[rferoni]

Hey all,

Helping a friend. Multiple modems, plugged into multiple outlets in his house, all putting out around 47 volts from the coax 'in' connector of modem. Nothing is connected to the modem. Modem is plugged into wall for power and a short peice of coax was connected to 'in' connector on modem for troubleshooting purposes. Just want to say again that he has tried multiple modems plugged into multiple outlets in his home all with same result.

The reason this all started was that he said his internet has been slow for quite awhile and he finally called out a tech. Tech said home electrical issue.

Outlets are wired correctly using a tester according to him.

Anyone have any ideas?

Thanks,
Ron

 

[chandler48]

At what two points are you measuring your voltage? Are you using a digital multimeter or analog. The latter will give more accurate readings, considering you are dealing with phantom voltage.

 

[diyorpay]

Any PoC (like PoE) devices anywhere?

 

[rferoni]

Just going by what friend said. Tech used digital multimeter measured from center pin on coax to GEC. Friend measured himself also using digital multimeter and said hes getting same voltage measured from outer portion of the f connector to GEC.



I've googled this issue and it seems like it could be a plethora of things...


Thanks again,
Ron

 

[rferoni]

Any PoC (like PoE) devices anywhere?

That shouldn't create and issue should it since the modem is simply plugged into an outlet with nothing else connected to it?


Thanks,
Ron

 

[seharper]

Sounds like a wall-wart power supply is leaking. I would unplug them until it goes away.

If it's not one of those, I'd look at any equipment plugged in to the ethernet. Unplug it from the ethernet and watch for it to go away.

 

[HotRodx10]

I had a similar issue, but more severe, that turned out to be a failing neutral on my incoming feed (my overhead power line from the street). My electrical was grounding through the cable. The cable guys were pretty freaked out that they were reading 120V on their coax.

 

[Datawise]

Two main causes for this in my experience.

1. Failed / failing neutral. The current will pass through the modem and use the braiding of the RG59 / RG6 to a common point. Usually will melt the jacketing of the coax fairly close to the modem.

2. Separate ground system used for the telecommunications / coax / data networks. Often you will see inexperienced people "grounding" their system separately from the electrical system. This causes a potential difference between the two systems and voltage (and sometimes current) can be measured on the individual systems.

There are other possibilities, but these are the two most common.

Cheers
John