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MarkEM's avatar
New Contributor II

Voltage on Cable?

Not sure which forum this should be in but here goes...

I was moving some cabling and noticed a little spark when I disconnected the cable. I got out my voltmeter and measured 90 v AC across the cable coming in from the street. I was a bit surprised to find that. Is that normal? Why would it be there? I'm in the Phoenix area.

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  • EdwardH's avatar
    Valued Contributor
    For any market that still has analog phone you would get a active voltage up to the home that should be grounded at the box. Once it gets inside the home however you should not see more then millivolts to a given outlet. Do you get the same readings when testing a outlet in the home?

  • cpljp's avatar

    No you shouldn't. Voltage was provided through the coax drop to power old NIUs that were used for telephone service. Your main feed went into NIU and then there was an output on it where only RF passed and no power onto your other devices such as internet and cable boxes.

    You need to schedule a truck roll to remove the power limiter from inside the tap if you measured the AC from the center conductor on the coax. If you measured it on the coax shielding, then likely you have a bad neutral in your own house wiring causing the house's ground to be hot. 

  • MarkEM's avatar
    New Contributor II

    From some other research I suspect this is the case. We had Cox phone service many years ago so I suspect the shunt is still in place. A tech was out last week looking into low signal levels and one thing he did was to bypass the old phone box so there's probably nothing blocking the voltage now. I'll give them a call and see what happens.

    It is between the center conductor & shield, zero on the shield. we had a bad neutral several years ago so I know what that looks like.

    It does not appear to affect the the internet operation but I wonder what it's doing to my modem.

    Thanks for the response...

  • JonathanJ's avatar
    Former Moderator

    If you have problem schedule a technician out just email us with account information.