconnecting the cable, you'll be out of luck there too. If you have both services, the installer should not have cut the competitors cable.
    – Tester101
    Commented Feb 26, 2013 at 16:48
  • I don't have both services, the prior resident probably had an all FIOS play, additionally the providers have to share one line into the residence, since the owner will not allow additional outlets to be installed in to the walls,etc, hence the cord cutting, I hope to end that with the joiner. So that I or anyone after me can use whichever provider, just not at the same time.
    – MrDaniel
    Commented Feb 26, 2013 at 16:57
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    It's not likely the cable installers will stick to your plan. Installers hate your wires, and will not want to use your "inferior" cables and connectors.
    – Tester101
    Commented Feb 26, 2013 at 17:00
  • The wires that are there are Comcasts original wires, and in fact Verizon even used them, rather than installing their own new wire from the wall jack to the ONT.
    – MrDaniel
    Commented Feb 26, 2013 at 17:03
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    Installers generally use their own cables and connectors to insure quality of service. They have no idea if those old cables are good or not, so they'd prefer to make their own. Then if the customer calls about a problem, they know it's a problem with something they did, and not the previous guys issue.
    – Tester101
    Commented Feb 26, 2013 at 17:15

1 Answer 1


Cable installers work with "live" wires all the time. There's no voltage on their lines that I'm aware of, only signal and maybe some interference. You do need to disconnect lines for satellite dishes or mast mounted amplifiers since they may have a power injector that adds voltage into the lines.

When crimping the new cable, make sure the center wire is long enough (you can trim it after you crimp a new end) and get some of metal mesh that forms the second wire in tight contact with the crimped fastener. I usually pull some of that mesh back over the insulation so there's a tight bond when it's crimped.

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    The only time you wouldn't want to do this is if you're dealing with Satellite or mast mounted amplifiers that take their power off the coax. In those cases make sure the power injector is powered down or the cable is removed from the Satellite box. Standard cable TV shouldn't have any DC voltage on the cables to worry about. Commented Feb 26, 2013 at 16:43
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    @FiascoLabs FYI There can be over 50 volts on a coax line from a dish. Commented Feb 26, 2013 at 16:57
  • Thanks for the tip @FiascoLabs, I've edited my answer with those details.
    – BMitch
    Commented Feb 26, 2013 at 17:01
  • @maple_shaft Is the dish end supplying the power? As in the older C band LNB type stuff? Commented Feb 26, 2013 at 17:13
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    The signal is voltage. Commented Feb 27, 2013 at 16:47

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